Scenario 30: Backdoors and implants

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Dall-E 3

This scenario considers a series of cyber operations by an acting State which maintains backdoors in the responding State’s networks for later use. The responding State counters by establishing a backdoor in the offending State’s networks and using it to thwart the acting State’s operation. This scenario analyses the rules of State responsibility, including the international obligations that may have been breached, the rules of legal review of cyber weapons, and the possibility of justifying the responding State’s response by the law of countermeasures and self-defence.

Scenario[edit | edit source]

Keywords[edit | edit source]

Backdoors, sovereignty, prohibition of intervention, use of force, countermeasures, legal review of cyber weapons.

Facts[edit | edit source]

[F1] State A and State B are two rival States with a history of tensions. There are currently no hostilities between them. However, State A’s military intelligence service maintains backdoors in several targets in State B:

  • Incident 1: State A exploits zero-day firmware vulnerabilities to access military drones operated by State B. This allows State A to maintain a backdoor in the drones, which can be used to exfiltrate visual data in real-time, take control of the drones, or crash them.
  • Incident 2: Additionally, State A uses zero-day vulnerabilities in the firmware of programmable logic controllers (PLCs) of energy distribution networks in State B to open backdoors, which can be used to implant malware designed to cause large-scale blackouts affecting 20 percent of State B’s population.
  • Incident 3: State A also maintains backdoors in State B’s Ministry of Foreign Affairs servers open to the internet, which it can use to execute a payload for editing and defacing the Ministry’s website.

[F2] In parallel, State B’s military intelligence service has infiltrated the command-and-control infrastructure of State A’s military intelligence service. State B maintains an active backdoor in the infrastructure, closely observing the activities of State A by exfiltrating data (incident 4). State A decides to use the backdoors in State B to achieve the effects described in incidents 1 to 3 (take control of and crash the drones; cause the blackout; deface the Ministry’s website) (incident 5). However, before the operation is executed, State B uses its backdoor in State A to implant malware which encrypts the command and control infrastructure of State A’s military intelligence service (incident 6), thereby thwarting the attempted operation by State A. Complete reinstallation of all data, including operating system, on the command and control infrastructure, is required.

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] After a very brief treatment of attribution, the legal analysis focuses on possible breaches of State A’s international obligations (sovereignty, prohibition of intervention, use of force) and the legality and possible justification for State B’s response (countermeasures, self-defence). It also covers the questions of cyber espionage and cyber weapons review with respect to establishing and using backdoors.

Attribution[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] All of the incidents are clearly attributed by the fact description to State A’s and State B’s military intelligence services. Both State A’s and State B’s military intelligence services are state organs exercising an executive function, irrespective of the legality of their conduct under national or international law.[5] Therefore, their conduct is attributable to the States in question.

Breach of an international obligation[edit | edit source]

Sovereignty[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.[6]

Multiple declarations by the UN,[7] the African Union,[8] the European Union,[9] NATO,[10] OSCE,[11] and individual States have confirmed that international law applies in cyberspace. Accordingly, so too does the principle of sovereignty.[12] 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.[13] It has also been adopted by several States including Austria,[14] Brazil, [15] Canada,[16] the Czech Republic,[17] Estonia,[18] Finland,[19] France,[20] Germany,[21] Iran,[22] Italy,[23] Japan,[24] the Netherlands,[25] New Zealand,[26] Norway,[27] Romania[28] and Sweden.[29]
  • 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.[30] This view has been adopted by one State, the United Kingdom,[31] and has been partially endorsed by the U.S. Department of Defense General Counsel.[32] 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.[33] 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.”[34][35] This encompasses both private and public infrastructure.[36] The external component entails that States are “free to conduct cyber activities in [their] international relations”, subject to their international law obligations.[37]

As a general rule, each State must respect the sovereignty of other States.[38]However, within the cyber realm – and particularly regarding remote cyber operations – there is still no agreement on the criteria[39] and the required threshold[40] to qualify an operation as a sovereignty violation.[41] 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.[42] Accordingly, the assessment needs to be done on a case-by-case basis.[43]

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.[44] 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.[45]
  2. Causation of physical damage or injury by remote means;[46] again, “a few” Experts took the position that this is a relevant but not a determinative factor by itself.[47]
  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);[48] 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.[49]
  4. Interference with data or services that are necessary for the exercise of "inherently governmental functions";[50] although the Experts could not conclusively define the term "inherently governmental functions", they agreed that, for example, the conduct of elections would so qualify.[51]
  5. Usurpation of "inherently governmental functions", such as exercise of law enforcement functions in another State’s territory without justification.[52]

The Tallinn Manual’s view of what constitutes a violation of sovereignty has been expressly endorsed by several States including Canada,[53] Germany[54] and the Netherlands;[55] and followed to some extent by other States, such as the Czech Republic,[56] Norway,[57] Sweden[58] and Switzerland.[59] 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”;[60]similarly, Iran has argued that “unlawful intrusion to the (public or private) cyber structures” abroad may qualify as a breach of sovereignty.[61]

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.[62]

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 Austria (2024) (2024), 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 the Czech Republic (2024) (2024), 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).

[L3] As regards incidents 1 to 4, no individual whose conduct was attributable to State A was physically present in the territory of State B and vice versa. Malware itself cannot be considered as an organ or other agent of a State. The Experts drafting the Tallinn Manual 2.0 agreed that this option only applied to physical incursion of an individual into the territory of another State.[63] Also, no actual physical damage or loss of functionality was caused by incidents 1 to 4, because mere installation of backdoors (and the accompanying exfiltration of data) is below the threshold of loss of functionality.[64] Interference with inherently governmental functions is not applicable to any of the incidents, even though incidents 1 and 4 deserve a closer look: defence is an inherently governmental function, and even though the security of military drones and hence also their military value are interfered with by the mere opening of the backdoor, the operation has no direct effect on their functioning at the moment. Neither do any of the incidents qualify as a usurpation of an inherently governmental function.

[L4] The analysis of incident 5 (specifically, the attempted takeover of the drones and the attempted blackout) is complicated by the fact that the threat did not fully materialize. State A attempted to make use of the maintained backdoors, but the attempt was thwarted by State B. A possible interpretation is that if the effects intended by State A in incident 5 did materialize, then they would clearly amount to a violation of sovereignty (physical damage due to the destruction or capture of drones, possibly the large-scale loss of functionality due to the power outage; and interference with national defence, foreign relations, and energy supply which is heavily regulated both domestically and internationally). However, as the attempt was thwarted, it did not constitute an internationally wrongful act in itself by way of violation of sovereignty.[65]

[L5] An alternative view of the attempt in incident 5 would be that an act already “occurs” once the specific action is executed, i.e. when the decision to activate the payload is taken, even if the effects do not materialize. “Preparatory conduct does not itself amount to a breach if it does not 'predetermine the final decision taken'”.[66] However, the decision to execute the payload has already been taken, which would lead to the harmful effect. Therefore, on that view, a violation has occurred.

