Scenario 05: State investigates and responds to cyber operations against private actors in its territory

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The Bronze Soldier statue in Tallinn, Estonia. Photo by Keith Ruffles (CC-BY 3.0 Unported).

This scenario considers a series of malicious cyber operations originating from one State’s territory and targeting private entities on the territory of another. In the course of investigation, and after failing to receive cooperation from the suspected offending State, the victim State opts to penetrate the networks of the suspected offending State without consent. The victim State thereafter discovers that the suspected offending State’s military personnel was involved in some of the malicious cyber operations. This scenario analyses the rules of State responsibility, including attribution and the degrees of responsibility of the State of origin, the international obligations that may have been breached, and the ability of the victim State to justify its response under the law of countermeasures.

Scenario[edit | edit source]

Keywords[edit | edit source]

DDoS, computer data, attribution, State organs, non-State actors, evidence, sovereignty, prohibition of intervention, due diligence, countermeasures

Facts[edit | edit source]

[F1] Important commercial entities and financial institutions in State A fall victim to a massive distributed denial of service (DDoS) type of campaign for several days, resulting in down-time costs that amount to millions of EUR (incident 1).

[F2] Later, it is found that some of the computers were infected by malware and that the data, including operating system data, had been damaged or deleted, rendering the computers inoperative (incident 2). Most of the targeted entities have been able to recover the data from back-ups and restore the functionality of the computers, albeit at a substantial cost. No physical damage was caused in the incidents.

[F3] The incidents have been claimed by a group called “State B Digital Army” that has been active on the Internet for some time and is openly critical of foreign policy of State A. The group bears a name clearly referring to State B, which has in the past been allegedly involved in State-run cyber espionage operations against State A. State B has never admitted any relation to the group.

[F4] The technical aspects of the first incident, or rather its lack of sophistication, seem to suggest that the attackers were just an amateur group. By contrast, the scale of the second incident indicates that a State actor could have been involved in some capacity. Also, most of the group’s activities seem to originate from the territory of State B, although the persons involved and their exact location are unknown to State A.

[F5] Considering that States A and B have not had mutual diplomatic relations for many years, that State B is uncooperative in mutual legal assistance requests, and that there is a risk of destruction of evidence by State B, State A decides to remotely access several computers in the territory of State B without State B’s consent, in the course of a criminal investigation by State A’s cyber police unit in coordination with its intelligence service (incident 3).

[F6] During the cyber operation against State B, State A discovers that a minority of the malicious activities indeed originated from the network of the General Staff of the Armed Forces of State B (incident 4). State A is also able to identify some of the individuals responsible for the attacks and consequently issues public arrest warrants for these individuals, two of whom happen to be military personnel of State B serving in cyber intelligence (incident 5).

[F7] State B denies all allegations, stating that the military personnel were acting on their own, outside their working hours, and it decries the “violation of its sovereignty” by State A.

Examples[edit | edit source]

Legal analysis[edit | edit source]

For a general overview of the structure of analysis in this section, see Note on the structure of articles.

[L1] The legal analysis begins with the attribution of the incidents to States A and B, continues with possible breaches of international obligations by State B (sovereignty, prohibition of intervention, due diligence obligation) and State A (sovereignty), and ends with a possible justification for State A's response (countermeasures).

Attribution[edit | edit source]

State organs and exercise of governmental authority[edit | edit source]

State organs and persons and entities in exercise of governmental authority
The following types of conduct of State organs and persons and entities in exercise of governmental authority are attributable to a State:
  1. The conduct of any of the organs of that State, "whether the organ exercises legislative, executive, judicial or any other functions, whatever position it holds in the organization of the State, and whatever its character as an organ of the central Government or of a territorial unit of the State";[1]
  2. The conduct of "a person or entity which is not an organ of the State […] but which is empowered by the law of that State to exercise elements of the governmental authority, […] provided the person or entity is acting in that capacity in the particular instance";[2]
  3. The conduct of an organ of another State placed at the disposal of the State in question, if "the organ is acting in the exercise of elements of the governmental authority" of the latter State.[3]

Such conduct is attributable to the State even if the organ, person or entity acting in that capacity "exceeds its authority or contravenes instructions" (acts ultra vires).[4]

[L2] The fact that the operation against State A was partly launched from the governmental cyber infrastructure of State B, as found out in incident 4, is alone insufficient to attribute the operation to State B.[5] However, it indicates that State B may have been associated with the operation in question.[6] An argument for State B's involvement could be made if the network of its General Staff (as opposed to civilian governmental networks) is especially secure and unlikely to be controlled by a third Party and if the malicious activities were substantial and systematic.[7] Even so, there is insufficient information about a substantial or long-term involvement of State B in the activities.

[L3] Nevertheless, as soon as the two officers are identified in incident 5, the situation clearly changes, as they are State agents: even though State B claimed in the aftermath of the incidents that they had been acting on their own, their conduct would still be attributable to State B as the acts were performed by virtue of their official capacity.[8] This is because the mere fact that a State organ was acting ultra vires, i.e., in excess of authority or in contravention of instructions, does not remove attribution from the relevant State.[9] It is not necessary to prove that they were getting orders from their superiors, even though such information might be helpful for the purposes of criminal investigation conducted by State A authorities.

[L4] The information available to State A after incident 5 supports only an attribution of the conduct of the military personnel of State B to that State. By contrast, there does not seem to be sufficient evidence to link State B to any of the activities of the so-called “State B Digital Army” and its supporters. That being said, there are several options under the law of State responsibility on the basis of which such conduct might in fact be attributable to State B:

Non-State actors[edit | edit source]

Non-State actors
Activities of non-State actors (groups and individuals) are generally not attributable to States. However, such conduct can be attributable to a State in particular if the actor is:
  1. "in fact acting on the instructions of, or under the direction or control of, that State in carrying out the conduct";[10]

Each of the three criteria entails a form of subordination between the non-State actor and the potentially responsible State.[11] Regarding the criterion of control, there is a debate on the degree of control required for the attribution of the conduct to the State, as different tests have been developed.

On the one hand, the ICJ has affirmed that the exercise of “effective control” is necessary,[12] which entails that the State is able to control the beginning of the relevant operations, the way they are carried out, and their end.[13] This position has been expressly followed by some States in the realm of cyber operations, including Brazil,[14] the Netherlands[15] and Norway.[16]

On the other hand, a less restrictive approach has been developed by the ICTY,[17] and followed by the ICRC,[18] under the “overall control” test, which requires the State in question (i) to provide the non-State entity with financial and training assistance, military equipment and/or operational support, and (ii) to participate in the organization, co-ordination or planning of operations of the entity in question.[19] Nevertheless, the proponents of this test limit it to organized groups, meaning that the effective control test remains applicable for the conduct of private individuals, or unorganized groups.[20]

  1. "in fact exercising elements of the governmental authority in the absence or default of the official authorities and in circumstances such as to call for the exercise of those elements of authority";[21]
  2. "an insurrectional movement which becomes the new Government of a State";[22] or
  3. "a movement, insurrectional or other, which succeeds in establishing a new State in part of the territory of a pre-existing State or in a territory under its administration".[23]

Additionally,

  1. the conduct of a non-State actor is attributable to a State "if and to the extent that the State acknowledges and adopts the conduct in question as its own".[24]

[L5] Options 2–4 are manifestly inapplicable to the facts of the scenario given that there is no indication that the so-called State B Digital Army was exercising any form of governmental authority or attempting to form a State of its own. Option 5 (acknowledgment and adoption) also does not apply to the present facts because State B vehemently denied any association with the cyber operations against State A.

[L6] The only remaining mode of attribution is that under option 1, which reflects Article 8 of the ILC’s Articles on State Responsibility (i.e., the existence of instructions, direction, or control). The three standards of "instructions", "direction", or "control" can be satisfied by different conduct, but their common feature is the need to establish a form of subordination between the non-State actor and the potentially responsible State.[25]

  • The arguably most stringent factor of "instructions" would require "State B Digital Army" to be factually subordinated to State B, most commonly as an auxiliary, at the specific moment when the State decides to commit the acts in question. In this regard, the mere fact that State B and the "State B Digital Army" may have shared political goals and aims do not suffice for the purposes of attribution of the latter’s conduct to the former.[26]
  • The second standard would be met if an organ of State B "provided the direction pursuant to which the perpetrators of the wrongful act acted".[27] This would imply a continuing relationship of subordination between State B and "State B Digital Army", going beyond the mere issuance of instructions without follow-up.
  • Finally, the standard of "control" similarly refers to a continuing process of exercising authority by State B over an activity such as a cyber operation – to meet this standard, State B would have to go beyond merely supporting "State B Digital Army" and would have to go on to determine the execution and course of the specific cyber operation in question.

[L7] The mere fact that some of the activities were conducted from both governmental and private cyber infrastructure in State B is not sufficient.[28] What would need to be established is some form of subordination between the non-State actor and the potentially responsible State. As the scenario does not offer any indication of such subordination, it can be concluded that the available facts do not support the attributability of the conduct of "State B Digital Army" to State B.

Evidence[edit | edit source]

Evidentiary standards
Evidentiary standards applicable to the attribution of cyber activities are context-dependent.[29] The law of State responsibility as such does not contain generally applicable burdens, standards, or methods of proof,[30] and these matters are instead ordinarily determined by the relevant forum.[31]

It is generally understood that any allegation that a wrongful act has been committed by another State should be substantiated.[32] Nevertheless, there is no obligation under international law to publicly provide the evidence on which an attribution is based.[33] This has been reaffirmed by many States in their national positions, including Canada,[34] Finland,[35] France,[36] Germany,[37] Israel,[38] the Netherlands,[39] New Zealand,[40] Sweden,[41] Switzerland,[42] the United Kingdom[43] and the United States.[44] Some States have additionally affirmed that a “sufficient level of confidence”,[45] or “sufficient certainty”[46] must be reached before making a decision on attribution.

In case a State is considering a response to an internationally wrongful act, the standard of attribution is that of "reasonableness", i.e. "States must act as reasonable States would in the same or similar circumstances when considering responses to them."[47] This depends, among other factors, on the "reliability, quantum, directness, nature (e.g., technical data, human intelligence), and specificity of the relevant available information when considered in light of the attendant circumstances and the importance of the right involved."[48] The scope, scale, and impact of the incident have also been stressed as aspects that should be considered to support the assessment.[49] The utility of cooperation at the regional and international levels for attribution purposes has also been highlighted.[50]

Specific rules may apply to some responses, so when one State responds with countermeasures after misattributing an internationally wrongful act to another State, it commits an internationally wrongful act of its own, even though it correctly applied the "reasonableness" standard of attribution.[51]

[L8] In incidents 1 and 2, State A does not have much information to substantiate and ascertain who was responsible for the cyberattacks. Its decision to gather more evidence by launching a criminal investigation and accessing State B’s networks without asking for permission (incident 3) might be viewed as reasonable with regard to the circumstances (suspected involvement of State B), if there is no better way to obtain more evidence. This can qualify as a countermeasure of State A against State B (see the sections on extraterritorial jurisdiction and on countermeasures below). However, State A must be aware that it might be committing an internationally wrongful act if State B is not responsible for incidents 1-2, even if the hack-back seemed reasonable in the circumstances.

[L9] There is no legal obligation to publicly provide evidence upon which State A attributes the cyber operation to State B, even though States sometimes do this as a matter of good policy.[52]

Breach of an international obligation[edit | edit source]

Sovereignty of State A[edit | edit source]

Sovereignty
Sovereignty is a core principle of international law. According to a widely accepted definition of the term in the 1928 Island of Palmas arbitral award,
[s]overeignty in the relations between States signifies independence. Independence in regard to a portion of the globe is the right to exercise therein, to the exclusion of any other State, the functions of a State.[53]
Multiple declarations by the UN,[54] the African Union,[55] the European Union,[56] NATO,[57] OSCE,[58] and individual States have confirmed that international law applies in cyberspace. Accordingly, so too does the principle of sovereignty.[59] However, there is some debate as to whether this principle operates as a standalone rule of international law, the breach of which gives rise to state responsibility.
  • For the proponents of this view, the prohibition on violating the sovereignty of other States is a substantive primary rule of international law, the breach of which is an internationally wrongful act. This view was unanimously accepted by the experts who prepared the Tallinn Manual 2.0.[60] It has also been adopted by several States including Austria,[61] Brazil, [62] Canada,[63] the Czech Republic,[64] Estonia,[65] Finland,[66] France,[67] Germany,[68] Iran,[69] Italy,[70] Japan,[71] the Netherlands,[72] New Zealand,[73] Norway,[74] Romania[75] and Sweden.[76]
  • By contrast, the opposing view is that sovereignty is a principle of international law that may guide State interactions, but it does not amount to a standalone primary rule.[77] This view has been adopted by one State, the United Kingdom,[78] and has been partially endorsed by the U.S. Department of Defense General Counsel.[79] By this approach, cyber operations cannot violate sovereignty as a rule of international law, although they may constitute prohibited intervention, use of force, or other internationally wrongful acts.

The remainder of this section proceeds on the basis of the former “sovereignty-as-rule” approach. Those espousing the latter “sovereignty-as-principle” approach should refer to other relevant sections of the legal analysis (such as that on the prohibition of intervention or use of force).

