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.

1 Scenario[edit | edit source]

1.1 Keywords[edit | edit source]

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

1.2 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.

1.3 Examples[edit | edit source]

2 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).

2.1 Attribution[edit | edit source]

2.1.1 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 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;[2]
  3. 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."[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: even though they might have been acting on their own (as State B claimed in the aftermath of the incidents), their conduct would still be attributable to State B. 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.[8] 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:

2.1.2 Non-State actors[edit | edit source]

Non-State actors
Activities of non-State actors (groups and individuals) are generally not attributable to States. However, exceptionally such conduct is attributable to a State, in particular in situations when 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";[9]
  2. "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";[10]
  3. "an insurrectional movement which becomes the new Government of a State";[11] or
  4. "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".[12]

Alternatively,

  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".[13]

[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 Draft 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.[14]

  • The arguably most stringent factor of "instructions" would require "State B Digital Army" to be factually subordinate 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 does not suffice for the purposes of attribution of the latter’s conduct to the former.[15]
  • 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".[16] This would imply a continuing relationship of subordination between State B and "State B Digital Army", going the 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 government and private cyber infrastructure in State B is not sufficient.[17] 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.

2.1.3 Evidence[edit | edit source]

Evidentiary standards
Evidentiary standards applicable to the attribution of cyber activities are context-dependent. The law of State responsibility as such does not contain generally applicable burdens, standards, or methods of proof,[18] and these matters are instead ordinarily determined by the relevant forum.[19]

However, 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."[20] 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."[21] Nevertheless, there is no obligation to publicly provide the evidence.[22]

Specific rules may apply to some responses, so when State A responds with countermeasures after misattributing an internationally wrongful act to State B, it commits an internationally wrongful act of its own, even though it correctly applied the "reasonableness" standard of attribution.[23]

[L8] In incidents 1 and 2, State A does not have much information to 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.[24]

2.2 Breach of an international obligation[edit | edit source]

2.2.1 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.[25]

Multiple declarations by the UN,[26] NATO,[27] OSCE,[28] the European Union,[29] and individual States have confirmed that international law applies in cyberspace. Accordingly, so too does the principle of sovereignty. 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[30] and it was reportedly not challenged by any of the over fifty States that participated in the process of consultations regarding the Manual prior to its publication in 2017.[31]
  • 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.[32] This view has now been adopted by one State, the United Kingdom.[33] By this approach, cyber operations never violate the sovereignty of a State, 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).

It is understood that sovereignty has both an internal and an external component.[34] 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.”[35][36]

As a general rule, each State must respect the sovereignty of other States.[37] 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.[38]

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.[39] 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.[40]
  2. Causation of physical damage or injury by remote means;[41] again, “a few” Experts took the position that this is a relevant but not a determinative factor by itself.[42]
  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 operating system or other software was proposed but not universally accepted);[43] 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.[44]
  4. Interference with data or services that are necessary for the exercise of "inherently governmental functions";[45] although the Experts could not conclusively define the term "inherently governmental functions", they agreed that, for example, the conduct of elections would so qualify.[46]
  5. Usurpation of "inherently governmental functions", such as exercise of law enforcement functions in another State’s territory without justification.[47]

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.[48]

[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 ‘physically’ 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[49] and did not require either the replacement of physical components or the reinstallation of the operating system.

[L13] However, the 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.[50] This is regardless of the fact that the affected infrastructure was non-governmental.[51]

2.2.2 Prohibited intervention by State B[edit | edit source]

Prohibition of intervention
The obligation of non-intervention, a norm of customary international law 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 case Nicaragua v United States:

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.[52]

In order for an act, including a cyber operation, to qualify as a prohibited intervention, it must fulfil the following conditions:
  1. The act must bear on those matters in which States may decide freely. The spectrum of such issues is particularly broad and it includes both internal affairs (such as “choice of a political, economic, social, and cultural system”[53]), and external affairs (“formulation of foreign policy”[53])—the so-called domaine réservé of States.[54] 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. However, in the cyber context, the Tallinn Manual 2.0 suggests that “the coercive effort must be designed to influence outcomes in, or conduct with respect to, a matter reserved to a target State”.[55] On that basis, 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)”.[56] This approach distinguishes coercing or compelling the target State from merely influencing it by persuasion or propaganda and from causing nuisance without any particular goal.[57] The element of coercion also entails the requirement of intent.[58]
  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.[59]

[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.[60]

[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.[61] As such, the cyber operations in the scenario do not seem to qualify as a prohibited intervention under international law.