[L6] No physical presence or physical damage is involved in incident 6. Loss of functionality was caused by State B’s actions in incident 6 (encryption of the command-and-control infrastructure of State A’s military intelligence service). This loss of functionality would necessitate the replacement of hardware or at least the reinstallation of the operating system on the targeted devices. Therefore, the action of State B breached the sovereignty of State A. This conclusion is without prejudice to the question whether a justification exists that would preclude the wrongfulness of this action (see paras L16–L23 below).

[L7] Military intelligence is a function of a State which cannot be engaged in by a non-State actor, and hence it is considered as an inherently governmental function.[67] Therefore, the action of State B in incident 6 disabling the capability constitutes an interference with an inherently governmental function. Again, this conclusion is without prejudice to the question whether a justification exists that would preclude the wrongfulness of this action (see paras L16–L23 below).

Prohibition of intervention[edit | edit source]

Prohibition of intervention
The obligation of non-intervention, a norm of customary international law,[68] 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.[69]

In order for an act, including a cyber operation,[70] to qualify as a prohibited intervention, it must fulfil the following conditions:[71]
  1. The act must bear on those matters in which States may decide freely.[72] 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”[69] or the conduct of national elections[73]), and external affairs (“formulation of foreign policy”;[69] or “recognition of states and membership of international organisations”[74])—the so-called domaine réservé of States.[75] 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:[76]
    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.[77] 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)”.[78]
    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.[79] 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.[80]
    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.[81] The element of coercion also entails the requirement of intent.[82]

    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,[83] it is less clear with respect to non-forcible forms of interference.[84] Some States support the approach that intervention may take various forms, such as economic and political coercion.[85] One example that has been reiterated in several States’ positions, including Australia,[86] Brazil,[87] Canada,[88] Germany,[89] Israel,[90] New Zealand,[91] Norway,[92] Singapore,[93] the United Kingdom[94] and the United States,[95] 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.[96]

    Both potential and actual effects are considered to be relevant when assessing the coercion element.[97]

  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.[98]

    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.[99]


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 Austria (2024) (2024), 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 (2024) (2024), 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).

[L8] Incidents 1 through 6 interfere with the target State’s domaine réservé, as they bear on matters in which the target State may decide freely. Incident 1 affects national defence of State B; incident 2 affects national electrical power distribution (generally seen as part of a State’s critical infrastructure)[100] and, depending on the circumstances, also national defence of State B; incident 3 has a bearing on the conduct of external relations of State B; and incident 4 is targeted against the military intelligence (national defence) of State A. The intended results of incidents 5 and 6 are the realization of the danger posed by the backdoors described in incidents 1 through 4, so they also interfere with the domaine réservé.

[L9] However, their level of coerciveness varies. According to one interpretation, the mere establishment of backdoors in incidents 1 through 4 does not compel the target State to change its behaviour nor deprives it of control over the protected matter, so these activities would not constitute coercion. The alternative interpretation is that the target State would need to take actions to defend its systems from the threats posed by the backdoors once it finds out. This effectively coerces State B to defend its systems or bear even more serious coercive consequences. For the present author, the latter interpretation is more convincing, because the security of certain critical systems is impacted by the mere opening of the backdoor (analogical argument to interference with inherently governmental functions in L3). Of course, this approach would entail the need to identify a threshold below which such incidents would not coerce the target State to prevent the consequences.

[L10] Nevertheless, the attempt at causing the effects in incident 5 (specifically, the control of drones and the power outage) is clearly coercive, as it is meant to deprive State B of control over its military equipment and the power grid. In this case, the fact that it is a mere attempt without actual effects might not prevent its qualification as prohibited intervention – State A effectively coerced State B to defend its systems or bear even more serious coercive consequences.

[L11] Incident 6 deprives State A of control over its government infrastructure and is intended to stop the operation described in incident 5, so it is clearly coercive by State B. This conclusion is without prejudice to the question whether a justification exists that would preclude the wrongfulness of this action (see paras L16–L23 below).

Use of force[edit | edit source]

Use of force
Article 2(4) of the UN Charter prescribes States to “refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the purposes of the United Nations”.[101] This prohibition is reflective of customary international law[102] and it is frequently described as a peremptory norm of international law.[103]

This rule applies between States; therefore the conduct needs to be attributable to a State and against another State ‘in their international relations’, thus excluding non-State actors unless their conduct is attributable to a State.[104]

As stated by the International Court of Justice, the prohibition applies to any use of force, regardless of the means employed.[105] However, the notion of “force” in this context is limited to armed force[106], and to operations whose scale and effects are comparable to the use of armed force.[107] As stressed by several States, each situation has to be analysed on a case-by-case basis.[108]

Undoubtedly, one of the purposes of the prohibition of force under international law is to safeguard the national security of the potentially affected States.[109] However, many forms of outside interference including various forms of political and economic coercion may affect the national security of the victim State. And yet, the drafters of the UN Charter had expressly rejected the proposal to extend the prohibition of force beyond the strict confines of military (or armed) force.[110] This is reflected also in the preamble, which explicitly stipulates that the drafters sought “to ensure, by the acceptance of principles and the institution of methods, that armed force shall not be used, save in the common interest”.[111]

In principle, it could be argued that the notion of “force”, like other generic terms in treaties of unlimited duration, should be presumed to have an evolving meaning.[112] Regarding its application to cyber operations, an “effects-based approach” has been mostly followed.[113] In this sense, there is emerging consensus that “a cyber attack that causes or is reasonably likely to cause physical damage to property, loss of life or injury to persons would fall under the prohibition contained in Article 2(4) of the UN Charter”,[114] including both direct and indirect consequences. At present, there is a debate as to whether cyber operations with no physical effects may amount to a prohibited use of force. It has been argued that disruptive cyber operations of this kind fall under the scope of Article 2(4) if the resulting disruption is “significant enough to affect state security”.[115]

As of 2022, there is limited State practice supporting the claim that the meaning of “force” has evolved to include non-destructive cyber operations against critical national infrastructure[116] and no victim State of an operation of this kind has suggested that the operation would have amounted to a use of force.[117] However, States have begun addressing this question. In particular, France,[118] the Netherlands[119] and Norway[120] allow for the possibility of cyber operations, which do not produce physical effects, to qualify as uses of force, if certain criteria are met. These qualitative and quantitative non-exhaustive criteria include the seriousness and reach of a given cyber operation’s consequences and its military nature,[121] as well as “the circumstances prevailing at the time of the operation, such as the origin of the operation and the nature of the instigator (military or not), the extent of intrusion, the actual or intended effects of the operation or the nature of the intended target”.[122] Several of these criteria are also reflected in the Tallinn Manual 2.0.[123] Other States, such as Italy, did not rule out the possibility of considering operations causing the interruption of essential services without physical damage within the scope of the prohibition of the use of force.[124]

A use of force is unlawful under international law, unless it is authorized by the UN Security Council under Chapter VII of the UN Charter,[125] conducted in the exercise of the inherent right to self-defence,[126] or consented to by the territorial State.[127]

Even if an operation does not meet the threshold of the use of force, it may still be considered a violation of other rules of international law.[128] In this regard, the prohibition of intervention, the obligation to respect the sovereignty of other States, and the possible obligation to refrain from launching cyber operations against other States’ critical infrastructure are all of potential relevance.