It is understood that sovereignty has both an internal and an external component.[80] In the cyber context, the “internal” facet of sovereignty entails that “[a] State enjoys sovereign authority with regard to the cyber infrastructure, persons, and cyber activities located within its territory, subject to its international legal obligations.”[81][82] This encompasses both private and public infrastructure.[83] The external component entails that States are “free to conduct cyber activities in [their] international relations”, subject to their international law obligations.[84]

As a general rule, each State must respect the sovereignty of other States.[85]However, within the cyber realm – and particularly regarding remote cyber operations – there is still no agreement on the criteria[86] and the required threshold[87] to qualify an operation as a sovereignty violation.[88] It is clear that a cyber operation with severe destructive effects, comparable to a “non-cyber” armed attack or a use of force against a State, constitutes a violation of its sovereignty; however, with more subtle cyber operations, the question is far from settled.[89] Accordingly, the assessment needs to be done on a case-by-case basis.[90]

The following modalities, highlighted in the Tallinn Manual 2.0, represent different ways of determining what a “sovereignty violation” might mean in the context of cyber operations:

  1. A State organ conducting cyber operations against a target State or entities or persons located there while physically present in the target State's territory violates the target State's sovereignty.[91] This was agreed by all Experts drafting the Manual; however, “a few” of the Experts thought that the extensive State practice carved out an exception for espionage operations.[92]
  2. Causation of physical damage or injury by remote means;[93] again, “a few” Experts took the position that this is a relevant but not a determinative factor by itself.[94]
  3. Causation of a loss of functionality of cyber infrastructure: although the Tallinn Manual 2.0 experts agreed that a loss of functionality constituted “damage” and thus a breach of sovereignty, no consensus could be achieved as on the precise threshold for a loss of functionality (the necessity of reinstallation of the operating system or other software was proposed but not universally accepted);[95] Below this threshold, there was no agreement among the Experts whether operations that do not cause physical consequences or a loss of functionality qualify as a violation of sovereignty.[96]
  4. Interference with data or services that are necessary for the exercise of "inherently governmental functions";[97] although the Experts could not conclusively define the term "inherently governmental functions", they agreed that, for example, the conduct of elections would so qualify.[98]
  5. Usurpation of "inherently governmental functions", such as exercise of law enforcement functions in another State’s territory without justification.[99]

The Tallinn Manual’s view of what constitutes a violation of sovereignty has been expressly endorsed by several States including Canada,[100] Germany[101] and the Netherlands;[102] and followed to some extent by other States, such as the Czech Republic,[103] Norway,[104] Sweden[105] and Switzerland.[106] An alternative test has been proposed by France, which argues that a breach of sovereignty occurs already when there is “any unauthorised penetration by a State of [the victim State’s] systems”;[107]similarly, Iran has argued that “unlawful intrusion to the (public or private) cyber structures” abroad may qualify as a breach of sovereignty.[108]

Attributing the relevant cyber operation to a State different from the target State is a necessary prerequisite for qualifying the cyber operation as a violation of the target State's sovereignty.

Whether non-State actors can violate territorial sovereignty on their own is a matter of disagreement.[109]

Publicly available national positions that address this issue include: Common position of the African Union (2024) (2024), National position of Australia (2020) (2020), National position of Brazil (2021) (2021), National position of Canada (2022) (2022), National position of the People's Republic of China (2021) (2021), National position of Costa Rica (2023) (2023), National position of the Czech Republic (2020) (2020), National position of Denmark (2023) (2023), National position of Estonia (2019) (2019), National position of Estonia (2021) (2021), National position of Finland (2020) (2020), National position of France (2019) (2019), National position of Germany (2021) (2021), National position of Iran (2020) (2020), National position of Ireland (2023) (2023), National position of Israel (2020) (2020), National position of the Italian Republic (2021) (2021), National position of Japan (2021) (2021), National position of Kenya (2021) (2021), National position of the Netherlands (2019) (2019), National position of New Zealand (2020) (2020), National position of Norway (2021) (2021), National position of Pakistan (2023) (2023), National position of the Republic of Poland (2022) (2022), National position of Romania (2021) (2021), National position of Singapore (2021) (2021), National position of the Kingdom of Sweden (2022) (2022), National position of Switzerland (2021) (2021), National position of the United Kingdom (2018) (2018), National position of the United Kingdom (2021) (2021), National position of the United Kingdom (2022) (2022), National position of the United States of America (2012) (2012), National position of the United States of America (2016) (2016), National position of the United States of America (2020) (2020), National position of the United States of America (2021) (2021).

[L10] A violation of sovereignty on the basis of option 1 highlighted above is manifestly inapplicable as there is no indication that either incident 1 or 2 were perpetrated by entities physically present within the territory of State A.

[L11] Inherently governmental functions (options 4 and 5) were probably not affected by either incident 1 or 2 – the inability to pay invoices might have some effect on the functioning of some government organizations in State A, but the causation is probably not proximate enough given the short timeframe of the incident (several days). The organizations can postpone the payments due to unforeseeable and irresistible circumstances, which likely mitigates any adverse effects on their functions.

[L12] As for the remaining options 2 and 3, the DDoS attacks (incident 1) probably did not amount to a violation of State A’s sovereignty. There was no physical damage or injury, even though some individuals and entities in State A could be affected by being unable to pay for goods and services, and there were significant economic losses as a result of the attacks. The loss of functionality was only temporary[110] and did not require either the replacement of physical components or the reinstallation of the operating system.

[L13] However, the damage to and deletion of data (incident 2), leading to a loss of functionality requiring the reinstallation of operating systems, could qualify as a violation of State A’s sovereignty under option 3 above.[111] This is regardless of the fact that the affected infrastructure was non-governmental.[112]

Prohibited intervention by State B[edit | edit source]

Prohibition of intervention
The obligation of non-intervention, a norm of customary international law,[113] prohibits States from intervening coercively in the internal or external affairs of other States. Prohibited intervention was authoritatively defined by the International Court of Justice in the judgment on the merits in the 1986 Nicaragua v United States case:
A prohibited intervention must […] be one bearing on matters in which each State is permitted, by the principle of State sovereignty, to decide freely. One of these is the choice of a political, economic, social and cultural system, and the formulation of foreign policy. Intervention is wrongful when it uses methods of coercion in regard to such choices, which must remain free ones.[114]
In order for an act, including a cyber operation,[115] to qualify as a prohibited intervention, it must fulfil the following conditions:[116]
  1. The act must bear on those matters in which States may decide freely.[117] The spectrum of such issues is particularly broad and it includes both internal affairs (such as the “choice of a political, economic, social, and cultural system”[114] or the conduct of national elections[118]), and external affairs (“formulation of foreign policy”;[114] or “recognition of states and membership of international organisations”[119])—the so-called domaine réservé of States.[120] The content of the domaine réservé is determined by the scope and nature of the State's international legal obligations.
  2. The act must be coercive in nature. There is no generally accepted definition of “coercion” in international law. In this respect, two main approaches have emerged in the cyber context:[121]
    1. Under the first approach, an act is coercive if it is specifically designed to compel the victim State to change its behaviour with respect to a matter within its domaine reservé.[122] Under this approach, the “key is that the coercive act must have the potential for compelling the target State to engage in an action that it would otherwise not take (or refrain from taking an action it would otherwise take)”.[123]
    2. Under the second approach giving meaning to “coercion”, it is sufficient for an act to effectively deprive the target State of its ability to control or govern matters within its domaine reservé.[124] This latter approach distinguishes itself from the former by accepting that mere deprivation of the target State’s control over a protected matter, without actually or potentially compelling that State to change its behaviour, may constitute intervention.[125]
    Under both approaches, however, merely influencing the target State by persuasion or propaganda or causing a nuisance without any particular goal is insufficient to qualify as coercion.[126] The element of coercion also entails the requirement of intent.[127]

    While coercion is evident in the case of an intervention involving the use of force, ‘either in the direct form of military action, or in the indirect form of support for subversive or terrorist armed activities within another State’, as affirmed by the ICJ,[128] it is less clear with respect to non-forcible forms of interference.[129] Some States support the approach that intervention may take various forms, such as economic and political coercion.[130] One example that has been reiterated in several States’ positions, including Australia,[131] Brazil,[132] Canada,[133] Germany,[134] Israel,[135] New Zealand,[136] Norway,[137] Singapore,[138] the United Kingdom[139] and the United States,[140] is the case of cyber operations by a State interfering with another state’s ability to hold an election or manipulating the election results. Many States have affirmed that the assessment has to be done on a case-by-case basis.[141]

    Both potential and actual effects are considered to be relevant when assessing the coercion element.[142]

  3. Finally, there has to be a causal nexus between the coercive act and the effect on the internal or external affairs of the target State.[143]
  4. The prohibition of intervention applies between States, and thus it is not applicable to the activities of non-State groups, unless their conduct can be attributed to a State under the rules on attribution under international law.[144]

Publicly available national positions that address this issue include: Common position of the African Union (2024) (2024), National position of Australia (2020) (2020), National position of Brazil (2021) (2021), National position of Canada (2022) (2022), National position of Costa Rica (2023) (2023), National position of the People's Republic of China (2021) (2021), National position of Denmark (2023) (2023), National position of Estonia (2021) (2021), National position of France (2019) (2019), National position of Germany (2021) (2021), National position of Iran (2020) (2020), National position of Ireland (2023) (2023), National position of Israel (2020) (2020), National position of the Italian Republic (2021) (2021), National position of Japan (2021) (2021), National position of the Netherlands (2019) (2019), National position of New Zealand (2020) (2020), National position of Norway (2021) (2021), National position of Pakistan (2023) (2023), National position of the Republic of Poland (2022) (2022), National position of Romania (2021) (2021), National position of Singapore (2021) (2021), National position of the Kingdom of Sweden (2022) (2022), National position of Switzerland (2021) (2021), National position of the United Kingdom (2018) (2018), National position of the United Kingdom (2021) (2021), National position of the United Kingdom (2022) (2022), National position of the United States of America (2016) (2016), National position of the United States of America (2020) (2020), National position of the United States of America (2021) (2021).

[L14] It would be difficult to argue that State B was involved in a prohibited intervention in State A’s internal affairs. To begin with, it is uncertain whether State A’s domaine réservé — in itself a category of relative scope under international law — was affected by incidents 1-2. The cyber activities were targeting State A’s financial sector, which is traditionally perceived as private, even if State A had a share in its ownership. Perhaps if the operations had been directed at State A’s central bank or at the integrity of financial data upon which State A’s pension or welfare system relied, this would support the qualification of the operation as an intrusion into the domaine réservé.[145]

[L15] Even assuming that the first prong of the test was met by the cyber operations in question, there is no evidence that any of the incidents were coercive in nature as against State A. In other words, the available facts do not support any attempt to compel State A to take any action it would otherwise not take (required under the first approach to coercion described above), or to deprive it of its ability to control its affairs (required under the second approach). As such, the cyber operations in the scenario do not seem to qualify as a prohibited intervention under international law.

Due diligence obligation of State B[edit | edit source]

Due diligence
According to the traditional formulation by the ICJ in the Corfu Channel case, every State is under an “obligation not to allow knowingly its territory to be used for acts contrary to the rights of other States”.[146] In the cyber context, the UN General Assembly urged States already in 2000 to “ensure that their laws and practice eliminate safe havens for those who criminally misuse information technologies”.[147]

It is the matter of some controversy whether the principle of due diligence reflects a binding obligation applicable to cyber operations.[148] Some States have framed it within their national positions as one of the "voluntary, non-binding norms of responsible State behaviour"[149] in cyberspace, including Israel,[150] New Zealand,[151] the United Kingdom[152] and Canada.[153]

It has also been proposed that in the cyber context, it is preferable to construe due diligence as a standard of attribution rather than as a standalone primary rule of international law.[154] Nevertheless, the present analysis proceeds on the basis that as a matter of lex lata, due diligence constitutes a general international obligation for every State not to knowingly allow its territory to be used for internationally wrongful acts using cyber means.[155] This view has also been endorsed by a growing number of States, including Australia,[156] Czech Republic,[157] Estonia,[158] Finland,[159] France,[160] Germany,[161] Italy,[162] Japan,[163] the Netherlands,[164] Norway,[165] Switzerland,[166] and Sweden.[167]

Due diligence does not entail a duty of prevention,[168] but rather an obligation of conduct.[169] A State breaches its due diligence obligation in the presence of the following cumulative elements:

  1. The existence of acts (by a non-State actor or a third State[170]) contrary to the rights of a victim State,[171]
  2. which are conducted from or through the territory of the potentially responsible State (or from or through the territory or cyber infrastructure under its control),[172]
  3. which would have been unlawful if conducted by the potentially responsible State,[173]
  4. which have serious adverse consequences for the victim State,[174]
  5. with respect to which the potentially responsible State has actual or constructive knowledge,[175] and
  6. upon which the potentially responsible State can act, but fails to take all feasible measures.[176]

Publicly available national positions that address this issue include: Common position of the African Union (2024) (2024), National position of Australia (2020) (2020), National position of Canada (2022) (2022), National position of the People's Republic of China (2021) (2021), National position of Costa Rica (2023) (2023), National position of the Czech Republic (2020) (2020), National position of Denmark (2023) (2023), National position of Estonia (2019) (2019), National position of Estonia (2021) (2021), National position of France (2019) (2019), National position of Germany (2021) (2021), National position of Ireland (2023) (2023), National position of Israel (2020) (2020), National position of the Italian Republic (2021) (2021), National position of Japan (2021) (2021), National position of the Netherlands (2019) (2019), National position of New Zealand (2020) (2020), National position of Norway (2021) (2021), National position of the Republic of Poland (2022) (2022), National position of Romania (2021) (2021), National position of Singapore (2021) (2021), National position of the Kingdom of Sweden (2022) (2022), National position of Switzerland (2021) (2021), National position of the United Kingdom (2021) (2021), National position of the United States of America (2021) (2021).