2.2.3 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”.[62] 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”.[63]

It is the matter of some controversy whether the principle of due diligence reflects a binding obligation applicable to cyber operations.[64] 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.[65] 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. This view has also been unanimously endorsed by the drafters of the Tallinn Manual 2.0.[66]

Due diligence does not entail a duty of prevention,[67] but rather an obligation of conduct.[68] 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) contrary to the rights of a victim State,[69]
  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),[70]
  3. which would have been unlawful if conducted by the potentially responsible State,[71]
  4. which have serious adverse consequences for the victim State,[72]
  5. with respect to which the potentially responsible State has actual or constructive knowledge,[73] and
  6. upon which the potentially responsible State can act, but fails to take all feasible measures.[74]

[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 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.[75] 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.[76]

[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.

2.2.4 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.[77]

Multiple declarations by the UN,[78] NATO,[79] OSCE,[80] the European Union,[81] and individual States have confirmed that international law applies in cyberspace. Accordingly, so too does the principle of sovereignty. 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[82] and it was reportedly not challenged by any of the over fifty States that participated in the process of consultations regarding the Manual prior to its publication in 2017.[83]
  • 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.[32] This view has now been adopted by one State, the United Kingdom.[33] By this approach, cyber operations never violate the sovereignty of a State, 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).

It is understood that sovereignty has both an internal and an external component.[84] 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.”[35][85]

As a general rule, each State must respect the sovereignty of other States.[86] 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.[87]

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.[39] 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.[40]
  2. Causation of physical damage or injury by remote means;[88] again, “a few” Experts took the position that this is a relevant but not a determinative factor by itself.[89]
  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 operating system or other software was proposed but not universally accepted);[90] 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.[91]
  4. Interference with data or services that are necessary for the exercise of "inherently governmental functions";[45] although the Experts could not conclusively define the term "inherently governmental functions", they agreed that, for example, the conduct of elections would so qualify.[46]
  5. Usurpation of "inherently governmental functions", such as exercise of law enforcement functions in another State’s territory without justification.[92]

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.[93]

[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. 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.[94]

[L22] State A might be able to justify its actions by invoking countermeasures, as detailed below.

2.3 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”.[95]

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;[96]
  2. The internationally wrongful act has not ceased and “the dispute is [not] pending before a court or tribunal which has the authority to make decisions binding on the parties”, unless the “responsible State fails to implement the dispute settlement procedures in good faith”;[97]
  3. The injured State has called upon[98] the responsible State to fulfil its obligations arising from its internationally wrongful act;[99] and
  4. 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.”[100]

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;[101] in other words, the aim of countermeasures is restoration, not retribution; 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;”[102]
  3. They shall not affect “obligations under peremptory norms of general international law”[103], 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;[104] 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 requirement of “proportionality”).[105]

Taken countermeasures must be suspended if the internationally wrongful act has ceased or if “the dispute is pending before a court or tribunal which has the authority to make decisions binding on the parties”, and they must be terminated as soon as the responsible State has complied with its (secondary) obligations.

Only the injured State may take countermeasures, unless there has been a violation of a norm of erga omnes status. Other States can only take other lawful measures.[106]

Whether a particular measure fulfils these conditions is an objective question,[107] while the burden of proof that the relevant conditions have been fulfilled falls on the injured State.[108] 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 in this regard on the standard of “clear and convincing evidence”.[109] 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.”[110] Importantly, if a State does resort to countermeasures on the basis of an unfounded assessment that a breach has occurred, it may incur responsibility for its own wrongful conduct.[111]

[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.[112])

[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 respond with 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. 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.[113] 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.”[113] Therefore, State A’s countermeasures were lawful: they were done in reaction to an objectively internationally wrongful act of State B.

3 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?