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 Austria (2024) (2024), National position of Brazil (2021) (2021), National position of Canada (2022) (2022), National position of Costa Rica (2023) (2023), National position of the Czech Republic (2024) (2024), National position of Denmark (2023) (2023), 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 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 the Kingdom of Sweden (2022) (2022), National position of the United Kingdom (2021) (2021), National position of the United States of America (2012) (2012), National position of the United States of America (2020) (2020), National position of the United States of America (2021) (2021).

[L12] Incidents 1 to 4 did not cause and were not reasonably likely to cause physical damage to property, loss of life or injury to persons, including through their direct and indirect consequences. Nor were they significant enough to affect state security by causing effects that would be analogous to a kinetic use of force.[129] They therefore did not amount to a use of force as understood in international law.

[L13] Incident 5 (control of drones) is an attempted use of force, because the takeover of the drones would mean their destruction or capture by the adversary. The second part of incident 5 (attempted power outage), if realized, may constitute use of force if the power outage had the potential to cause physical damage or injury, either directly, or due to cascading effects. The third part of incident 5 (attempted website defacement) is neither a use of force nor a threat of force unless the defacement placed credible and attributable written threats on the website.

[L14] Depending on the potential scale and effects of incident 5 (control of drones and power outage), it might amount to an imminent armed attack to which State B might react in self-defence (see para. L23 below).

[L15] Incident 6 targets the command-and-control infrastructure of the malware; unless the disabling of the infrastructure would cause a spillover effect, it could not cause physical damage to property or be significant enough to affect state security by causing effects that would be analogous to a kinetic use of force.

Response of State B[edit | edit source]

Countermeasures[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”.[130] Several States, including Australia,[131] Austria,[132] Canada,[133] Estonia,[134] France,[135] Germany,[136] Italy,[137] Japan,[138] the Netherlands,[139] New Zealand,[140] Norway,[141] Singapore,[142] Sweden,[143] the United Kingdom,[144] and the United States,[145] have expressly confirmed the applicability of the law of countermeasures to cyber operations. Others, including Brazil,[146] China,[147] and Cuba,[148] 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.[149] 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[150] the responsible State to fulfil its obligations arising from its internationally wrongful act;[151] 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.”[152] Some States, such as Canada,[153] Israel,[154] Norway,[155] the United Kingdom[156] and the United States[157] 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.[158]

Additionally, the countermeasures must fulfil the following requirements:

  2. Their aim must be to induce the responsible State to comply with the legal consequences of its internationally wrongful act;[159] hence, the aim of countermeasures is restoration, not retribution or retaliation; and the countermeasures can only target the responsible State;
  3. They “shall, as far as possible, be taken in such a way as to permit the resumption of performance of the obligations in question”;[160]
  4. They shall not affect the obligation to refrain from the threat or use of force,[161] obligations for the protection of fundamental human rights, of a humanitarian character prohibiting reprisals, or other “obligations under peremptory norms of general international law”;[162] 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;[163] and
  5. 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).[164] However, proportionality does not require that the adopted measures must be equivalent, reciprocal or even in kind.[165] As clearly expressesd by many States, including Canada,[166] Germany,[167] Italy,[168] Japan,[169] Norway,[170] Sweden,[171] Switzerland,[172] the United Kingdom[173] and the United States,[174] 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,[175] except if the responsible State fails to implement the dispute settlement procedures in good faith.[176] Countermeasures must also be terminated as soon as the responsible State has complied with its (secondary) obligations.[177]

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").[178] In particular, Estonia has opined that non-injured States “may apply countermeasures to support the state directly affected by the malicious cyber operation”,[179] a view that has also received some support from New Zealand.[180] 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.[181] However, this view has since been rejected by at least one State (France),[182] 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”.[183] 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,[184] while the burden of proof that the relevant conditions have been fulfilled falls on the injured State.[185] 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”.[186] 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”.[187] 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.[188]

Publicly available national positions that address this issue include: National position of Australia (2020) (2020), National position of Austria (2024) (2024), National position of Brazil (2021) (2021), National position of Canada (2022) (2022), National position of Costa Rica (2023) (2023), National position of the Czech Republic (2024) (2024), 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).

[L16] State B could argue that the operation described in incident 6 amounts to a lawful countermeasure.

[L17] There is a prior internationally wrongful act of State A (violation of sovereignty in incident 1; and prohibited intervention and a use of force in incident 5).

[L18] State A’s operation in incident 5 is imminent, so it is necessary for State B to act immediately in order to preserve its rights.[189] State B is therefore taking urgent countermeasures and it does not have to notify State A in advance, because this would defeat the purpose of the countermeasures. The obligation of State B to call upon State A to fulfil its obligations remains unaffected,[190] but it also should not be construed as a prior requirement because this would have a similar effect as a prior notification and hence would also undermine the efficiency of the countermeasures.[191]

[L19] State B can argue that the aim of the countermeasures is to make State A comply with the legal consequences of its internationally wrongful act (cessation, non-repetition, and reparation). Due to State B’s operation, State A was forced to cease its operation and will not be able to repeat it anytime soon. There is no information about any goals of State B’s operation that would be retaliatory or would otherwise go beyond the legal limits of countermeasures.

[L20] The countermeasures are theoretically reversible; in the case that State A would comply with its international obligations, State B can decrypt the targeted systems, although this is unlikely to be demanded by State A in practice.

[L21] The countermeasures do not violate any peremptory norms or obligations arising from diplomatic or consular inviolability and they do not reach the level of threat or use of force.

[L22] They are commensurate with the potential injury suffered. Disabling the military intelligence systems of State A has a detrimental effect on its national defence, but it is not out of proportion with the effect intended by State A in its attempted operation (takeover of drones and power outage).

Self-defence[edit | edit source]

Self-defence
A State may respond with force to a cyber operation that qualifies as an “armed attack” pursuant to the customary right to self-defence, as codified in Article 51 of the UN Charter. Most commentators consider only grave uses of force – typically, those that kill or injure persons or damage or destroy property – to constitute armed attacks.[192]

The United States, however, takes an outlier position, consistently arguing that any illegal use of force gives rise to the use of force in self-defence.[193]

In Nicaragua, the ICJ identified “scale and effects” as criteria upon which to judge whether a use of force constitutes an armed attack. In the Court’s view, only “the most grave” uses of force do so.[194] Thus, only cyber operations that seriously injure or kill a number of persons or cause significant damage to, or destruction of, property would undoubtedly constitute armed attacks.[195]

Publicly available national positions that address this issue include: National position of Australia (2020) (2020), National position of Austria (2024) (2024), National position of Brazil (2021) (2021), National position of Canada (2022) (2022), National position of Denmark (2023) (2023), 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 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 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 States of America (2012) (2012), National position of the United States of America (2020) (2020), National position of the United States of America (2021) (2021).