[L16] The due diligence analysis is important in the situation when State A does not have enough evidence to attribute incidents 1-2 to State B directly. If State B is in breach of its obligation of due diligence, State A might still have the option of justifying its responsive operation (incident 3) as a countermeasure.

[L17] Following from the above analysis of sovereignty, incident 2 (the deletion of data leading to a loss of functionality) is contrary to the rights of State A, and would have been unlawful if conducted by State B. It would be more difficult to similarly qualify incident 1 (the DDoS attack).

[L18] The cyber activities leading to incident 2 were conducted from the cyber infrastructure in the territory of State B; however, State B’s due diligence obligation is not breached solely by the fact that these incidents happened, even though they may have resulted in serious adverse consequences and were contrary to the rights of State A. State A would have to prove that State B had an actual or constructive knowledge of the harmful cyber activities at the time they were launched, and that it neglected its duty to take all feasible measures to terminate them.

[L19] The information that some of the harmful cyber activities were launched from State B’s government infrastructure is available to State A from incident 4 onwards. Even if it cannot be proved that State B actually gave orders to its organs, or instructed or directed the non-State actors (“State B Digital Army”) to conduct the DDoS attacks and data deletion (see the section on attribution above), the constructive knowledge requirement (“should have known”) likely triggers the breach of its due diligence obligation for the activities originating from its government cyber infrastructure.[177] State B could argue that its government infrastructure was taken over by non-State actors or a third State, or that it did what was to be expected from a reasonable State to terminate the activities, but the burden of proof would then shift to its side.[178]

[L20] State B therefore violated its obligation of due diligence with respect to those harmful cyber activities in the scenario which made use of its governmental cyber infrastructure but could not be directly attributed to it. With respect to the conduct that is attributable to State B, that State bears direct responsibility, which supersedes any violation of due diligence.

Sovereignty of State B: extraterritorial jurisdiction by State A in State B[edit | edit source]

Sovereignty
Sovereignty is a core principle of international law. According to a widely accepted definition of the term in the 1928 Island of Palmas arbitral award,
[s]overeignty in the relations between States signifies independence. Independence in regard to a portion of the globe is the right to exercise therein, to the exclusion of any other State, the functions of a State.[179]
Multiple declarations by the UN,[180] the African Union,[181] the European Union,[182] NATO,[183] OSCE,[184] and individual States have confirmed that international law applies in cyberspace. Accordingly, so too does the principle of sovereignty.[185] However, there is some debate as to whether this principle operates as a standalone rule of international law, the breach of which gives rise to state responsibility.
  • For the proponents of this view, the prohibition on violating the sovereignty of other States is a substantive primary rule of international law, the breach of which is an internationally wrongful act. This view was unanimously accepted by the experts who prepared the Tallinn Manual 2.0.[186] It has also been adopted by several States including Austria,[187] Brazil, [188] Canada,[189] the Czech Republic,[190] Estonia,[191] Finland,[192] France,[193] Germany,[194] Iran,[195] Italy,[196] Japan,[197] the Netherlands,[198] New Zealand,[199] Norway,[200] Romania[201] and Sweden.[202]
  • By contrast, the opposing view is that sovereignty is a principle of international law that may guide State interactions, but it does not amount to a standalone primary rule.[203] This view has been adopted by one State, the United Kingdom,[204] and has been partially endorsed by the U.S. Department of Defense General Counsel.[205] By this approach, cyber operations cannot violate sovereignty as a rule of international law, although they may constitute prohibited intervention, use of force, or other internationally wrongful acts.

The remainder of this section proceeds on the basis of the former “sovereignty-as-rule” approach. Those espousing the latter “sovereignty-as-principle” approach should refer to other relevant sections of the legal analysis (such as that on the prohibition of intervention or use of force).

It is understood that sovereignty has both an internal and an external component.[206] In the cyber context, the “internal” facet of sovereignty entails that “[a] State enjoys sovereign authority with regard to the cyber infrastructure, persons, and cyber activities located within its territory, subject to its international legal obligations.”[81][207] This encompasses both private and public infrastructure.[208] The external component entails that States are “free to conduct cyber activities in [their] international relations”, subject to their international law obligations.[209]

As a general rule, each State must respect the sovereignty of other States.[210]However, within the cyber realm – and particularly regarding remote cyber operations – there is still no agreement on the criteria[211] and the required threshold[212] to qualify an operation as a sovereignty violation.[213] It is clear that a cyber operation with severe destructive effects, comparable to a “non-cyber” armed attack or a use of force against a State, constitutes a violation of its sovereignty; however, with more subtle cyber operations, the question is far from settled.[214] Accordingly, the assessment needs to be done on a case-by-case basis.[215]

The following modalities, highlighted in the Tallinn Manual 2.0, represent different ways of determining what a “sovereignty violation” might mean in the context of cyber operations:

  1. A State organ conducting cyber operations against a target State or entities or persons located there while physically present in the target State's territory violates the target State's sovereignty.[91] This was agreed by all Experts drafting the Manual; however, “a few” of the Experts thought that the extensive State practice carved out an exception for espionage operations.[92]
  2. Causation of physical damage or injury by remote means;[216] again, “a few” Experts took the position that this is a relevant but not a determinative factor by itself.[217]
  3. Causation of a loss of functionality of cyber infrastructure: although the Tallinn Manual 2.0 experts agreed that a loss of functionality constituted “damage” and thus a breach of sovereignty, no consensus could be achieved as on the precise threshold for a loss of functionality (the necessity of reinstallation of the operating system or other software was proposed but not universally accepted);[218] Below this threshold, there was no agreement among the Experts whether operations that do not cause physical consequences or a loss of functionality qualify as a violation of sovereignty.[219]
  4. Interference with data or services that are necessary for the exercise of "inherently governmental functions";[97] although the Experts could not conclusively define the term "inherently governmental functions", they agreed that, for example, the conduct of elections would so qualify.[98]
  5. Usurpation of "inherently governmental functions", such as exercise of law enforcement functions in another State’s territory without justification.[220]

The Tallinn Manual’s view of what constitutes a violation of sovereignty has been expressly endorsed by several States including Canada,[221] Germany[222] and the Netherlands;[223] and followed to some extent by other States, such as the Czech Republic,[224] Norway,[225] Sweden[226] and Switzerland.[227] An alternative test has been proposed by France, which argues that a breach of sovereignty occurs already when there is “any unauthorised penetration by a State of [the victim State’s] systems”;[228]similarly, Iran has argued that “unlawful intrusion to the (public or private) cyber structures” abroad may qualify as a breach of sovereignty.[229]

Attributing the relevant cyber operation to a State different from the target State is a necessary prerequisite for qualifying the cyber operation as a violation of the target State's sovereignty.

Whether non-State actors can violate territorial sovereignty on their own is a matter of disagreement.[230]

Publicly available national positions that address this issue include: Common position of the African Union (2024) (2024), National position of Australia (2020) (2020), National position of Brazil (2021) (2021), National position of Canada (2022) (2022), National position of the People's Republic of China (2021) (2021), National position of Costa Rica (2023) (2023), National position of the Czech Republic (2020) (2020), National position of Denmark (2023) (2023), National position of Estonia (2019) (2019), National position of Estonia (2021) (2021), National position of Finland (2020) (2020), National position of France (2019) (2019), National position of Germany (2021) (2021), National position of Iran (2020) (2020), National position of Ireland (2023) (2023), National position of Israel (2020) (2020), National position of the Italian Republic (2021) (2021), National position of Japan (2021) (2021), National position of Kenya (2021) (2021), National position of the Netherlands (2019) (2019), National position of New Zealand (2020) (2020), National position of Norway (2021) (2021), National position of Pakistan (2023) (2023), National position of the Republic of Poland (2022) (2022), National position of Romania (2021) (2021), National position of Singapore (2021) (2021), National position of the Kingdom of Sweden (2022) (2022), National position of Switzerland (2021) (2021), National position of the United Kingdom (2018) (2018), National position of the United Kingdom (2021) (2021), National position of the United Kingdom (2022) (2022), National position of the United States of America (2012) (2012), National position of the United States of America (2016) (2016), National position of the United States of America (2020) (2020), National position of the United States of America (2021) (2021).

[L21] There are two possible views as regards State A’s decision to remotely access several computers in State B’s territory in search of evidence (incident 3). On the first view, given that the resulting operation consisted merely of non-invasive collection of information, it did not as such interfere with State B’s governmental functions.[231] By contrast, the competing view is that because the operation was mounted in order to collect evidence for criminal proceedings without the consent of the territorial State, it therefore qualified as a non-consensual exercise of law enforcement functions in State A’s territory. As law enforcement is exclusively reserved to the territorial State under international law, on this view State B’s conduct would have violated State A’s sovereignty.[232]

[L22] In case State A’s conduct is considered to qualify as a breach of international law, it might, however, be able to justify its actions by invoking countermeasures, as detailed below.

Countermeasures by State A[edit | edit source]

Countermeasures
Countermeasures are “measures that would otherwise be contrary to the international obligations of an injured State vis-à-vis the responsible State, if they were not taken by the former in response to an internationally wrongful act by the latter in order to procure cessation and reparation”.[233] Several States, including Australia,[234] Austria,[235] Canada,[236] Estonia,[237] France,[238] Germany,[239] Italy,[240] Japan,[241] the Netherlands,[242] New Zealand,[243] Norway,[244] Singapore,[245] Sweden,[246] the United Kingdom,[247] and the United States,[248] have expressly confirmed the applicability of the law of countermeasures to cyber operations. Others, including Brazil,[249] China,[250] and Cuba,[251] have expressed caution in this regard. Countermeasures should be distinguished from retorsions, which are unfriendly but lawful acts by the aggrieved party against the wrongdoer.

As a matter of general international law, an injured State may only take countermeasures against the responsible State if the following conditions are met:

  1. The existence of a prior internationally wrongful act of the responsible State against the injured State.[252] If that act consists of a cyber operation, this means that the operation must have been amounted to a breach of the obligations of the responsible State that is attributable to that State;
  2. The injured State has called upon[253] the responsible State to fulfil its obligations arising from its internationally wrongful act;[254] and
  3. The injured State has notified the responsible State of its decision to take countermeasures, and offered to negotiate with that State, unless it is taking “urgent countermeasures as are necessary to preserve its rights.”[255] Some States, such as Canada,[256] Israel,[257] Norway,[258] the United Kingdom[259] and the United States[260] have advocated for a particular approach to the notification requirement in the cyber realm, in particular to preserve the effectiveness of the measures and/or to avoid exposing sensitive capabilities of the responding State.[261]

Additionally, the countermeasures must fulfil the following requirements:

  1. Their aim must be to induce the responsible State to comply with the legal consequences of its internationally wrongful act;[262] hence, the aim of countermeasures is restoration, not retribution or retaliation; and the countermeasures can only target the responsible State;
  2. They “shall, as far as possible, be taken in such a way as to permit the resumption of performance of the obligations in question”;[263]
  3. They shall not affect the obligation to refrain from the threat or use of force,[264] obligations for the protection of fundamental human rights, of a humanitarian character prohibiting reprisals, or other “obligations under peremptory norms of general international law”;[265] obligations under any dispute settlement procedure between the injured and responsible State, and obligations arising from the inviolability of diplomatic or consular agents, premises, archives and documents;[266] and
  4. They must be “commensurate with the injury suffered, taking into account the gravity” of the prior unlawful act and of the rights in question (i.e. the “proportionality” requirement).[267] However, proportionality does not require that the adopted measures must be equivalent, reciprocal or even in kind.[268] As clearly expressesd by many States, including Canada,[269] Germany,[270] Italy,[271] Japan,[272] Norway,[273] Sweden,[274] Switzerland,[275] the United Kingdom[276] and the United States,[277] countermeasures against cyber operations can be non-cyber in nature, and cyber countermeasures may be adopted in response to non-cyber wrongful acts.

Countermeasures are temporary in nature. In case the original internationally wrongful act has ceased, and the dispute is submitted in good faith to a court or tribunal with the authority to make decisions binding on the parties, countermeasures may not be taken and if already taken, must be suspended,[278] except if the responsible State fails to implement the dispute settlement procedures in good faith.[279] Countermeasures must also be terminated as soon as the responsible State has complied with its (secondary) obligations.[280]

There is an ongoing debate as to whether States that have not themselves been directly injured by an unlawful cyber operation may engage in countermeasures in support of the injured State (sometimes referred to as "collective countermeasures").[281] In particular, Estonia has opined that non-injured States “may apply countermeasures to support the state directly affected by the malicious cyber operation”,[282] a view that has also received some support from New Zealand.[283] This would apply where diplomatic action is insufficient, but no lawful recourse to use of force exists. This interpretation would allow States to offer active assistance to other States, which may not possess sufficient cyber capabilities themselves to counter an ongoing unlawful cyber operation, or otherwise deter the responsible State with other non-cyber countermeasures.[284] However, this view has since been rejected by at least one State (France),[285] while others, such as Canada, do not yet consider there to be “sufficient State practice or opinio juris to conclude that [collective countermeasures] are permitted under international law”.[286] Therefore, it has to be regarded as a call for progressive development of international law, rather than a statement of the current state of international law.