4 Appendixes[edit | edit source]

4.1 See also[edit | edit source]

4.2 Notes and references[edit | edit source]

  1. ILC Articles on State Responsibility, Art 4(1).
  2. ILC Articles on State Responsibility, Art 6.
  3. ILC Articles on State Responsibility, Art 5.
  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, Art 7.
  9. 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.
  10. ILC Articles on State Responsibility, Art 9.
  11. ILC Articles on State Responsibility, Art 10(1).
  12. ILC Articles on State Responsibility, Art 10(2).
  13. ILC Articles on State Responsibility, Art 11.
  14. 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).
  15. 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”).
  16. 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.
  17. Tallinn Manual 2.0, commentary to rule 15, para 13-14.
  18. 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.").
  19. Tallinn Manual 2.0, Chapter 4 Section 1, para 8.
  20. 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.’).
  21. Tallinn Manual 2.0, Chapter 4 Section 1, para 10.
  22. 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'; see also Tallinn Manual 2.0, Chapter 4 Section 1 chapeau, paragraph 13.
  23. 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.”)
  24. 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'.
  25. Island of Palmas (Neth. v. U.S.), 2 RIAA 829, 838 (Perm. Ct. Arb. 1928).
  26. UNGA Res 71/237 (30 December 2015) UN Doc A/RES/20/237.
  27. 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.
  28. 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.
  29. 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),
  30. Michael N Schmitt, 'Virtual Disenfranchisement: Cyber Election Meddling in the Grey Zones of International Law' (2018) 19 ChiJIntlL 30,40; Tallinn Manual 2.0, commentary to rule 4, para 2 (‘States shoulder an obligation to respect the sovereignty of other States as a matter of international law’).
  31. See Michael N Schmitt and Liis Vihul, ‘Respect for Sovereignty in Cyberspace’ (2017) 95 Tex L Rev. 1639, 1649 (noting that States ‘voiced no meaningful objection to Rule 4’ and that ‘it appeared to be received knowledge that a primary rule on territorial-sovereignty violations existed and applied to cyber operations.’).
  32. 32.0 32.1 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’).
  33. 33.0 33.1 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’); see also Memorandum from JM O’Connor, General Counsel of the Department of Defense, ‘International Law Framework for Employing Cyber Capabilities in Military Operations’ (19 January 2017) (considering that sovereignty is not ‘a binding legal norm, proscribing cyber actions by one State that result in effects occurring on the infrastructure located in another State, or that are manifest in another State’), as cited by Sean Watts & Theodore Richard, 'Baseline Territorial Sovereignty and Cyberspace' (2018) 22 Lewis & Clark L. Rev. 771, 829.
  34. Cf. James Crawford, Brownlie's Principles of Public International Law (OUP 2012) 448
  35. 35.0 35.1 Tallinn Manual 2.0, rule 2.
  36. 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.')
  37. 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.
  38. Tallinn Manual 2.0, commentary to rule 4, para 5 and 12.
  39. 39.0 39.1 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.
  40. 40.0 40.1 Tallinn Manual 2.0, commentary to rule 4, para 7; commentary to rule 32, para 9.
  41. Tallinn Manual 2.0, commentary to rule 4, para 11.
  42. Tallinn Manual 2.0, commentary to rule 4, para 12.
  43. Tallinn Manual 2.0, commentary to rule 4, para 13.
  44. Tallinn Manual 2.0, commentary to rule 4, para 14.
  45. 45.0 45.1 Tallinn Manual 2.0, commentary to rule 4, para 15.
  46. 46.0 46.1 Tallinn Manual 2.0, commentary to rule 4, para 16.
  47. Tallinn Manual 2.0, commentary to rule 4, para 18.
  48. In favour: see, eg, 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.
  49. 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).
  50. Tallinn Manual 2.0, commentary to rule 4, para 13.
  51. Tallinn Manual 2.0, commentary to rule 2, para 3.
  52. Military and Paramilitary Activities in and against Nicaragua (Nicaragua v US) (Merits) [1986] ICJ Rep 14, para. 205.
  53. 53.0 53.1 Military and Paramilitary Activities in and against Nicaragua (Nicaragua v US) (Merits) [1986] ICJ Rep 14, para 205.
  54. 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”).
  55. Tallinn Manual 2.0, commentary to rule 66, para 19.
  56. Tallinn Manual 2.0, commentary to rule 66, para 21.
  57. Tallinn Manual 2.0, commentary to rule 66, para 21.
  58. Tallinn Manual 2.0, commentary to rule 66, paras 19, 27.
  59. Tallinn Manual 2.0, commentary to rule 66, para 24 (The exact nature of the causal nexus was not agreed on).