[L23] The anticipated effects of incident 5, if materialized, might be serious enough to be considered as a use of force. However, the category of armed attack is reserved for the most grave uses of force, and the only instance of use of force (potential control and destruction of drones) may or may not be grave enough, depending, again, on the anticipated effects. If the anticipated effects were deemed to be serious enough, State B would be entitled to anticipatory self-defence to an imminent armed attack.

Legal review of cyber weapons[edit | edit source]

Legal review of cyber weapons, means and methods of warfare
The requirement that the legality of all new weapons, means and methods of warfare be systematically assessed is arguably one that applies to all States. It flows logically from the truism that States are prohibited from using illegal weapons, means and methods of warfare or from using weapons, means and methods of warfare in an illegal manner.[196] It is also widely considered, including by the ICRC, that a requirement to carry out legal reviews of new weapons, means and methods of warfare also flows from the obligation to ensure respect for IHL.[197] In addition, with respect to State parties to Additional Protocol I, Article 36 of that instrument mandates that “[i]n the study, development, acquisition or adoption of a new weapon, means or method of warfare,” States must determine whether its employment would, in some or all circumstances, be prohibited under IHL or any other applicable rule of international law.[198] It has been argued that the Article 36 obligation represents customary international law,[199] but this view is not universally accepted.[200]

The mere fact of a weapon’s novelty or its reliance on new technology does not automatically mean that the weapon is illegal.[201] Similarly, the lack of general practice by States in using the new weapon is irrelevant as to its legality under IHL.[202] In determining the weapon’s lawfulness, the State in question must therefore assess those rules of IHL, which are binding on the State – be they treaty-based or customary.[203] Additionally, all States remain subject to the so-called Martens Clause,[204] which reinforces the notion that the lawfulness of a new weapon must be assessed under customary international law according to the principles of humanity and the requirements of public conscience.[205] It is unsettled whether this consideration must take the form of a formal legal review.[206] Nevertheless, legal review of new weapons conducted at the earliest possible stage is a critical measure to ensure compliance with the applicable IHL rules. It also helps prevent the costly consequences of approving and procuring a weapon the use of which is likely to be restricted or prohibited.[207]

Although the precise definition of a “cyber weapon” is unsettled as yet,[208] at the very least, all cyber tools capable of conducting “attacks” as understood in IHL, that is, acts of violence against the adversary whether in offence or in defence,[209] should be considered to qualify as cyber weapons,[210] thus falling under the principle that IHL applies to “all forms of warfare and to all kinds of weapons, those of the past, those of the present and those of the future”.[211] For State parties to Additional Protocol I, the obligation extends to the early stages of studying and developing a new cyber capability, be it a cyber weapon, means or method of warfare; these States must conduct a legal review; and the scope of the applicable legal framework includes the entirety of international law, not just the rules of IHL.[212]

In reviewing the lawfulness of a new weapon, means or method of warfare, States must first consider whether its employment is specifically prohibited or restricted by treaty-based or customary IHL.[213] Although no prohibitions of this kind exist at present with respect to cyber capabilities, this may well change in the future. In particular, there is recurring talk of States entering into “cyber arms control treaties” or agreeing to specific limitations on the development and use of cyber offensive capabilities. If formulated as binding prohibitions, these may prevent States from utilizing capabilities falling under the remit of such rules.

If no specific prohibition or restriction is found to apply, the cyber weapon, means or method of warfare in question must be assessed in light of the general prohibitions or restrictions under IHL that bind the State, be they treaty-based or customary. These include, in particular, the prohibition of weapons, means and methods of warfare that are of a nature to cause superfluous injury or unnecessary suffering[214] and the prohibition of means and methods of warfare that are by nature indiscriminate.[215] In addition, a weapon or means of warfare cannot be assessed in isolation from the manner in which it is expected to be used in the battlefield. States should therefore determine if the employment of a weapon for its normal or expected use would be prohibited by IHL under some or all circumstances.[216]

Publicly available national positions that address this issue include: National position of Brazil (2021) (2021), National position of Brazil (2021) (2022), National position of Costa Rica (2023) (2023), National position of the Czech Republic (2024) (2024), National position of Germany (2021) (2021), National position of Switzerland (2021) (2021), National position of the United States of America (2012) (2012),

[L24] The malware used by State A and State B to establish and maintain backdoors, and the payload used by States A and B to cause the effects intended in incidents 5 and 6, would likely be subject to review and other requirements of Article 36 of Additional Protocol I as a weapon or other means or methods of warfare (if they cause physical destruction or loss of functionality or have other effects on the adversary in their normal or expected use). Any internal guidance on the use of the malware in a possible armed conflict could be regarded as a method of warfare and should likewise be subject to review. The fact that State A and State B are not currently in an armed conflict does not invalidate the obligation.

[L25] The malware is meant to target military systems and critical infrastructure, and hence it would be important to ensure its proper targeting and effect. Both State A and State B must consider possible indiscriminate effect of the malware, such as its uncontrollable spreading and side effects on the civilian population and protected objects.[217]

Checklist[edit | edit source]

  • What was the method of establishing and maintaining the backdoor?
  • Did the operation cause a loss of computer, network, or off-network functionality?
  • Did the operation target diplomatic or consular correspondence?
  • Did the operation affect the domaine réservé of the target State?
  • Was the operation coercive?
  • Is this an example of an operation which would qualify as a prohibited intervention but not as a violation of sovereignty?
  • Was the effect of the operation equivalent to a kinetic use of force?
  • Were all the conditions and requirements for launching countermeasures met?
  • Was a legal review in accordance with Article 36 AP I required for the use of a cyber capability?
  • Did the operation affect an inherently governmental function?