Whether a particular measure fulfils these conditions is an objective question,[287] while the burden of proof that the relevant conditions have been fulfilled falls on the injured State.[288] The exact standard of proof required is unsettled in international law and it will depend on the relevant forum. However, relevant international jurisprudence tends to rely on the standard of “clear and convincing evidence”.[289] This standard translates in practice into a duty to “convince the arbiter in question that it is substantially more likely than not that the factual claims that have been made are true”.[290] Importantly, if a State does resort to countermeasures on the basis of an unfounded assessment that a breach has occurred, it may incur in international responsibility for its own wrongful conduct.[291]

Publicly available national positions that address this issue include: National position of Australia (2020) (2020), National position of Brazil (2021) (2021), National position of Canada (2022) (2022), National position of Costa Rica (2023) (2023), National position of Denmark (2023) (2023), National position of Estonia (2019) (2019), National position of Estonia (2021) (2021), National position of Finland (2020) (2020), National position of France (2019) (2019), National position of Germany (2021) (2021), National position of Ireland (2023) (2023), National position of Israel (2020) (2020), National position of the Italian Republic (2021) (2021), National position of Japan (2021) (2021), National position of the Netherlands (2019) (2019), National position of New Zealand (2020) (2020), National position of Norway (2021) (2021), National position of the Republic of Poland (2022) (2022), National position of Romania (2021) (2021), National position of the Russian Federation (2021) (2021), National position of Singapore (2021) (2021), National position of the Kingdom of Sweden (2022) (2022), National position of Switzerland (2021) (2021), National position of the United Kingdom (2018) (2018), National position of the United Kingdom (2021) (2021), National position of the United Kingdom (2022) (2022), National position of the United States of America (2016) (2016), National position of the United States of America (2020) (2020), National position of the United States of America (2021) (2021).

[L23] An interesting question arises at this point: is State A engaging in countermeasures against State B by exercising its enforcement jurisdiction in State B’s territory? (Let us suppose that it would be a violation of State A’s obligation to respect State B’s sovereignty, unless it is State A’s lawful countermeasure.[292])

[L24] We know that State B’s activities in incident 2, which can be attributed to it based on the information obtained in incidents 4-5, may amount to a violation of State A’s sovereignty, and hence an internationally wrongful act by State B; accordingly, State A would be entitled to resort to countermeasures (supposing that the effects of State B’s activities were still ongoing – for instance, if some of the deleted data could not be restored). Also, let us suppose that State A did not have the obligation to call upon State B for cessation, non-repetition, and reparation, and that it did not have the obligation to notify State B of the impending countermeasure, because that would likely defeat its purpose.

[L25] The countermeasures are not engaging a peremptory norm, nor are they affecting an obligation which would be subject to a dispute settlement procedure. The envisaged countermeasure is likely commensurate with the injury suffered, considering the gravity of the wrongful act and the rights in question. As for the purpose of the countermeasure, it serves to induce State B to comply with its obligations, because it aims to establish a firm attribution of its internationally wrongful act.

[L26] However, State A does not have the information necessary for the attribution right after incidents 1 and 2. Is State A engaging in countermeasures, if State B’s internationally wrongful act has not been established?

[L27] Ex post facto, it seems that the countermeasures were lawful, because State B had committed an internationally wrongful act; ex ante, however, State A could not have known that. Intuitively, it may seem that State A paradoxically committed an internationally wrongful act in response to an internationally wrongful act of State B.

[L28] However, the standard for the taking of countermeasures is an objective one.[293] The law of State responsibility does not require a subjective element to establish the wrongfulness of an act, nor does it deal with factually impossible attempts of internationally wrongful acts.

[L29] According to the commentary to the Articles on State Responsibility, “[a] State which resorts to countermeasures based on its unilateral assessment of the situation does so at its own risk and may incur responsibility for its own wrongful conduct in the event of an incorrect assessment.”[293] Therefore, State A’s countermeasures were lawful: they were done in reaction to an objectively internationally wrongful act of State B.

Checklist[edit | edit source]

  • Attribution:
    • How much evidence exists tying the purported perpetrators of the incidents to State B?
    • What should be the evidentiary standard for making the attribution?
    • Does it matter that the operation against State A was partly launched from State B's governmental cyber infrastructure?
    • Does it matter that the operation against State A was partly conducted by public officials of State A?
    • Can the conduct of "State B Digital Army" be attributed to State B?
  • Sovereignty of State A:
    • When does a cyber operation against non-State actors violate the sovereignty of a State?
  • Prohibition of intervention:
    • Did State B's operation intrude into State A's domaine réservé?
    • Was State B's operation coercive?
  • Due diligence:
    • Did the relevant cyber operation adversely affect the rights of State A?
    • Was the cyber operation conducted from or through the territory of State B?
    • Would the cyber operation have been unlawful if conducted by State B?
    • Did the incident result in serious adverse consequences for State A?
    • Did State B know or should it have known of the incident in question?
    • Did State B take all feasible measures to put an end to the malicious cyber activities?
  • Sovereignty of State B:
    • Can State A exercise its jurisdiction in State B's cyber infrastructure when trying to ascertain the attribution to State B?
  • Countermeasures by State A:
    • Does State A commit an internationally wrongful act by responding to an act whose wrongfulness has not been ascertained?

Appendixes[edit | edit source]

See also[edit | edit source]

Notes and references[edit | edit source]