  60. 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.”).
  61. Cf. Tallinn Manual 2.0, commentary to rule 66, para. 21 (“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).”).
  62. Corfu Channel Case (UK v Albania) (Merits) [1949] ICJ Rep 4, 22.
  63. UN GA Res 55/63 (4 December 2000), Doc A/RES/55/63, para 1(a).
  64. 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).
  65. See Luke Chircop, ‘A Due Diligence Standard of Attribution in Cyberspace’ (2018) 67 ICLQ 643.
  66. Tallinn Manual 2.0, commentary to rule 6, para 4.
  67. Tallinn Manual 2.0, commentary to rule 6, para 5.
  68. 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).
  69. Corfu Channel judgment, para 22; Tallinn Manual 2.0, commentary to rule 6, para 2 and 15.
  70. Tallinn Manual 2.0, rule 6.
  71. Tallinn Manual 2.0, commentary to rule 6, para 18-24.
  72. Tallinn Manual 2.0, rule 6.
  73. Tallinn Manual 2.0, commentary to rule 6, para 37-42.
  74. Tallinn Manual 2.0, commentary to rule 6, para 43; commentary to rule 7, para 2 and 18.
  75. Tallinn Manual 2.0, commentary to rule 6, para 40.
  76. Cf. Joanna Kulesza, Due Diligence in International Law (Brill Nijhoff 2016) 53.
  77. Island of Palmas (Neth. v. U.S.), 2 RIAA 829, 838 (Perm. Ct. Arb. 1928).
  78. UNGA Res 71/237 (30 December 2015) UN Doc A/RES/20/237.
  79. 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.
  80. 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.
  81. 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),
  82. Michael N Schmitt, 'Virtual Disenfranchisement: Cyber Election Meddling in the Grey Zones of International Law' (2018) 19 ChiJIntlL 30,40; Tallinn Manual 2.0, commentary to rule 4, para 2 (‘States shoulder an obligation to respect the sovereignty of other States as a matter of international law’).
  83. See Michael N Schmitt and Liis Vihul, ‘Respect for Sovereignty in Cyberspace’ (2017) 95 Tex L Rev. 1639, 1649 (noting that States ‘voiced no meaningful objection to Rule 4’ and that ‘it appeared to be received knowledge that a primary rule on territorial-sovereignty violations existed and applied to cyber operations.’).
  84. Cf. James Crawford, Brownlie's Principles of Public International Law (OUP 2012) 448
  85. 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.')
  86. 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.
  87. Tallinn Manual 2.0, commentary to rule 4, para 5 and 12.
  88. Tallinn Manual 2.0, commentary to rule 4, para 11.
  89. Tallinn Manual 2.0, commentary to rule 4, para 12.
  90. Tallinn Manual 2.0, commentary to rule 4, para 13.
  91. Tallinn Manual 2.0, commentary to rule 4, para 14.
  92. Tallinn Manual 2.0, commentary to rule 4, para 18.
  93. In favour: see, eg, 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.
  94. 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.”
  95. ILC Articles on State Responsibility, Commentary, part 3 ch 2 at para 1.
  96. ILC Articles on State Responsibility, Art 49(1); Case Concerning the Gabčíkovo-Nagymaros Project (Hungary/Slovakia) (Judgment) [1997] ICJ Rep 7, para 83.
  97. ILC Articles on State Responsibility, Art 52(3) – 52(4).
  98. ILC Articles on State Responsibility, Art 52(1)(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’.
  99. 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.
  100. ILC Articles on State Responsibility, Art 52(1)(b) – 52(2).
  101. 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.
  102. ILC Articles on State Responsibility, Art 49(3).
  103. Such as the obligation to refrain from the threat or use of force as embodied in the UN Charter, obligations for the protection of fundamental human rights, and obligations of a humanitarian character prohibiting reprisals. ILC Articles on State Responsibility, Art 50(1).
  104. ILC Articles on State Responsibility, Art 50(2).
  105. Articles on State Responsibility, Art 51; Case Concerning the Gabčíkovo-Nagymaros Project (Hungary/Slovakia) (Judgment) [1997] ICJ Rep 7, para 85.
  106. ILC Articles on State Responsibility, Art 54.
  107. ILC Articles on State Responsibility, Commentary in Part 3, Chapter 2 on Art 49, para 3.
  108. 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”).
  109. 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’”).
  110. James Green, ‘Fluctuating Evidentiary Standards for Self-Defence in the International Court of Justice’ (2009) 58 ICLQ 163, 167 (emphasis original).
  111. ILC Articles on State Responsibility, Commentary in Part 3, Chapter 2 on Art 49, para 3.
  112. Tallinn Manual 2.0, commentary to rule 4, para 18, and to rule 11, para 7.
  113. 113.0 113.1 ILC Articles on State Responsibility, Commentary in Part 3 Chapter 2 on Art 49, para 3.

4.3 Bibliography and further reading[edit | edit source]

4.4 Contributions[edit | edit source]

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