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. ↑ ILC Articles on State Responsibility with commentaries, commentary to Article 4, para 13; and Article 7.
  6. ↑ Island of Palmas (Neth. v. U.S.), 2 RIAA 829, 838 (Perm. Ct. Arb. 1928).
  7. ↑ UNGA Res 71/237 (30 December 2015) UN Doc A/RES/20/237.
  8. ↑ 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).
  9. ↑ 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).
  10. ↑ 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.
  11. ↑ 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.
  12. ↑ 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).
  13. ↑ 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’).
  14. ↑ 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’.
  15. ↑ 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.
  16. ↑ Government of Canada, International Law applicable in cyberspace (April 2022) para 13.
  17. ↑ 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.’
  18. ↑ 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.
  19. ↑ 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.’
  20. ↑ 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’.
  21. ↑ 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’.
  22. ↑ 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.’).
  23. ↑ Italian Ministry for Foreign Affairs and International Cooperation, ‘Italian position paper on “International law and cyberspace”’ (2021) 4.
  24. ↑ Ministry of Foreign Affairs of Japan, ‘Basic Position of the Government of Japan on International Law Applicable to Cyber Operations’ (16 June 2021) 3.
  25. ↑ 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’.
  26. ↑ New Zealand Foreign Affairs and Trade, ‘The Application of International Law to State Activity in Cyberspace’ (1 December 2020) 2.
  27. ↑ 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.
  28. ↑ 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.
  29. ↑ Government Offices of Sweden, ‘Position Paper on the Application of International Law in Cyberspace’ (July 2022) 2.
  30. ↑ 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’).
  31. ↑ 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.
  32. ↑ 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’.
  33. ↑ Cf. James Crawford, Brownlie's Principles of Public International Law (OUP 2012) 448.
  34. ↑ Tallinn Manual 2.0, rule 2.
  35. ↑ 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.
  36. ↑ Tallinn Manual 2.0., commentary to rule 4, para 5. See also the national positions of Norway, Sweden and Switzerland.
  37. ↑ Tallinn Manual 2.0., rule 3; see also the national positions of the Czech Republic, the Netherlands and Norway.
  38. ↑ 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.
  39. ↑ 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.
  40. ↑ 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.
  41. ↑ Michael Schmitt, ‘Sovereignty, Intervention, and Autonomous Cyber Capabilities’ (2020) 96 International Law Studies 549.
  42. ↑ Tallinn Manual 2.0, commentary to rule 4, para 5 and 12.
  43. ↑ See e.g. the national position of Canada, Finland, New Zealand, Norway, Sweden and Switzerland.
  44. ↑ 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.
  45. ↑ 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.
  46. ↑ Tallinn Manual 2.0, commentary to rule 4, para 11.
  47. ↑ Tallinn Manual 2.0, commentary to rule 4, para 12.
  48. ↑ 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.
  49. ↑ Tallinn Manual 2.0, commentary to rule 4, para 14.
  50. ↑ Tallinn Manual 2.0, commentary to rule 4, para 15.
  51. ↑ 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.
  52. ↑ Tallinn Manual 2.0, commentary to rule 4, para 18.
  53. ↑ Government of Canada, International Law applicable in cyberspace (April 2022) para 13.
  54. ↑ Germany, ‘On the Application of International Law in Cyberspace: Position Paper’ (March 2021), p. 4.
  55. ↑ Dutch Ministry of Foreign Affairs, ‘Letter to the parliament on the international legal order in cyberspace’ (5 July 2019), p. 3.
  56. ↑ Richard Kadlčák, Statement of the Special Envoy for Cyberspace and Director of Cybersecurity Department of the Czech Republic (11 February 2020) 3.
  57. ↑ 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.
  58. ↑ Government Offices of Sweden, Position Paper on the Application of International Law in Cyberspace (July 2022) 2
  59. ↑ Federal Department of Foreign Affairs, ‘Switzerland's position paper on the application of international law in cyberspace’ (May 2021) 3.
  60. ↑ Ministry of Defense of France, 'International Law Applied to Operations in Cyberspace' (9 September 2019) 6.
  61. ↑ 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’).
  62. ↑ 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’).
  63. ↑ Tallinn Manual 2.0, commentary to Rule 4, para 6.
  64. ↑ Tallinn Manual 2.0, commentary to Rule 4, para 14.
  65. ↑ ILC Articles on State Responsibility with commentaries, commentary to Article 14, para 13. The Articles on State Responsibility neither explicitly define an “attempt” nor consider its illegality, but the commentary states that “attempt[s]” have to be considered with reference to the primary rules in question (e.g. sovereignty). Unless the particular primary rule prohibits attempts as such, as is the case with the prohibition of genocide or certain terrorism offences, then attempts do not constitute internationally wrongful acts.
  66. ↑ ILC Articles on State Responsibility with commentaries, commentary to Article 14, para 13.
  67. ↑ Tallinn Manual 2.0, commentary to Rule 4, para 17.
  68. ↑ The customary nature has been highlighted by several States, including Australia, Brazil, Germany, Iran, Norway, Sweden, the United Kingdom and the United States.
  69. ↑ 69.0 69.1 69.2 Military and Paramilitary Activities in and against Nicaragua (Nicaragua v US) (Merits) [1986] ICJ Rep 14 [205].
  70. ↑ 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).
  71. ↑ 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.
  72. ↑ Militarv and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America) Merits, Judgment. I.C.J. Reports 1986, 14 [241].
  73. ↑ 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.
  74. ↑ 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.
  75. ↑ 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].
  76. ↑ 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.
  77. ↑ 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.’).
  78. ↑ 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.
  79. ↑ 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.’).
  80. ↑ 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.
  81. ↑ Tallinn Manual 2.0, commentary to rule 66, para 21. See also the national positions of Canada, Germany and Norway.
  82. ↑ Tallinn Manual 2.0, commentary to rule 66, paras 19 and 27. See also the national positions of Germany, New Zealand and Sweden.
  83. ↑ 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.
  84. ↑ See Harriet Moynihan, The Application of International Law to State Cyberattacks Sovereignty and Non-Intervention (Chatham House, 2 December 2019) para 82.
  85. ↑ 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’).
  86. ↑ Australian Government, Australia's position on how international law applies to State conduct in cyberspace (2020).
  87. ↑ 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.
  88. ↑ Government of Canada, International Law applicable in cyberspace (April 2022)
  89. ↑ Federal Government of Germany, ‘On the Application of International Law in Cyberspace’, Position Paper (March 2021) 5-6.
  90. ↑ Roy Schöndorf, Israel’s Perspective on Key Legal and Practical Issues Concerning the Application of International Law to Cyber Operations (8 December 2020).
  91. ↑ New Zealand Foreign Affairs and Trade, The Application of International Law to State Activity in Cyberspace (1 December 2020) 2.