  1. ILC Articles on State Responsibility, Art 4(1).
  2. ILC Articles on State Responsibility, Art 5.
  3. ILC Articles on State Responsibility, Art 6.
  4. ILC Articles on State Responsibility, Art 7; Tallinn Manual 2.0, commentary to rule 15, paras. 6-7 and 12.
  5. Tallinn Manual 2.0, commentary to rule 15, para 13.
  6. Tallinn Manual 2.0, commentary to rule 15, para 13.
  7. Compare P Margulies, 'Sovereignty and Cyber Attacks: Technology's Challenge to the Law of State Responsibility' (2013) 14 MJIL, 16-17.
  8. ILC Articles on State Responsibility, commentary to Art 7, para 3.
  9. ILC Articles on State Responsibility, Art 7.
  10. ILC Articles on State Responsibility, Art 8; see also Kubo Mačák, ‘Decoding Article 8 of the International Law Commission’s Articles on State Responsibility: Attribution of Cyber Operations by Non-State Actors’ (2016) 21 JC&SL 405.
  11. Kubo Mačák, ‘Decoding Article 8 of the International Law Commission’s Articles on State Responsibility: Attribution of Cyber Operations by Non-State Actors’ (2016) 21 JCSL 405, 426–27.
  12. See: ICJ, Military and Paramilitary Activities in and against Nicaragua (Nicaragua v US) (Merits) [1986] ICJ Rep 14, para 115; ICJ, Case Concerning the Application of the Convention on the Prevention and Punishment of the Crime of Genocide (Bosnia and Herzegovina v Serbia and Montenegro) (Judgment) [2007] ICJ Rep 43, para 400.
  13. See Stefan Talmon, ‘The Responsibility of Outside Powers for Acts of Secessionist Entities’ (2009) 58(3) International and Comparative Law Quarterly 493, 503; Tomohiro Mikanagi and Kubo Mačák, ‘Attribution of cyber operations: an international law perspective on the Park Jin Hyok case’ (2020) 9(1) Cambridge International Law Journal 51, 63; See also Marco Roscini, Cyber Operations and the Use of Force in International Law (OUP 2014) 37-38.
  14. Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States, UNODA, A/76/136 (August 2021) 21.
  15. Government of the Kingdom of the Netherlands, Appendix: International law in cyberspace (26 September 2019) 6.
  16. Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States, UNODA, A/76/136 (August 2021) 71.
  17. Prosecutor v Tadić (Appeal Judgment) IT-94-1-A (ICTY, 15 July 1999) paras 116 and ff.
  18. ICRC (ed), Commentary to the First Geneva Gonvention (CUP 2016) para 409; ICRC (ed), Commentary to the Third Geneva Convention (CUP 2021) para 304
  19. Prosecutor v Prlić et al (Trial Judgment) IT-04-74-T (ICTY, 29 May 2013), para. 86(a); see also Kubo Mačák, ‘Decoding Article 8 of the International Law Commission’s Articles on State Responsibility: Attribution of Cyber Operations by Non-State Actors’ (2016) 21 JCSL 405, 422.
  20. Prosecutor v Tadić (Appeal Judgment) IT-94-1-A (ICTY, 15 July 1999) para 132; see also Antonio Cassese, ‘The Nicaragua and Tadić Tests Revisited in Light of the ICJ Judgment on Genocide in Bosnia’ (2007) 18(4) EJIL 649, 657.
  21. ILC Articles on State Responsibility, Art 9.
  22. ILC Articles on State Responsibility, Art 10(1).
  23. ILC Articles on State Responsibility, Art 10(2).
  24. ILC Articles on State Responsibility, Art 11.
  25. Kubo Mačák, ‘Decoding Article 8 of the International Law Commission’s Articles on State Responsibility: Attribution of Cyber Operations by Non-State Actors’ (2016) 21 JCSL 405, 426–27 (noting that all three standards under Article 8 share the need for “a subordinate relationship between the State and the private actor”) (emphasis removed).
  26. Kubo Mačák, ‘Decoding Article 8 of the International Law Commission’s Articles on State Responsibility: Attribution of Cyber Operations by Non-State Actors’ (2016) 21 JCSL 405, 415 (“the fact of a goal shared by the State and the private actor is insufficient without further evidence establishing the subordination between the two”).
  27. Case Concerning Application of the Convention on the Prevention and Punishment of the Crime of Genocide (Bosnia and Herzegovina v Serbia and Montenegro) (Judgement) [2007] ICJ Rep 43, para 406.
  28. Tallinn Manual 2.0, commentary to rule 15, para 13-14.
  29. See further Marco Roscini, ‘Evidentiary Issues in International Disputes Related to State Responsibility for Cyber Operations’ (2015) 50 Texas International Law Journal 233; Isabella Brunner, Marija Dobrić and Verena Pirker, ‘Proving a State’s Involvement in a Cyber-Attack: Evidentiary Standards Before the ICJ’ (2015) 25 Finnish Yearbook of International Law 75; Tomohiro Mikanagi and Kubo Mačák, ‘Attribution of Cyber Operations: An International Law Perspective on the Park Jin Hyok case’ (2020) 9 Cambridge International Law Journal 51, 64-68.
  30. ILC Articles on State Responsibility, commentary to chapter III, para 4 ("Questions of evidence and proof of such a breach fall entirely outside the scope of the articles."); ibid, commentary to Art 19, para 8 ("Just as the articles do not deal with questions of the jurisdiction of courts or tribunals, so they do not deal with issues of evidence or the burden of proof.").
  31. Tallinn Manual 2.0, Chapter 4 Section 1, para 8.
  32. UN Group of Governmental Experts on Developments in the Field of Information and Telecommunications in the Context of International Security, A/70/174 (22 July 2015) para. 28(f); UN Group of Governmental Experts on Advancing Responsible State Behaviour in Cyberspace in the Context of International Security, A/76/135 (14 July 2021) para 71.(g); Acknowledged by Brazil, Germany, Russia and Switzerland in their national positions.
  33. SeeTallinn Manual 2.0, Chapter 4 Section 1 chapeau, para 13.
  34. Government of Canada, International Law applicable in cyberspace (April 2022)
  35. International law and cyberspace - Finland's national position (2020)
  36. Ministry of Defense of France, International Law Applied to Operations in Cyberspace (9 September 2019) 11.
  37. Federal Government of Germany, ‘On the Application of International Law in Cyberspace’, Position Paper (March 2021) 12.
  38. Roy Schöndorf, Israel’s Perspective on Key Legal and Practical Issues Concerning the Application of International Law to Cyber Operations (8 December 2020)
  39. Government of the Kingdom of the Netherlands, Appendix: International law in cyberspace (26 September 2019) 6.
  40. The Application of International Law to State Activity in Cyberspace (1 December 2020) 3.
  41. Government Offices of Sweden, Position Paper on the Application of International Law in Cyberspace (July 2022) 5
  42. Federal Department of Foreign Affairs, ‘Switzerland's position paper on the application of international law in cyberspace’ (May 2021) 6.
  43. According to the UK Attorney General, "[t]here is no legal obligation requiring a state to publicly disclose the underlying information on which its decision to attribute hostile activity is based, or to publicly attribute hostile cyber activity that it has suffered in all circumstances." (UK Attorney General, Jeremy Wright QC MP, 'Cyber and International Law in the 21st Century' (23 May 2018); United Kingdom Foreign, Commonwealth & Development Office, Application of international law to states’ conduct in cyberspace: UK statement (3 June 2021)
  44. Brian J Egan, International Law and Stability in Cyberspace (10 November 2016) 19; Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States, UNODA, A/76/136 (August 2021) 141.
  45. See the national positions of Germany and Italy. See also New Zealand’s national position (“sufficient confidence”).
  46. See The Netherlands’ national position.
  47. Tallinn Manual 2.0, Chapter 4 Section 1, para 10; Cf. Yeager v Islamic Republic of Iran (1987) 17 Iran-US CTR 92, 101–02 (‘[I]n order to attribute an act to the State, it is necessary to identify with reasonable certainty the actors and their association with the State.’).
  48. Tallinn Manual 2.0, Chapter 4 Section 1, para 10.
  49. UN Group of Governmental Experts on Advancing Responsible State Behaviour in Cyberspace in the Context of International Security, A/76/135 (14 July 2021) para 24.
  50. UN Group of Governmental Experts on Advancing Responsible State Behaviour in Cyberspace in the Context of International Security, A/76/135 (14 July 2021) paras 24 and 27.
  51. Tallinn Manual 2.0, Chapter 4 Section 1, para 12; see also ILC Articles on State Responsibility, Art 49 para 3 (“A State taking countermeasures acts at its peril, if its view of the question of wrongfulness turns out not to be well founded.”)
  52. According to the UK Attorney General, "the UK can and does attribute malicious cyber activity where we believe it is in our best interests to do so, and in furtherance of our commitment to clarity and stability in cyberspace. Sometimes we do this publicly, and sometimes we do so only to the country concerned. We consider each case on its merits." (UK Attorney General, Jeremy Wright QC MP, 'Cyber and International Law in the 21st Century'.
  53. Island of Palmas (Neth. v. U.S.), 2 RIAA 829, 838 (Perm. Ct. Arb. 1928).
  54. UNGA Res 71/237 (30 December 2015) UN Doc A/RES/20/237.
  55. African Union Peace and Security Council, "Common African Position on the Application of International Law to the Use of Information and Communication Technologies in Cyberspace" (29 January 2024).
  56. Council of the European Union,"Council Conclusions on the Joint Communication to the European Parliament and the Council: Resilience, Deterrence and Defence: Building strong cybersecurity for the EU" (Council conclusions, 20 November 2017).
  57. North Atlantic Treaty Organization, 'Wales Summit Declaration' (issued by the Head of State and Government participating in the meeting of the North Atlantic Council in Wales (5 September 2015) para 72.
  58. Organization for Security and Cooperation in Europe, Decision No. 1202, OSCE Confidence-Building Measures to Reduce the Risks of Conflict Stemming from the Use of Information and Communication Technologies (Permanent Council, 10 March 2016) PC.DEC/1202.
  59. See UNGA, Report of the Group of Governmental Experts on Developments in the Field of Information andTelecommunications in the Context of International Security, UN Doc A/68/98 (24 June 2013) para 20; UNGA, Report of the Group of Governmental Experts on Developments in the Field of Information and Telecommunications in the Context of International Security, A/70/174 (22 July 2015) paras 27, 28(b); UNGA, Report of the Group of Governmental Experts on Advancing Responsible State Behaviour in Cyberspace in the Context of International Security, A/76/135 (14 July 2021) paras 70, 71(b).
  60. Michael N Schmitt, 'Virtual Disenfranchisement: Cyber Election Meddling in the Grey Zones of International Law' (2018) 19 ChiJIntlL 30,40; Tallinn Manual 2.0, rule 4 (‘A State must not conduct cyber operations that violate the sovereignty of another State’), and commentary to rule 4, para 2 (‘States shoulder an obligation to respect the sovereignty of other States as a matter of international law’).
  61. Austria, Pre-Draft Report of the OEWG - ICT: Comments by Austria (31 March 2020), stating that ‘a violation of the principle of State sovereignty constitutes an internationally wrongful act – if attributable to a State – for which a target State may seek reparation under the law of State responsibility’.
  62. Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States, UNODA, A/76/136 (August 2021) 18.
  63. Government of Canada, International Law applicable in cyberspace (April 2022) para 13.
  64. Czech Republic, Statement by Mr. Richard Kadlčák, Special Envoy for Cyberspace, 2nd substantive session of the Open-ended Working Group on developments in the field of information and telecommunications in the context of international security (11 February 2020), stating that ‘[t]he Czech Republic concurs with those considering the principle of sovereignty as an independent right and the respect to sovereignty as an independent obligation.’
  65. Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States, UNODA, A/76/136 (August 2021) 25.
  66. Finland, ‘International law and cyberspace: Finland’s national positions’ (15 October 2020), 3, stating that ‘Finland sees sovereignty as a primary rule of international law, a breach of which amounts to an internationally wrongful act and triggers State responsibility. This rule is fully applicable in cyberspace.’
  67. French Ministry of the Armies, ‘International Law Applied to Operations in Cyberspace’, 9 September 2019, stating that ‘Any unauthorised penetration by a State of French systems or any production of effects on French territory via a digital vector may constitute, at the least, a breach of sovereignty’.
  68. Germany, ‘On the Application of International Law in Cyberspace: Position Paper’ (March 2021), p. 3, noting that ‘Germany agrees with the view that cyber operations attributable to States which violate the sovereignty of another State are contrary to international law’.
  69. Iran, ‘Declaration of General Staff of the Armed Forces of the Islamic Republic of Iran Regarding International Law Applicable to the Cyberspace’ (July 2020), para 4 (‘Any utilization of cyberspace if and when involves unlawful intrusion to the (public or private) cyber structures which is under the control of another state, maybe constituted as the violation of the sovereignty of the targeted state.’).
  70. Italian Ministry for Foreign Affairs and International Cooperation, ‘Italian position paper on “International law and cyberspace”’ (2021) 4.
  71. Ministry of Foreign Affairs of Japan, ‘Basic Position of the Government of Japan on International Law Applicable to Cyber Operations’ (16 June 2021) 3.
  72. Dutch Ministry of Foreign Affairs, ‘Letter to the parliament on the international legal order in cyberspace’ (5 July 2019), stating that ‘countries may not conduct cyber operations that violate the sovereignty of another country’.
  73. New Zealand Foreign Affairs and Trade, ‘The Application of International Law to State Activity in Cyberspace’ (1 December 2020) 2.
  74. Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States, UNODA, A/76/136 (August 2021) 67.
  75. Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States, UNODA, A/76/136 (August 2021) 76.
  76. Government Offices of Sweden, ‘Position Paper on the Application of International Law in Cyberspace’ (July 2022) 2.
  77. Gary P. Corn and Robert Taylor, ‘Sovereignty in the Age of Cyber’ (2017) 111 AJIL Unbound 207, 208 (arguing that sovereignty is ‘a principle of international law that guides state interactions’).
  78. Jeremy Wright, ‘Cyber and International Law in the 21st Century’ (23 May 2018) (stating that he was ‘not persuaded that we can currently extrapolate from that general principle a specific rule or additional prohibition for cyber activity beyond that of a prohibited intervention. The UK Government’s position is therefore that there is no such rule as a matter of current international law’). The approach has been maintained in UK’s 2021 and 2022 national positions.
  79. Paul C. Ney, DOD General Counsel Remarks at U.S. Cyber Command Legal Conference, 2 March 2020, arguing that ‘the Department believes there is not sufficiently widespread and consistent State practice resulting from a sense of legal obligation to conclude that customary international law generally prohibits such non-consensual cyber operations in another State’s territory’.
  80. Cf. James Crawford, Brownlie's Principles of Public International Law (OUP 2012) 448.
  81. 81.0 81.1 Tallinn Manual 2.0, rule 2.
  82. Sovereignty over cyber infrastructure derives from the traditional concept of sovereignty, independent of the use of cyberspace. See Wolff Heintschel von Heinegg, 'Territorial Sovereignty and Neutrality in Cyberspace' (2013) 89 Int’l L. Stud. 123 (noting that '[t]erritorial sovereignty [..] implies that, subject to applicable customary or conventional rules of international law, the State alone is entitled to exercise jurisdiction, especially by subjecting objects and persons within its territory to domestic legislation and to enforce these rules'). This has been endorsed by several States, including China, the Czech Republic, Estonia, Finland, France, Germany, Israel, Italy, the Netherlands, Norway, Sweden, Switzerland and the United States.
  83. Tallinn Manual 2.0., commentary to rule 4, para 5. See also the national positions of Norway, Sweden and Switzerland.
  84. Tallinn Manual 2.0., rule 3; see also the national positions of the Czech Republic, the Netherlands and Norway.
  85. UN GA Res 2625 (XXV) (24 October 1970) (Friendly Relations Declaration), preamble (emphasizing “that the purposes of the United Nations can be implemented only if States enjoy sovereign equality and comply fully with the requirements of this principle in their international relations”); Tallinn Manual 2.0, rule 4.
  86. Some States have referred to the nature of the operation, its consequences, and/or the scale or severity of the effects, as the relevant factors that should be assessed. See e.g. the national positions of Canada, Finland, Germany, New Zealand, Norway, Sweden and Switzerland. New Zealand also highlighted the nature of the target in this regard.
  87. Some States have highlighted the requirement of certain level beyond “negligible” or “de minimis” effects, such as Canada and Germany. See similarly, New Zealand’s national position. For further discussion on the required threshold, see Michael N Schmitt and Liis Vihul, ‘Respect for Sovereignty in Cyberspace’ (2017) 95 Texas Law Review 1639; Harriet Moynihan, ‘The Application of International Law to State Cyberattacks. Sovereignty and Non-Intervention’, Chatham House (2 December 2019) paras 60 and ff.
  88. Michael Schmitt, ‘Sovereignty, Intervention, and Autonomous Cyber Capabilities’ (2020) 96 International Law Studies 549.
  89. Tallinn Manual 2.0, commentary to rule 4, para 5 and 12.
  90. See e.g. the national position of Canada, Finland, New Zealand, Norway, Sweden and Switzerland.
  91. 91.0 91.1 See, eg, Certain Activities Carried Out by Nicaragua in the Border Area (Costa Rica v Nicaragua) and Construction of a Road in Costa Rica along the San Juan River (Nicaragua v Costa Rica) (Judgment) [2015] ICJ Rep 665, 704–05, paras 97–99 (holding that the presence of Nicaragua’s military personnel in the territory under Costa Rica’s sovereignty amounted to a violation of Costa Rica’s territorial sovereignty); see also Tallinn Manual 2.0, commentary to rule 4, para 6.
  92. 92.0 92.1 Tallinn Manual 2.0, commentary to rule 4, para 7; commentary to rule 32, para 9. See also, the national positions of Canada and New Zealand.
  93. Tallinn Manual 2.0, commentary to rule 4, para 11.
  94. Tallinn Manual 2.0, commentary to rule 4, para 12.
  95. Tallinn Manual 2.0, commentary to rule 4, para 13. Additionally, there was agreement between the experts that ‘a cyber operation necessitating repair or replacement of physical components of cyber infrastructure amounts to a violation because such consequences are akin to physical damage or injury’. See also in this respect Canada’s national position.
  96. Tallinn Manual 2.0, commentary to rule 4, para 14.
  97. 97.0 97.1 Tallinn Manual 2.0, commentary to rule 4, para 15.
  98. 98.0 98.1 Tallinn Manual 2.0, commentary to rule 4, para 16. Other examples may include law enforcement, taxation, foreign relations and national defense. See e.g. the national positions of Canada, Germany and Norway. See also Michael Schmitt, ‘Sovereignty, Intervention, and Autonomous Cyber Capabilities’ (2020) 96 International Law Studies 549, 557.
  99. Tallinn Manual 2.0, commentary to rule 4, para 18.
  100. Government of Canada, International Law applicable in cyberspace (April 2022) para 13.
  101. Germany, ‘On the Application of International Law in Cyberspace: Position Paper’ (March 2021), p. 4.
  102. Dutch Ministry of Foreign Affairs, ‘Letter to the parliament on the international legal order in cyberspace’ (5 July 2019), p. 3.
  103. Richard Kadlčák, Statement of the Special Envoy for Cyberspace and Director of Cybersecurity Department of the Czech Republic (11 February 2020) 3.
  104. Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States, UNODA, A/76/136 (August 2021) 68.
  105. Government Offices of Sweden, Position Paper on the Application of International Law in Cyberspace (July 2022) 2
  106. Federal Department of Foreign Affairs, ‘Switzerland's position paper on the application of international law in cyberspace’ (May 2021) 3.
  107. Ministry of Defense of France, 'International Law Applied to Operations in Cyberspace' (9 September 2019) 6.
  108. Declaration of General Staff of the Armed Forces of the Islamic Republic of Iran Regarding International Law Applicable to the Cyberspace (August 2020) para 4 (‘Any utilization of cyberspace if and when involves unlawful intrusion to the (public or private) cyber structures which is under the control of another state, maybe constituted as the violation of the sovereignty of the targeted state’).
  109. In favour: see, e.g., Theodore Christakis, ‘The ICJ Advisory Opinion on Kosovo: Has International Law Something to Say about Secession?’ (2011) 24 LJIL 73, 84; Marcelo Kohen, ‘The Court’s Contribution to Determining the Content of Fundamental Principles of International Law’ in Giorgio Gaja and Jenny Grote Stoutenburg (eds), Enhancing the Rule of Law through the International Court of Justice (Brill 2012) 145. Against: see, eg, Tallinn Manual 2.0, commentary to rule 4, para 3; Romania’s national position (‘If there is not a State or State endorsed operation one can speak of a criminal act, which should be investigated and punished in accordance with the criminal law of the State concerned’).
  110. But see Tallinn Manual 2.0, commentary to rule 4, para. 14 (noting that some of the experts considered that “a temporary, but significant, loss of functionality, as in the case of a major DDoS operation” would qualify as a violation of the victim State’s sovereignty).
  111. Tallinn Manual 2.0, commentary to rule 4, para 13.
  112. Tallinn Manual 2.0, commentary to rule 2, para 3.
  113. The customary nature has been highlighted by several States, including Australia, Brazil, Germany, Iran, Norway, Sweden, the United Kingdom and the United States.
  114. 114.0 114.1 114.2 Military and Paramilitary Activities in and against Nicaragua (Nicaragua v US) (Merits) [1986] ICJ Rep 14 [205].
  115. Many States, including Australia, Brazil, Canada, Estonia, Israel, Italy, Japan, New Zealand, Norway, Singapore, Sweden, Switzerland, the United Kingdom and the United States, have acknowledged that the prohibition of intervention applies to cyber operations. This has been also highlighted by the UN Group of Governmental Experts. See UNGA, Report of the Group of Governmental Experts on Developments in the Field of Information and Telecommunications in the Context of International Security (22 July 2015) A/70/174, para 28(b); UNGA, Report of the Group of Governmental Experts on Advancing Responsible State Behaviour in Cyberspace in the Context of International Security (14 July 2021) A/76/135, para 71(c).
  116. Many States agree that intervention ‘involves “coercion” in relation to a State’s domaine réservé’. See Ori Pomson, 'The Prohibition on Intervention Under International Law and Cyber Operations' (2022) 99 International Law Studies 180, 217. In this regard, see the national positions of Australia, Brazil, Canada, Estonia, Germany, Israel, Italy, The Netherlands, New Zealand, Norway, Romania, Singapore, Sweden, Switzerland, the United Kingdom and the United States.
  117. Militarv and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America) Merits, Judgment. I.C.J. Reports 1986, 14 [241].
  118. Dutch Minister of Foreign Affairs, ‘Letter to the President of the House of Representatives on the International Legal Order in Cyberspace – Appendix: International Law in Cyberspace’ (5 July 2019), 3; Finland, ‘International law and cyberspace: Finland’s national positions’ (15 October 2020), 3; Germany, ‘On the Application of International Law in Cyberspace: Position Paper’ (March 2021), 5.
  119. Dutch Minister of Foreign Affairs, ‘Letter to the President of the House of Representatives on the International Legal Order in Cyberspace – Appendix: International Law in Cyberspace’ (5 July 2019), 3.
  120. See, for example, Katja Ziegler, “Domaine Réservé”, in Rudiger Wolfrum (ed), Max Planck Encyclopedia of Public International Law (OUP 2008) (updated April 2013) (defining the domaine réservé as those “areas where States are free from international obligations and regulation”); Nationality Decrees Issued in Tunis and Morocco (French Zone) on November 8th, 1921 (Great Britain v France) Advisory Opinion, (1923) PCIJ Series B no 4, 7th February 1923 [24].
  121. See also Harriet Moynihan, ‘The Vital Role of International Law in the Framework for Responsible State Behaviour in Cyberspace’ (2020) 6(3) Journal of Cyber Policy 394, 400-1.
  122. See, e.g., Dutch Minister of Foreign Affairs, ‘Letter to the President of the House of Representatives on the International Legal Order in Cyberspace – Appendix: International Law in Cyberspace’ (5 July 2019) 3, defining coercion as ‘compelling a state to take a course of action (whether an act or an omission) that it would not otherwise voluntarily pursue’ and noting that ‘[t]he goal of the intervention must be to effect change in the behaviour of the target state’; Germany, ‘On the Application of International Law in Cyberspace: Position Paper’ (March 2021), 5, defining coercion as a situation in which a State’s ‘will is manifestly bent by the foreign State’s conduct’ and noting that ‘the acting State must intend to intervene in the internal affairs of the target State’; see further, the national positions of Italy, Switzerland, Estonia, Norway and Romania; see also Tallinn Manual 2.0, commentary to rule 66, para 19 (‘The majority of Experts was of the view that the coercive effort must be designed to influence outcomes in, or conduct with respect to, a matter reserved to a target State.’).
  123. Tallinn Manual 2.0, commentary to rule 66, para 21. See also Dutch Minister of Foreign Affairs, ‘Letter to the President of the House of Representatives on the International Legal Order in Cyberspace – Appendix: International Law in Cyberspace’ (5 July 2019) 3.
  124. See, e.g., Australia, ‘Supplement to Australia’s Position on the Application of International Law to State Conduct in Cyberspace’ (2019) 4 (‘A prohibited intervention is one that interferes by coercive means (in the sense that they effectively deprive another state of the ability to control, decide upon or govern matters of an inherently sovereign nature), either directly or indirectly, in matters that a state is permitted by the principle of state sovereignty to decide freely.’); New Zealand, ‘The Application of International Law to State Activity in Cyberspace’ (1 December 2020), para 9(b) (stating that a State cyber activity is coercive if ‘there is an intention to deprive the target state of control over matters falling within the scope of its inherently sovereign functions’); United Kingdom Attorney General’s Office Suella Braverman: ‘International Law in Future Frontiers’ (19 May 2022). See also Tallinn Manual 2.0, commentary to rule 66, para 19 (‘A few Experts took the position that to be coercive it is enough that an act has the effect of depriving the State of control over the matter in question.’).
  125. Harriet Moynihan, ‘The Vital Role of International Law in the Framework for Responsible State Behaviour in Cyberspace’ (2020) 6(3) Journal of Cyber Policy 394, 403; see also Sean Watts, ‘Low-Intensity Cyber Operations and the Principle of Non-Intervention’ in Jens D Ohlin, Kevin Govern and Claire Finkelstein, Cyber War: Law and Ethics for Virtual Conflicts (Oxford University Press 2015) 256 and ff.
  126. Tallinn Manual 2.0, commentary to rule 66, para 21. See also the national positions of Canada, Germany and Norway.
  127. Tallinn Manual 2.0, commentary to rule 66, paras 19 and 27. See also the national positions of Germany, New Zealand and Sweden.
  128. Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America) Merits, Judgment. I.C.J. Reports 1986, 14 [205]. See also national position of Canada, Germany and The Netherlands.
  129. See Harriet Moynihan, The Application of International Law to State Cyberattacks Sovereignty and Non-Intervention (Chatham House, 2 December 2019) para 82.
  130. See Ori Pomson, 'The Prohibition on Intervention Under International Law and Cyber Operations' (2022) 99 International Law Studies 180, 212. While some States have stressed that economic coercion can still be sufficient for a breach of the rule of non-intervention, others remained ambiguous in their positions. States have referred to different examples that could be classified, depending on the circumstances of the case, under the prohibition of intervention. See the national positions of Australia (‘intervention in the fundamental operation of Parliament, or in the stability of States’ financial systems’), Canada (‘a malicious cyber activity that disrupts the functioning of a major gas pipeline, compelling the affected State to change its position in bilateral negotiations surrounding an international energy accord’), Italy (‘influence activities aimed, for instance, at undermining a State’s ability to safeguard public health during a pandemic’), New Zealand (‘a prolonged and coordinated cyber disinformation operation that significantly undermines a state’s public health efforts during a pandemic; and cyber activity deliberately causing significant damage to, or loss of functionality in, a state’s critical infrastructure, including – for example – its healthcare system, financial system, or its electricity or telecommunications network’), Norway (‘a cyber operation deliberately causing a temporary shutdown of the target State’s critical infrastructure, such as the power supply or TV, radio, Internet or other telecommunications infrastructure in order to compel that State to take a course of action’), Singapore (‘cyber-attacks against our infrastructure in an attempt to coerce our government to take or forbear a certain course of action on a matter ordinarily within its sovereign prerogative’), Switzerland (‘This is particularly true of economic coercion, which could be the case if a company that is systemically relevant was paralysed through a cyber operation’), the United Kingdom (‘intervention in the fundamental operation of Parliament, or in the stability of our financial system’; ‘to undermine the stability of another State’s financial system or to target the essential medical services of another State’; ‘Covert cyber operations by a foreign State which coercively restrict or prevent the provision of essential medical services or essential energy supplies […]disruption of systems controlling emergency medical transport (e.g., telephone dispatchers); causing hospital computer systems to cease functioning; disruption of supply chains for essential medicines and vaccines; preventing the supply of power to housing, healthcare, education, civil administration and banking facilities and infrastructure; causing the energy supply chain to stop functioning at national level through damage or prevention of access to pipelines, interchanges, and depots; or *preventing the operation of power generation infrastructure. Turning to economic stability, covert cyber operations by a foreign State that coercively interfere with a State’s freedom to manage its domestic economy, or to ensure provision of domestic financial services crucial to the State’s financial system, would breach the rule on non-intervention […] disruption to the networks controlling a State’s fundamental ability to conduct monetary policy or to raise and distribute revenue, for instance through taxation. Or disruption to systems which support lending, saving and insurance across the economy’), and the United States (‘a cyber operation that attempts to interfere coercively with a State’s ability to protect the health of its population –for example, through vaccine research or running cyber-controlled ventilators within its territories during a pandemic’).
  131. Australian Government, Australia's position on how international law applies to State conduct in cyberspace (2020).
  132. Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States, UNODA, A/76/136, (August 2021) 19.
  133. Government of Canada, International Law applicable in cyberspace (April 2022)
  134. Federal Government of Germany, ‘On the Application of International Law in Cyberspace’, Position Paper (March 2021) 5-6.
  135. Roy Schöndorf, Israel’s Perspective on Key Legal and Practical Issues Concerning the Application of International Law to Cyber Operations (8 December 2020).
  136. New Zealand Foreign Affairs and Trade, The Application of International Law to State Activity in Cyberspace (1 December 2020) 2.
  137. Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States, UNODA, A/76/136 (August 2021) 68-69.
  138. Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States, UNODA, A/76/136 (August 2021) 83.
  139. Attorney General Jeremy Wright:Cyber and International Law in the 21st Century (23 May 2018); United Kingdom Foreign, Commonwealth & Development Office, Application of international law to states’ conduct in cyberspace: UK statement (3 June 2021); Attorney General Suella Braverman: International Law in Future Frontiers, 19 May 2022.
  140. Brian J Egan, International Law and Stability in Cyberspace (10 November 2016) 13-14; Hon Paul C Ney, Jr., DOD General Counsel Remarks at U.S. Cyber Command Legal Conference (2 March, 2020); Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States, UNODA, A/76/136 (August 2021) 140.
  141. See the national positions of Canada, Romania, Sweden and Switzerland.
  142. Harriet Moynihan, The Application of International Law to State Cyberattacks Sovereignty and Non-Intervention (Chatham House, 2 December 2019) para 101. Further, the international group of experts involved in the Tallinn Manual 2.0. considered that ‘the fact that a coercive cyber operation fails to produce the desired outcome has no bearing on whether [the prohibition of intervention] has been breached’. Tallinn Manual 2.0., commentary to rule 66, para 29.