  92. ↑ 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.
  93. ↑ 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.
  94. ↑ 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.
  95. ↑ 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.
  96. ↑ See the national positions of Canada, Romania, Sweden and Switzerland.
  97. ↑ 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.
  98. ↑ Tallinn Manual 2.0, commentary to rule 66, para 24 (the exact nature of the causal nexus was not agreed on).
  99. ↑ 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’).
  100. ↑ Some authors have expressed the opinion that electrical power distribution is not necessarily part of a State’s domaine réservé, as the distribution companies may be privately owned. However, this opinion has not been supported by any official State position on the applicability of international law to cyberspace. On the contrary, New Zealand, Norway and the United Kingdom have all explicitly stated that a cyber operation disrupting power distribution may qualify as a prohibited intervention, with Estonia and Japan considering critical infrastructure more broadly [link to PoI in the Toolkit].
  101. ↑ Charter of the United Nations (adopted 26 June 1945, entered into force 24 October 1945) 1 UNTS 16 (UN Charter) art. 2(4).
  102. ↑ Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory (Advisory Opinion) [2004] ICJ Rep 136, para 87; Military and Paramilitary Activities in and against Nicaragua (Nicaragua v United States of America) (Merits) [1986] ICJ Rep 14, paras 187–190. See also, the national positions of Brazil, Israel, Sweden, and the United States.
  103. ↑ See, for example,The International Law Commission, 'Document A/6309/ Rev.1: Reports of the International Law Commission on the second part of its seventeenth and on its eighteenth session' Yearbook of the International Law Commission Vol. II (1966) 247 (“The law of the Charter concerning the prohibition of the use of force in itself constitutes a conspicuous example of a rule in international law having the character of jus cogens”); Christine Gray, International Law and the use of force (OUP 2018) 32; Oliver Corten, The Law against War. The Prohibition on the Use of Force in Contemporary International Law (Hart Pub. 2021) 44; Oliver Dörr and Albrecgr Randelzhofer, ‘Article 2(4)’ in Bruno Simma et al (eds), The Charter of the United Nations: A Commentary Vol I (OUP 2012), 231, para 67 (“the prohibition of the use of force laid down in Art. 2 (4) is usually acknowledged in State practice and legal doctrine to have a peremptory character, and thus to be part of the international ius cogens”).
  104. ↑ Marco Roscini, Cyber Operations and the Use of Force in International Law (Oxford University Press 2014) 44.
  105. ↑ Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion, 1. C.J. Reports 1996, 226; see also the national positions of Brazil, Germany, France, the Netherlands and Sweden.
  106. ↑ Oliver Dörr and Albrecht Randelzhofer, ‘Article 2(4)’ in Bruno Simma et al (eds), The Charter of the United Nations: A Commentary Vol I (OUP 2012) 208 para 16 (“The term [‘force’] does not cover any possible kind of force, but is, according to the correct and prevailing view, limited to armed force.”).
  107. ↑ Cf. Ian Brownlie, International Law and the Use of Force by States (OUP 1963) 362 (“[Art 2(4)] applies to force other than armed force”); Tallinn Manual 2.0, rule 69 (“A cyber operation constitutes a use of force when its scale and effects are comparable to non-cyber operations rising to the level of a use of force.”). This is also embodied in the national positions of several States, including Australia, Canada, Germany, Italy, the Netherlands, Romania and Sweden.
  108. ↑ See the national positions of Canada, Germany, Italy, the Netherlands, Romania, Sweden and the United States.
  109. ↑ Cf. Charter of the United Nations (adopted 26 June 1945, entered into force 24 October 1945) 1 UNTS 16 (UN Charter) art. 2(4) (expressly prohibiting the use of force against the “political independence” of any State).
  110. ↑ Documents of the United Nations Conference on International Organization (1945), vol VI, 334. See also the national position of the Netherlands.
  111. ↑ Charter of the United Nations (adopted 26 June 1945, entered into force 24 October 1945) 1 UNTS 16 (UN Charter) preamble.
  112. ↑ Cf. Dispute regarding Navigational and Related Rights (Costa Rica v Nicaragua) Judgment, 2009 ICJ Rep 213 [66] (“[W]here the parties have used generic terms in a treaty, the parties necessarily having been aware that the meaning of the terms was likely to evolve over time, and where the treaty has been entered into for a very long period or is ‘of continuing duration’, the parties must be presumed, as a general rule, to have intended those terms to have an evolving meaning”).
  113. ↑ Marco Roscini, Cyber Operations and the Use of Force in International Law (Oxford University Press 2014) 46-47. See the national positions of Australia, Germany, France, the Netherlands, Sweden, the United Kingdom and the United States. As highlighted by Roscini, other analytic approaches include an ‘instrument-based approach’ which focuses on the means used, and the ‘target-based approach’ which ‘argues that cyber operations reach the threshold of the use of armed force when they are conducted against national critical infrastructure’. On the latter, see for example Estonia’s national position, combining the target and the effects-based approaches in its assessment.
  114. ↑ Marco Roscini, Cyber Operations and the Use of Force in International Law (Oxford University Press 2014) 53. See also the national positions of Australia, Brazil, Estonia, Italy, Israel and the United States. Further, it has been argued that there is a minimum threshold of intensity or gravity in the use of force, for it to fall under Article 2(4) of the UN Charter. See Roscini, 53-54. See also in this regard, Tallinn Manual 2.0., commentary to rule 69, para 9(a).
  115. ↑ Marco Roscini, Cyber Operations and the Use of Force in International Law (OUP 2014) 55. See also ibid, 48 (noting that ‘the dependency of modern societies on computers, computer systems, and networks has made it possible to achieve analogous prejudicial results through other, non-destructive means’)
  116. ↑ However, such claims are occasionally made in the scholarship: see, for example, Marco Roscini, Cyber Operations and the Use of Force in International Law (OUP 2014) 59; Nicholas Tsagourias 'Cyber Attacks, Self-Defence and the Problem of Attribution' (2012) 17 (2) Journal of Conflict and Security Law 23; Gary Brown and Keira Poellet, ‘The Customary International Law of Cyberspace’ (2012) Strategic Studies Quarterly 137.
  117. ↑ Dan Efrony and Yuval Shany, ‘A Rule Book on the Shelf? Tallinn Manual 2.0 on Cyberoperations and Subsequent State Practice’ (2018) 112 AJIL 583, 638.
  118. ↑ French Ministry of the Armies, ‘International Law Applied to Operations in Cyberspace’ (9 September 2019) 7, stating that ‘France does not rule out the possibility that a cyberoperation without physical effects may also be characterised as a use of force’.
  119. ↑ Dutch Ministry of Foreign Affairs, ‘Letter to the parliament on the international legal order in cyberspace’ (5 July 2019) 4, stating that ‘in the view of the government, at this time it cannot be ruled out that a cyber operation with a very serious financial or economic impact may qualify as the use of force’.
  120. ↑ 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) 69-70, stating that ‘Likewise, a cyber operation causing severe disruption to the functioning of the State such as the use of crypto viruses or other forms of digital sabotage against governmental or private power grid- or telecommunications infrastructure, or cyber operations leading to the destruction of stockpiles of Covid-19 vaccines, could amount to the use of force in violation of Article 2(4). Similarly, the use of crypto viruses or other forms of digital sabotage against a State’s financial and banking system, or other operations that cause widespread economic effects and destabilisation, may amount to the use of force in violation of Article 2(4)’.