  143. Tallinn Manual 2.0, commentary to rule 66, para 24 (the exact nature of the causal nexus was not agreed on).
  144. Harriet Moynihan, The Application of International Law to State Cyberattacks Sovereignty and Non-Intervention (Chatham House, 2 December 2019) para 79. See also the national positions of The Netherlands (‘The non-intervention principle, like the sovereignty principle from which it stems, applies only between states’), Sweden (‘The prohibition of intervention is applicable between States and does not apply directly to non-state actors’), and the 2022 position of the United Kingdom (‘To be clear, State direction or control of non-State actors who undertake cyber operations of the kind I have described today would also represent unlawful conduct by that State, in line with international law on State responsibility’).
  145. Cf. Tim Maurer and Michael Schmitt, ‘Protecting Financial Data in Cyberspace: Precedent for Further Progress on Cyber Norms?Just Security, 14th August 2017 (“In the context of financial data, an operation targeting the integrity of financial data upon which the State pension or welfare system relied in order to compel the target State to adopt a particular domestic policy would exemplify prohibited cyber intervention.”). Additionally, some States have stated that cyber operations against the stability of a State’s financial systems might violate the principle of non-intervention. See the national positions of Australia, New Zealand, the United Kingdom and the United States.
  146. Corfu Channel Case (UK v Albania) (Merits) [1949] ICJ Rep 4, 22.
  147. UN GA Res 55/63 (4 December 2000), Doc A/RES/55/63, para 1(a).
  148. Cf. UN GGE 2015 report, paras 13(c) and 28(e) (using non-mandatory language to express the due diligence principle in the cyber context: “States should not knowingly allow their territory to be used for internationally wrongful acts using [cyber means]” and “States ... should seek to ensure that their territory is not used by non-State actors to commit such acts”, respectively) (emphases added); See also UN Group of Governmental Experts on Advancing Responsible State Behaviour in Cyberspace in the Context of International Security, A/76/135 (14 July 2021) paras 29-30.
  149. Dapo Akande, Antonio Coco and Talita de Souza Dias, ‘Old Habits Die Hard: Applying Existing International Law in Cyberspace and Beyond’, EJIL Talk! (5 January 2021)
  150. Roy Schöndorf, Israel’s Perspective on Key Legal and Practical Issues Concerning the Application of International Law to Cyber Operations (8 December 2020) 403-4. The position states that "we have not seen widespread State practice beyond this type of voluntary cooperation, and certainly not practice grounded in some overarching opinio juris, which would be indispensable for a customary rule of due diligence, or something similar to that, to form".
  151. New Zealand Foreign Affairs and Trade, ‘The Application of International Law to State Activity in Cyberspace’ (1 December 2020) 3. According to the position, "An agreed norm of responsible state behaviour provides that states should not knowingly allow their territory to be used for internationally wrongful acts using ICTs. Whether this norm also reflects a binding legal obligation is not settled".
  152. United Kingdom Foreign, Commonwealth & Development Office, ‘Application of international law to states’ conduct in cyberspace: UK statement’ (3 June 2021) para 12. According to the position: "the fact that States have referred to this as a non-binding norm indicates that there is not yet State practice sufficient to establish a specific customary international law rule of ‘due diligence’ applicable to activities in cyberspace".
  153. Government of Canada, International Law applicable in cyberspace (April 2022) para. 26. According to the position, this does not "precludes the recognition of a binding legal rule of due diligence under customary international law. Canada continues to study this matter".
  154. See Luke Chircop, ‘A Due Diligence Standard of Attribution in Cyberspace’ (2018) 67 ICLQ 643.
  155. See also Tallinn Manual 2.0, commentary to rule 6, para 4 (unanimously endorsing this view).
  156. Australia, ‘Australia’s International Cyber Engagement Strategy - Annex A: Australia’s Position on How International Law Applies to State Conduct in Cyberspace’ (October 2017) 91, stating that “if a state is aware of an internationally wrongful act originating from or routed through its territory, and it has the ability to put an end to the harmful activity, that state should take reasonable steps to do so consistent with international law”.
  157. Czech Republic, Comments submitted by the Czech Republic in reaction to the initial “pre-draft” report of the Open-Ended Working Group on developments in the field of information and telecommunications in the context of international security (undated), stating that “ICT-specific norms reflect a general principle of international law obliging States to ensure that territory and objects over which they enjoy sovereignty are not used to harm other States’ rights.”
  158. Estonia, ‘President of the Republic at the opening of CyCon 2019’ (29 May 2019), stating that “states have to make reasonable efforts to ensure that their territory is not used to adversely affect the rights of other states.”
  159. Finland, ‘Statement by Ambassador Janne Taalas at the second session of the open-ended Working Group (OEWG) on developments in the field of information and telecommunications in the context of international security’ (11 February 2020), stating that “States have an obligation not to knowingly allow their territory to be used for activities that cause serious harm to other States, whether using ICTs or otherwise.”
  160. French Ministry of the Armies, ‘International Law Applied to Operations in Cyberspace’ (9 September 2019) 6, stating that “In compliance with the due diligence requirement, [France] ensures that its territory is not used for internationally wrongful acts using ICTs. This is a customary obligation for States, which must (i) use cyberspace in compliance with international law, and in particular not use proxies to commit acts which, using ICTs, infringe the rights of other States, and (ii) ensure that their territory is not used for such purposes, including by non-state actors.”
  161. Federal Government of Germany, ‘On the Application of International Law in Cyberspace’, Position Paper (March 2021) 3.
  162. Italian Ministry for Foreign Affairs and International Cooperation, ‘Italian position paper on International law and cyberspace’ (2021) 6-7.
  163. Ministry of Foreign Affairs of Japan, ‘Basic Position of the Government of Japan on International Law Applicable to Cyber Operations’ (28 May 2021) 5.
  164. Dutch Ministry of Foreign Affairs, ‘Letter to the parliament on the international legal order in cyberspace’ (5 July 2019), stating that ‘The Netherlands ... does regard the principle [of due diligence] as an obligation in its own right, the violation of which may constitute an internationally wrongful act.’
  165. Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States’ UNODA, A/76/136 (August 2021) 71-2.
  166. Federal Department of Foreign Affairs, ‘Switzerland's position paper on the application of international law in cyberspace’ (May 2021) 7.
  167. Government Offices of Sweden, ‘Position Paper on the Application of International Law in Cyberspace’ (July 2022) 4.
  168. Tallinn Manual 2.0, commentary to rule 6, para 5.
  169. Cf. Case Concerning Application of the Convention on the Prevention and Punishment of the Crime of Genocide (Bosnia and Herzegovina v Serbia and Montenegro) (Judgement) [2007] ICJ Rep 43, para 430; see further James Crawford, State Responsibility: The General Part (CUP 2013) 226–32 (on the distinction between due diligence and obligations of prevention); Rudiger Wolfrum, ‘Obligation of Result Versus Obligation of Conduct: Some Thoughts About the Implementation of International Obligations’ in Mahnoush H Arsanjani et al, Looking to the Future: Essays on International Law in Honor of Michael Reisman (Brill 2010).
  170. While, in general, it is States, not individuals or private entities, which are able to violate international law, cyber operations carried out by individuals or private entities that nevertheless result in serious adverse consequences fall within a State’s due diligence obligation. See Tallinn Manual 2.0, commentary to rule 6, para 21.
  171. Corfu Channel judgment, para 22; Tallinn Manual 2.0, commentary to rule 6, para 2 and 15.
  172. Tallinn Manual 2.0, rule 6.
  173. Tallinn Manual 2.0, commentary to rule 6, para 18-24.
  174. Tallinn Manual 2.0, rule 6.
  175. Tallinn Manual 2.0, commentary to rule 6, para 37-42.
  176. Tallinn Manual 2.0, commentary to rule 6, para 43; commentary to rule 7, para 2 and 18.
  177. Tallinn Manual 2.0, commentary to rule 6, para 40.
  178. Cf. Joanna Kulesza, Due Diligence in International Law (Brill Nijhoff 2016) 53.
  179. Island of Palmas (Neth. v. U.S.), 2 RIAA 829, 838 (Perm. Ct. Arb. 1928).
  180. UNGA Res 71/237 (30 December 2015) UN Doc A/RES/20/237.
  181. African Union Peace and Security Council, "Common African Position on the Application of International Law to the Use of Information and Communication Technologies in Cyberspace" (29 January 2024).
  182. Council of the European Union,"Council Conclusions on the Joint Communication to the European Parliament and the Council: Resilience, Deterrence and Defence: Building strong cybersecurity for the EU" (Council conclusions, 20 November 2017).
  183. North Atlantic Treaty Organization, 'Wales Summit Declaration' (issued by the Head of State and Government participating in the meeting of the North Atlantic Council in Wales (5 September 2015) para 72.
  184. Organization for Security and Cooperation in Europe, Decision No. 1202, OSCE Confidence-Building Measures to Reduce the Risks of Conflict Stemming from the Use of Information and Communication Technologies (Permanent Council, 10 March 2016) PC.DEC/1202.
  185. See UNGA, Report of the Group of Governmental Experts on Developments in the Field of Information andTelecommunications in the Context of International Security, UN Doc A/68/98 (24 June 2013) para 20; UNGA, Report of the Group of Governmental Experts on Developments in the Field of Information and Telecommunications in the Context of International Security, A/70/174 (22 July 2015) paras 27, 28(b); UNGA, Report of the Group of Governmental Experts on Advancing Responsible State Behaviour in Cyberspace in the Context of International Security, A/76/135 (14 July 2021) paras 70, 71(b).
  186. Michael N Schmitt, 'Virtual Disenfranchisement: Cyber Election Meddling in the Grey Zones of International Law' (2018) 19 ChiJIntlL 30,40; Tallinn Manual 2.0, rule 4 (‘A State must not conduct cyber operations that violate the sovereignty of another State’), and commentary to rule 4, para 2 (‘States shoulder an obligation to respect the sovereignty of other States as a matter of international law’).
  187. Austria, Pre-Draft Report of the OEWG - ICT: Comments by Austria (31 March 2020), stating that ‘a violation of the principle of State sovereignty constitutes an internationally wrongful act – if attributable to a State – for which a target State may seek reparation under the law of State responsibility’.
  188. Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States, UNODA, A/76/136 (August 2021) 18.
  189. Government of Canada, International Law applicable in cyberspace (April 2022) para 13.
  190. Czech Republic, Statement by Mr. Richard Kadlčák, Special Envoy for Cyberspace, 2nd substantive session of the Open-ended Working Group on developments in the field of information and telecommunications in the context of international security (11 February 2020), stating that ‘[t]he Czech Republic concurs with those considering the principle of sovereignty as an independent right and the respect to sovereignty as an independent obligation.’
  191. Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States, UNODA, A/76/136 (August 2021) 25.
  192. Finland, ‘International law and cyberspace: Finland’s national positions’ (15 October 2020), 3, stating that ‘Finland sees sovereignty as a primary rule of international law, a breach of which amounts to an internationally wrongful act and triggers State responsibility. This rule is fully applicable in cyberspace.’
  193. French Ministry of the Armies, ‘International Law Applied to Operations in Cyberspace’, 9 September 2019, stating that ‘Any unauthorised penetration by a State of French systems or any production of effects on French territory via a digital vector may constitute, at the least, a breach of sovereignty’.
  194. Germany, ‘On the Application of International Law in Cyberspace: Position Paper’ (March 2021), p. 3, noting that ‘Germany agrees with the view that cyber operations attributable to States which violate the sovereignty of another State are contrary to international law’.
  195. Iran, ‘Declaration of General Staff of the Armed Forces of the Islamic Republic of Iran Regarding International Law Applicable to the Cyberspace’ (July 2020), para 4 (‘Any utilization of cyberspace if and when involves unlawful intrusion to the (public or private) cyber structures which is under the control of another state, maybe constituted as the violation of the sovereignty of the targeted state.’).
  196. Italian Ministry for Foreign Affairs and International Cooperation, ‘Italian position paper on “International law and cyberspace”’ (2021) 4.
  197. Ministry of Foreign Affairs of Japan, ‘Basic Position of the Government of Japan on International Law Applicable to Cyber Operations’ (16 June 2021) 3.
  198. Dutch Ministry of Foreign Affairs, ‘Letter to the parliament on the international legal order in cyberspace’ (5 July 2019), stating that ‘countries may not conduct cyber operations that violate the sovereignty of another country’.
  199. New Zealand Foreign Affairs and Trade, ‘The Application of International Law to State Activity in Cyberspace’ (1 December 2020) 2.
  200. Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States, UNODA, A/76/136 (August 2021) 67.
  201. Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States, UNODA, A/76/136 (August 2021) 76.
  202. Government Offices of Sweden, ‘Position Paper on the Application of International Law in Cyberspace’ (July 2022) 2.
  203. Gary P. Corn and Robert Taylor, ‘Sovereignty in the Age of Cyber’ (2017) 111 AJIL Unbound 207, 208 (arguing that sovereignty is ‘a principle of international law that guides state interactions’).
  204. Jeremy Wright, ‘Cyber and International Law in the 21st Century’ (23 May 2018) (stating that he was ‘not persuaded that we can currently extrapolate from that general principle a specific rule or additional prohibition for cyber activity beyond that of a prohibited intervention. The UK Government’s position is therefore that there is no such rule as a matter of current international law’). The approach has been maintained in UK’s 2021 and 2022 national positions.
  205. Paul C. Ney, DOD General Counsel Remarks at U.S. Cyber Command Legal Conference, 2 March 2020, arguing that ‘the Department believes there is not sufficiently widespread and consistent State practice resulting from a sense of legal obligation to conclude that customary international law generally prohibits such non-consensual cyber operations in another State’s territory’.
  206. Cf. James Crawford, Brownlie's Principles of Public International Law (OUP 2012) 448.
  207. Sovereignty over cyber infrastructure derives from the traditional concept of sovereignty, independent of the use of cyberspace. See Wolff Heintschel von Heinegg, 'Territorial Sovereignty and Neutrality in Cyberspace' (2013) 89 Int’l L. Stud. 123 (noting that '[t]erritorial sovereignty [..] implies that, subject to applicable customary or conventional rules of international law, the State alone is entitled to exercise jurisdiction, especially by subjecting objects and persons within its territory to domestic legislation and to enforce these rules'). This has been endorsed by several States, including China, the Czech Republic, Estonia, Finland, France, Germany, Israel, Italy, the Netherlands, Norway, Sweden, Switzerland and the United States.
  208. Tallinn Manual 2.0., commentary to rule 4, para 5. See also the national positions of Norway, Sweden and Switzerland.
  209. Tallinn Manual 2.0., rule 3; see also the national positions of the Czech Republic, the Netherlands and Norway.
  210. UN GA Res 2625 (XXV) (24 October 1970) (Friendly Relations Declaration), preamble (emphasizing “that the purposes of the United Nations can be implemented only if States enjoy sovereign equality and comply fully with the requirements of this principle in their international relations”); Tallinn Manual 2.0, rule 4.
  211. Some States have referred to the nature of the operation, its consequences, and/or the scale or severity of the effects, as the relevant factors that should be assessed. See e.g. the national positions of Canada, Finland, Germany, New Zealand, Norway, Sweden and Switzerland. New Zealand also highlighted the nature of the target in this regard.