  121. ↑ Dutch Ministry of Foreign Affairs, ‘Letter to the parliament on the international legal order in cyberspace’ (5 July 2019) at p. 4.
  122. ↑ French Ministry of the Armies, ‘International Law Applied to Operations in Cyberspace’ (9 September 2019) 7.
  123. ↑ Tallinn Manual 2.0, commentary to rule 69, para 9. The indicative factors highlighted by the Manual are: (i) severity; (ii) immediacy; (iii) directness; (iv) invasiveness; (v) measurability of effects; (vi) military character; (vii) State involvement; and (viii) presumptive legality.
  124. ↑ Italian Ministry for Foreign Affairs and International Cooperation, ‘Italian position paper on “International law and cyberspace”’ (2021) 8. See also the national position of Israel, stating that ‘As with any legal assessment relating to the cyber domain, as practice in this field continues to evolve, there may be room to further examine whether operations not causing physical damage could also amount to use of force’.
  125. ↑ See Articles 39–42 of the UN Charter.
  126. ↑ See Article 51 of the UN Charter.
  127. ↑ See in this regard the national positions of Australia, the Netherlands and Romania.
  128. ↑ Cf. US, State Department Legal Advisor Brian Egan, International Law and Stability in Cyberspace, Speech at Berkeley Law School (10 November 2016), 13 (“In certain circumstances, one State’s non-consensual cyber operation in another State’s territory could violate international law, even if it falls below the threshold of a use of force.”) (emphasis original); UK, Attorney General Jeremy Wright QC MP, Cyber and International Law in the 21st Century, Speech (23 May 2018) (“In certain circumstances, cyber operations which do not meet the threshold of the use of force but are undertaken by one state against the territory of another state without that state’s consent will be considered a breach of international law.”); Government of the Kingdom of the Netherlands, Appendix: International law in cyberspace (26 September 2019) 4; 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) 77.
  129. ↑ Tallinn Manual 2.0, commentary to Rule 69, para 9.
  130. ↑ ILC Articles on State Responsibility, Commentary, part 3 ch 2 at para 1.
  131. ↑ Australian Government, Australia's position on how international law applies to State conduct in cyberspace (2020).
  132. ↑ 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).
  133. ↑ Government of Canada, International Law applicable in cyberspace (April 2022) para 34.
  134. ↑ 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”
  135. ↑ 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.’
  136. ↑ 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.’
  137. ↑ Italian Ministry for Foreign Affairs and International Cooperation, 'Italian position paper on "International law and cyberspace"' (2021) 7-8.
  138. ↑ 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.’
  139. ↑ Dutch Ministry of Foreign Affairs, ‘Letter to the parliament on the international legal order in cyberspace’ (5 July 2019) 7.
  140. ↑ New Zealand Foreign Affairs and Trade, The Application of International Law to State Activity in Cyberspace (1 December 2020) 3-4.
  141. ↑ 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.
  142. ↑ 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.
  143. ↑ Government Offices of Sweden, Position Paper on the Application of International Law in Cyberspace (July 2022) 6.
  144. ↑ 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.’
  145. ↑ 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.
  146. ↑ 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.’
  147. ↑ 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.’
  148. ↑ 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).
  149. ↑ ILC Articles on State Responsibility, Art 49 para 1; Case Concerning the Gabčíkovo-Nagymaros Project (Hungary/Slovakia) (Judgment) 1997 ICJ Rep 7, para 83.
  150. ↑ 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’.
  151. ↑ 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.
  152. ↑ ILC Articles on State Responsibility, Art 52 para 1 subpara b) – Art 52 para 2.
  153. ↑ Government of Canada, International Law applicable in cyberspace (April 2022).
  154. ↑ Roy Schöndorf, Israel’s Perspective on Key Legal and Practical Issues Concerning the Application of International Law to Cyber Operations (8 December 2020).
  155. ↑ 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.
  156. ↑ 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).
  157. ↑ Hon Paul C Ney, Jr., DOD General Counsel Remarks at U.S. Cyber Command Legal Conference (2 March 2020).
  158. ↑ See also Tallinn Manual 2.0, commentary to rule 21, paras 10–12.
  159. ↑ 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.
  160. ↑ ILC Articles on State Responsibility, Art 49(3).
  161. ↑ 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].
  162. ↑ ILC Articles on State Responsibility, Art 50(1).
  163. ↑ ILC Articles on State Responsibility, Art 50(2).
  164. ↑ Articles on State Responsibility, Art 51; Case Concerning the Gabčíkovo-Nagymaros Project (Hungary/Slovakia) (Judgment) 1997 ICJ Rep 7, para 85.
  165. ↑ See ILC Articles on State Responsibility, part 3, para 5; see also Tallinn Manual 2.0, commentary to rule 23, para 7.
  166. ↑ Government of Canada, International Law applicable in cyberspace (April 2022).
  167. ↑ Federal Government of Germany, ‘On the Application of International Law in Cyberspace’, Position Paper (March 2021) 13-14.
  168. ↑ Italian Ministry for Foreign Affairs and International Cooperation, ‘Italian position paper on "International law and cyberspace"’ (2021) 7-8.
  169. ↑ 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.
  170. ↑ 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.
  171. ↑ Government Offices of Sweden, Position Paper on the Application of International Law in Cyberspace (July 2022) 6.
  172. ↑ Federal Department of Foreign Affairs, ‘Switzerland's position paper on the application of international law in cyberspace’ (May 2021) 6-7.
  173. ↑ 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).
  174. ↑ 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.
  175. ↑ ILC Articles on State Responsibility, Art 52(3).
  176. ↑ ILC Articles on State Responsibility, Art 52(4).
  177. ↑ ILC Articles on State Responsibility, Art 53.
  178. ↑ 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.
  179. ↑ 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.
  180. ↑ New Zealand Foreing Affairs and Trade, The Application of International Law to State Activity in Cyberspace (1 December 2020) 3-4.
  181. ↑ Michael Schmitt, Three International Law Rules for Responding Effectively to Hostile Cyber Operations (Just Security, 31 July 2021)
  182. ↑ 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.
  183. ↑ Government of Canada, International Law applicable in cyberspace (April 2022) para 37.
  184. ↑ ILC Articles on State Responsibility, Commentary in Part 3, Chapter 2 on Art 49, para 3.
  185. ↑ 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”).
  186. ↑ 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’”).
  187. ↑ James Green, ‘Fluctuating Evidentiary Standards for Self-Defence in the International Court of Justice’ (2009) 58 ICLQ 163, 167 (emphasis original).
  188. ↑ ILC Articles on State Responsibility, Commentary in Part 3, Chapter 2 on Art 49 para 3.
  189. ↑ ILC Articles on State Responsibility, Article 52(2).
  190. ↑ ILC Articles on State Responsibility, Article 52(1)(a) read together with Article 52(2).