  212. Some States have highlighted the requirement of certain level beyond “negligible” or “de minimis” effects, such as Canada and Germany. See similarly, New Zealand’s national position. For further discussion on the required threshold, see Michael N Schmitt and Liis Vihul, ‘Respect for Sovereignty in Cyberspace’ (2017) 95 Texas Law Review 1639; Harriet Moynihan, ‘The Application of International Law to State Cyberattacks. Sovereignty and Non-Intervention’, Chatham House (2 December 2019) paras 60 and ff.
  213. Michael Schmitt, ‘Sovereignty, Intervention, and Autonomous Cyber Capabilities’ (2020) 96 International Law Studies 549.
  214. Tallinn Manual 2.0, commentary to rule 4, para 5 and 12.
  215. See e.g. the national position of Canada, Finland, New Zealand, Norway, Sweden and Switzerland.
  216. Tallinn Manual 2.0, commentary to rule 4, para 11.
  217. Tallinn Manual 2.0, commentary to rule 4, para 12.
  218. Tallinn Manual 2.0, commentary to rule 4, para 13. Additionally, there was agreement between the experts that ‘a cyber operation necessitating repair or replacement of physical components of cyber infrastructure amounts to a violation because such consequences are akin to physical damage or injury’. See also in this respect Canada’s national position.
  219. Tallinn Manual 2.0, commentary to rule 4, para 14.
  220. Tallinn Manual 2.0, commentary to rule 4, para 18.
  221. Government of Canada, International Law applicable in cyberspace (April 2022) para 13.
  222. Germany, ‘On the Application of International Law in Cyberspace: Position Paper’ (March 2021), p. 4.
  223. Dutch Ministry of Foreign Affairs, ‘Letter to the parliament on the international legal order in cyberspace’ (5 July 2019), p. 3.
  224. Richard Kadlčák, Statement of the Special Envoy for Cyberspace and Director of Cybersecurity Department of the Czech Republic (11 February 2020) 3.
  225. Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States, UNODA, A/76/136 (August 2021) 68.
  226. Government Offices of Sweden, Position Paper on the Application of International Law in Cyberspace (July 2022) 2
  227. Federal Department of Foreign Affairs, ‘Switzerland's position paper on the application of international law in cyberspace’ (May 2021) 3.
  228. Ministry of Defense of France, 'International Law Applied to Operations in Cyberspace' (9 September 2019) 6.
  229. Declaration of General Staff of the Armed Forces of the Islamic Republic of Iran Regarding International Law Applicable to the Cyberspace (August 2020) para 4 (‘Any utilization of cyberspace if and when involves unlawful intrusion to the (public or private) cyber structures which is under the control of another state, maybe constituted as the violation of the sovereignty of the targeted state’).
  230. In favour: see, e.g., Theodore Christakis, ‘The ICJ Advisory Opinion on Kosovo: Has International Law Something to Say about Secession?’ (2011) 24 LJIL 73, 84; Marcelo Kohen, ‘The Court’s Contribution to Determining the Content of Fundamental Principles of International Law’ in Giorgio Gaja and Jenny Grote Stoutenburg (eds), Enhancing the Rule of Law through the International Court of Justice (Brill 2012) 145. Against: see, eg, Tallinn Manual 2.0, commentary to rule 4, para 3; Romania’s national position (‘If there is not a State or State endorsed operation one can speak of a criminal act, which should be investigated and punished in accordance with the criminal law of the State concerned’).
  231. See in general the discussion on the threshold for cyber operations to amount to a violation of another State’s sovereignty. For example, some States such as New Zealand stress that ‘sovereignty [does not prohibit] every unauthorised intrusion into a foreign ICT system or […] all cyber activity which has effects on the territory of another state’; whereas a minority position followed by France states that ‘any unauthorised penetration by a State of French systems or any production of effects on French territory via a digital vector may constitute, at the least, a breach of sovereignty’.
  232. Compare Tallinn Manual 2.0, commentary to rule 4, para 18: “if one State conducts a law enforcement operation against a botnet in order to obtain evidence for criminal prosecution by taking over its command and control servers located in another State without that State’s consent, the former has violated the latter’s sovereignty because the operation usurps an inherently governmental function exclusively reserved to the territorial State under international law.”
  233. ILC Articles on State Responsibility, Commentary, part 3 ch 2 at para 1.
  234. Australian Government, Australia's position on how international law applies to State conduct in cyberspace (2020).
  235. Austria, Pre-Draft Report of the OEWG - ICT: Comments by Austria (31 March 2020), stating that ‘a violation of the principle of State sovereignty constitutes an internationally wrongful act – if attributable to a State – for which a target State may seek reparation under the law of State responsibility. A target State may also react through proportionate countermeasures.’ (emphasis added).
  236. Government of Canada, International Law applicable in cyberspace (April 2022) para 34.
  237. Estonia, ‘President of the Republic at the opening of CyCon 2019’ (29 May 2019), stating that “states have the right to react to malicious cyber operations, including using diplomatic response but also countermeasures”
  238. French Ministry of the Armies, ‘International Law Applied to Operations in Cyberspace’ (9 September 2019) 6, stating that ‘In response to a cyberattack, France may consider diplomatic responses to certain incidents, countermeasures, or even coercive action by the armed forces if an attack constitutes armed aggression.’
  239. Germany, ‘Statement by Ambassador Dr Thomas Fitschen, Director for the United Nations, Cyber Foreign Policy and Counter-Terrorism, Federal Foreign Office of Germany’ (November 2018) 3, stating that ‘in case of a cyber operation that is in breach of an international legal obligation below the level of the use or threat of force prohibited by Art. 2 (IV) [of the UN Charter] States are also entitled to take countermeasures as allowed by international law.’
  240. Italian Ministry for Foreign Affairs and International Cooperation, 'Italian position paper on "International law and cyberspace"' (2021) 7-8.
  241. Japan, ‘Japan’s Position Paper for the Report of the United Nations Open-Ended Working Group on “Developments in the Field of Information and Telecommunications in the Context of International Security”’ (undated), stating that ‘Japan recognizes that basic rules on State responsibility including those on countermeasures applies to cyberspace.’
  242. Dutch Ministry of Foreign Affairs, ‘Letter to the parliament on the international legal order in cyberspace’ (5 July 2019) 7.
  243. New Zealand Foreign Affairs and Trade, The Application of International Law to State Activity in Cyberspace (1 December 2020) 3-4.
  244. Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States, UNODA, A/76/136 (August 2021) 72-73.
  245. Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States, UNODA, A/76/136 (August 2021) 84.
  246. Government Offices of Sweden, Position Paper on the Application of International Law in Cyberspace (July 2022) 6.
  247. United Kingdom, ‘Statement on Other Disarmament Measures and International Security to the 72nd UNGA First Committee’ (23 October 2017), stating that ‘We reaffirm that the law of state responsibility applies to cyber operations in peacetime, including the availability of the doctrine of countermeasures in response to internationally wrongful acts.’
  248. Brian J. Egan, ‘Remarks on International Law and Stability in Cyberspace’ (10 November 2016), stating that countermeasures are available ‘to address malicious cyber activity’ if that activity amounts to a prior internationally wrongful act attributable to another State.
  249. Brazil, ‘Open-ended Working Group on developments in the field of information and telecommunications in the context of international security: Second Substantive Session - New York, 11 February 2020: Statement by the Delegation of Brazil’ (11 February 2020), stating that ‘In the case of malicious acts in cyberspace, it is often difficult to attribute responsibility to a particular State or actor with unqualified certainty. A decision to resort to countermeasures in response to such acts carries a high risk of targeting innocent actors, and of triggering escalation.’
  250. China, ‘Statement by the Chinese Delegation at the Thematic Debate of the First Committee of the 72th UNGA’ (October 2017), stating that ‘Countries should discuss application of international law in the manner conducive to maintain peace, avoid introducing force, deterrence and countermeasures into cyberspace, so as to prevent arms race in cyberspace and reduce risks of confrontation and conflicts.’
  251. Cuba, ‘Declaration by Miguel Rodríguez, Representative of Cuba, at the Final Session of Group of Governmental Experts on Developments in the Field of Information and Telecommunications in the Context of International Security’ (23 June 2017), registering ‘serious concern over the pretension of some, reflected in para 34 of the draft final report, to convert cyberspace into a theater of military operations and to legitimize, in that context, unilateral punitive force actions, including the application of sanctions and even military action by States claiming to be victims of illicit uses of ICTs.’ (emphasis added).
  252. ILC Articles on State Responsibility, Art 49 para 1; Case Concerning the Gabčíkovo-Nagymaros Project (Hungary/Slovakia) (Judgment) 1997 ICJ Rep 7, para 83.
  253. ILC Articles on State Responsibility, Art 52 para 1 subpara a). According to the UK Attorney General, the UK does not feel legally obliged, when taking countermeasures in response to a covert cyber intrusion, to “give prior notification to the hostile state”. UK Attorney General, Jeremy Wright QC MP, ‘Cyber and International Law in the 21st Century’.
  254. ILC Articles on State Responsibility, Art 28-41; the list of consequences includes (i) continued duty of performance, (ii) cessation and non-repetition, (iii) reparation, and (iv) particular consequences of a serious breach of obligations under peremptory norms of general international law.
  255. ILC Articles on State Responsibility, Art 52 para 1 subpara b) – Art 52 para 2.
  256. Government of Canada, International Law applicable in cyberspace (April 2022).
  257. Roy Schöndorf, Israel’s Perspective on Key Legal and Practical Issues Concerning the Application of International Law to Cyber Operations (8 December 2020).
  258. Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States, UNODA, A/76/136 (August 2021) 72-73.
  259. UK Attorney General, Jeremy Wright QC MP, ‘Cyber and International Law in the 21st Century’ (2018); United Kingdom Foreign, Commonwealth & Development Office, Application of international law to states’ conduct in cyberspace: UK statement (3 June 2021).
  260. Hon Paul C Ney, Jr., DOD General Counsel Remarks at U.S. Cyber Command Legal Conference (2 March 2020).
  261. See also Tallinn Manual 2.0, commentary to rule 21, paras 10–12.
  262. ILC Articles on State Responsibility, Art 49(1); Case Concerning the Gabčíkovo-Nagymaros Project (Hungary/Slovakia) (Judgment) 1997 ICJ Rep 7, para 87. The list of consequences in Art 28-41 includes (i) continued duty of performance, (ii) cessation and non-repetition, (iii) reparation, and (iv) particular consequences of a serious breach of obligations under peremptory norms of general international law.
  263. ILC Articles on State Responsibility, Art 49(3).
  264. The position of the ILC has been followed by States in their national positions, including Australia, Brazil, Canada, Finland, France, Italy, the Netherlands, New Zealand, Norway, Russia, Sweden, Switzerland and the UK. For an alternative view on “forcible countermeasures” see Oil Platforms (Islamic Republic of Iran v. United States of America) Judgment, I.C.J. Reports 2003, 16, Separate Opinion of Judge Simma [12 and ff].
  265. ILC Articles on State Responsibility, Art 50(1).
  266. ILC Articles on State Responsibility, Art 50(2).
  267. Articles on State Responsibility, Art 51; Case Concerning the Gabčíkovo-Nagymaros Project (Hungary/Slovakia) (Judgment) 1997 ICJ Rep 7, para 85.
  268. See ILC Articles on State Responsibility, part 3, para 5; see also Tallinn Manual 2.0, commentary to rule 23, para 7.
  269. Government of Canada, International Law applicable in cyberspace (April 2022).
  270. Federal Government of Germany, ‘On the Application of International Law in Cyberspace’, Position Paper (March 2021) 13-14.
  271. Italian Ministry for Foreign Affairs and International Cooperation, ‘Italian position paper on "International law and cyberspace"’ (2021) 7-8.
  272. Ministry of Foreign Affairs of Japan, Basic Position of the Government of Japan on International Law Applicable to Cyber Operations (16 June 2021) 4-5.
  273. Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States, UNODA, A/76/136 (August 2021) 72-73.
  274. Government Offices of Sweden, Position Paper on the Application of International Law in Cyberspace (July 2022) 6.
  275. Federal Department of Foreign Affairs, ‘Switzerland's position paper on the application of international law in cyberspace’ (May 2021) 6-7.
  276. Attorney General Jeremy Wright, Cyber and International Law in the 21st Century (23 May 2018); Attorney General Suella Braverman, International Law in Future Frontiers (19 May 2022).
  277. Brian J Egan, International Law and Stability in Cyberspace (10 November 2016) 21-22; Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States, UNODA, A/76/136 (August 2021) 142.
  278. ILC Articles on State Responsibility, Art 52(3).
  279. ILC Articles on State Responsibility, Art 52(4).
  280. ILC Articles on State Responsibility, Art 53.
  281. ILC Articles on State Responsibility, Art 54. In the cyber context, scholarship supportive of notion of collective countermeasures includes Michael N Schmitt, ‘Estonia Speaks Out on Key Rules for Cyberspace’ (Just Security, 10 June 2019), considering the Estonian interpretation to be “an advantageous development in the catalogue of response options that international law provides to deal with unlawful acts”; see also Michael N Schmitt and Sean Watts, ‘Collective Cyber Countermeasures?’ (2021) 12 Harvard National Security Journal 373. Conversely, scholarship that has rejected this notion includes Jeff Kosseff, ‘Collective Countermeasures in Cyberspace’ (2020) 10(1) Notre Dame Journal of International & Comparative Law 18, 34; François Delerue, Cyber Operations and International Law (CUP 2020), 457.
  282. President of Estonia, Kersti Kaljulaid, ‘President of the Republic at the opening of CyCon 2019’ (29.05.2019); see also Official compendium of voluntary national contributions on the subject of how international law applies to the use of information and communications technologies by States, UNODA, A/76/136 (August 2021) 28.
  283. New Zealand Foreing Affairs and Trade, The Application of International Law to State Activity in Cyberspace (1 December 2020) 3-4.
  284. Michael Schmitt, Three International Law Rules for Responding Effectively to Hostile Cyber Operations (Just Security, 31 July 2021)
  285. French Ministry of the Armies, International Law Applied to Operations in Cyberspace (9 September 2019) 10, arguing that collective countermeasures are not authorised under international law.
  286. Government of Canada, International Law applicable in cyberspace (April 2022) para 37.
  287. ILC Articles on State Responsibility, Commentary in Part 3, Chapter 2 on Art 49, para 3.
  288. ILC Articles on State Responsibility, Commentary to Part One, Chapter 5, para 8 (noting that “[i]n a bilateral dispute over State responsibility, the onus of establishing responsibility lies in principle on the claimant State”).
  289. See, eg, Trail Smelter case (United States v Canada) (Award) 1941 3 RIAA 1905, 1965; see also Robin Geiss and Henning Lahmann, ‘Freedom and Security in Cyberspace: Shifting the Focus Away from Military Responses Towards Non-Forcible Countermeasures and Collective Threat-Prevention’ in Katharina Ziolkowski (ed), Peacetime Regime for State Activities in Cyberspace (NATO CCD COE 2013) 624 (noting that in cases where State responsibility is involved, the required threshold tends to shift towards ‘clear and convincing’”).
  290. James Green, ‘Fluctuating Evidentiary Standards for Self-Defence in the International Court of Justice’ (2009) 58 ICLQ 163, 167 (emphasis original).
  291. ILC Articles on State Responsibility, Commentary in Part 3, Chapter 2 on Art 49 para 3.
  292. Tallinn Manual 2.0, commentary to rule 4, para 18, and to rule 11, para 7.
  293. 293.0 293.1 ILC Articles on State Responsibility, Commentary in Part 3 Chapter 2 on Art 49, para 3.

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