  191. ↑ See also the national positions of Italy (2021) 7–8 (“The victim-State is generally required to call upon the State of origin to discontinue the wrongful act and to notify it of its intention to take countermeasures in response to wrongful cyber operations. However, in conformity with international law, this requirement may not apply if immediate action is needed to enforce the rights of the injured State and to prevent further damage.”); United States (2021) 142 (“Before an injured State can undertake countermeasures in response to a cyber-based internationally wrongful act attributable to a State, it generally must call upon the responsible State to cease its wrongful conduct, unless urgent countermeasures are necessary to preserve the injured State’s rights.”).
  192. ↑ Military and Paramilitary Activities in and against Nicaragua (Nicaragua v United States of America) (Merits) [1986] ICJ Rep 14, para 95.
  193. ↑ US Department of Defense, Office of the General Counsel, Law of War Manual (June 2015), paras. 1.11.5.2, 16.3.3.1.
  194. ↑ Military and Paramilitary Activities in and against Nicaragua (Nicaragua v United States of America) (Merits) [1986] ICJ Rep 14, para 191.
  195. ↑ Tallinn Manual 2.0, commentary to rule 71, para 8.
  196. ↑ ICRC, A Guide to the Legal Review of New Weapons, Means and Methods of Warfare: Measures to Implement Article 36 of Additional Protocol I of 1977 (Kathleen Lawand ed.) (ICRC 2006) 4.
  197. ↑ ICRC, International Humanitarian Law and the Challenges of Contemporary Armed Conflicts: Recommitting to Protection in Armed Conflict on the 70th Anniversary of the Geneva Conventions (October 2019) 34 (“In the ICRC’s view, the requirement to carry out legal review of new weapons also flows from the obligation to ensure respect for IHL under Article 1 common to the Geneva Conventions.”). This view is shared by a number of States. See, Australia, The Australian Article 36 review process, working paper submitted to the Group of Government Experts of the High Contracting Parties to the Convention on Prohibitions or Restrictions on the Use of Certain Conventional Weapons Which May be Deemed to be Excessively Injurious or to Have Indiscriminate Effects (CCW), 2018, para. 3; The Netherlands and Switzerland, Weapons review mechanisms, working paper submitted to the CCW, 2017, para. 17. See also Tallinn Manual 2.0, commentary to rule 110, para 2.
  198. ↑ Article 36 AP I.
  199. ↑ See, eg, Duncan Blake and Joseph S. Imburgia, ‘“Bloodless Weapons”? The need to conduct legal review of certain capabilities and the implications of defining them as “weapons”’, (2010) 66 AFLRev 157, 163–64; see also, William H Boothby, Weapons and the Law of Armed Conflict (2nd edn, OUP 2016) 342–43 (“For states that are not party to AP1, the implied obligation should not necessarily be expressed in the same terms as article 36, but its existence is attested to by the practice of certain states before the adoption of AP1”).
  200. ↑ See Tallinn Manual 2.0, commentary to rule 110, para 2; see also Natalia Jevglevskaja, ‘Weapons Review Obligation under Customary International Law’ (2018) 94 International Law Studies 186, 220.
  201. ↑ See, eg, US DoD Law of War Manual, para 6.2.1.
  202. ↑ David Wallace, ‘Cyber Weapon Reviews under International Humanitarian Law: A Critical Analysis’ (2018) Tallinn Paper No. 11, 9.
  203. ↑ ICRC, A Guide to the Legal Review of New Weapons, Means and Methods of Warfare: Measures to Implement Article 36 of Additional Protocol I of 1977 (Kathleen Lawand ed.) (ICRC 2006) 10.
  204. ↑ For a modern formulation of the Martens Clause, see Art 1(2) AP I (“In cases not covered by this Protocol or by other international agreements, civilians and combatants remain under the protection and authority of the principles of international law derived from established custom, from the principles of humanity and from dictates of public conscience.”). See also ICRC, A Guide to the Legal Review of New Weapons, Means and Methods of Warfare: Measures to Implement Article 36 of Additional Protocol I of 1977 (Kathleen Lawand ed.) (ICRC 2006) 17 para 1.2.2.3.
  205. ↑ David Wallace, ‘Cyber Weapon Reviews under International Humanitarian Law: A Critical Analysis’ (2018) Tallinn Paper No. 11, 9.
  206. ↑ See Tallinn Manual 2.0, commentary to rule 110, para 4. According to the majority of the International Group of Experts, it would suffice for the State to seek the advice of a legal advisor at the relevant level of command.
  207. ↑ ICRC, International Humanitarian Law and the Challenges of Contemporary Armed Conflicts: Recommitting to Protection in Armed Conflict on the 70th Anniversary of the Geneva Conventions (October 2019) 34-35; see also ICRC, A Guide to the Legal Review of New Weapons, Means and Methods of Warfare: Measures to Implement Article 36 of Additional Protocol I of 1977 (Kathleen Lawand ed.) (ICRC 2006) 11.
  208. ↑ See, eg, Gary D. Brown and Andrew O. Metcalf, ‘Easier Said Than Done: Legal Reviews of Cyber Weapons’ (2014) 7 JNSLP 115, 135 (defining a kinetic and/or a cyber weapon as “an object designed for, and developed or obtained for, the primary purpose of killing, maiming, injuring, damaging or destroying”); Tallinn Manual 2.0, rule 103, para 2 (“cyber weapons are cyber means of warfare that are used, designed, or intended to be used to cause injury to, or death of, persons or damage to, or destruction of, objects”); Air Force Instruction 51-401 (3 August 2018) 13 (defining a cyber capability as “any device, computer program or computer script, including any combination of software, firmware or hardware intended to deny, disrupt, degrade, destroy or manipulate adversarial target information, information systems, or networks”).
  209. ↑ Art 49 AP I.
  210. ↑ Tallinn Manual 2.0, rule 103, para 2; but see Jeffrey T Biller and Michael N Schmitt, ‘Classification of Cyber Capabilities and Operations as Weapons, Means, or Methods of Warfare’ (2019) 95 Int’l L Stud 179, 218 (arguing that “code used in hostile cyber operations does not qualify as a means of warfare”) and 219 (characterizing “cyber operations as a method of warfare”) (emphasis added). See further Scenario 22: Cyber methods of warfare (discussing the implications of these different views from an IHL perspective).
  211. ↑ Legality of the Threat or Use of Nuclear Weapons Case (Advisory Opinion) [1996] ICJ Rep 226, para 86.
  212. ↑ ICRC, A Guide to the Legal Review of New Weapons, Means and Methods of Warfare: Measures to Implement Article 36 of Additional Protocol I of 1977 (Kathleen Lawand ed.) (ICRC 2006) 5, 10-11, 20, and 23-24; see also Tallinn Manual 2.0, commentary to rule 110, para 6.
  213. ↑ Examples of such specific prohibitions include the general ban on the use of chemical or biological weapons.
  214. ↑ Art 23(e) Hague Regulations; Art 35(2) AP I; ICRC CIHL Study, rule 70; Tallinn Manual 2.0, rule 104. See also ICRC, A Guide to the Legal Review of New Weapons, Means and Methods of Warfare: Measures to Implement Article 36 of Additional Protocol I of 1977 (Kathleen Lawand ed.) (ICRC 2006) 15-16, paras 1.2.2.1-1.2.2.2.
  215. ↑ Art 51(4)(b) AP I; ICRC CIHL Study, rules 12 and 71; Tallinn Manual 2.0, rule 105; see also ICRC, A Guide to the Legal Review of New Weapons, Means and Methods of Warfare: Measures to Implement Article 36 of Additional Protocol I of 1977 (Kathleen Lawand ed.) (ICRC 2006) 15-16, paras 1.2.2.1-1.2.2.2; and US DoD Manual, para 16.6 (“a legal review of the acquisition or procurement of a weapon that employs cyber capabilities likely would assess whether the weapon is inherently indiscriminate”).
  216. ↑ ICRC, A Guide to the Legal Review of New Weapons, Means and Methods of Warfare: Measures to Implement Article 36 of Additional Protocol I of 1977 (Kathleen Lawand ed.) (ICRC 2006) 10.
  217. ↑ David Wallace, ‘Cyber Weapon Reviews under International Humanitarian Law: A Critical Analysis’ (2018) Tallinn Paper No. 11, 20.

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