Scenario 03: Cyber operation against the power grid

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Intelligence services of a State compromise the supply chain of an industrial control system in another State, thereby gaining access to a part of its electric power grid. Subsequent operations bring down the grid, leading to prolonged blackouts. The scenario considers whether such incidents may amount to, among others, a prohibited use of force, an intervention in the internal affairs of another State, or a violation of the sovereignty of another State. Specific consideration is given to whether there exists a standalone obligation to refrain from conducting operations against critical infrastructure of other States through cyber means.

Scenario[edit | edit source]

Keywords[edit | edit source]

Critical infrastructure, prohibition of intervention, self-defence, sovereignty, use of force

Facts[edit | edit source]

[F1] Government-owned company X is responsible for the distribution of electricity across a large part of the territory of State A. Accordingly, its infrastructure has been designated as part of “critical national infrastructure” by the domestic law. Parts of the information infrastructure of company X are used to control critical operations, other parts serve to perform administrative functions unrelated to critical operations.

[F2] Delivery of computers procured as part of the modernisation of the industrial control systems (ICS) used by company X is, unbeknownst to either of the contractual parties, compromised by hackers who succeed in installing concealed remote-control equipment in the computers in question. Once the computers are integrated in the ICS, the hackers are able to remotely monitor the activities in the technical control centre and to assume control over the infrastructure of company X without the staff knowing.

[F3] In the meantime, the relationship between States A and B, frail due to a shared history and a complicated ethnic composition of State A, whom State B periodically accuses of mistreating its large ethnic minority, significantly deteriorates. At one point, the distribution of power to tens of thousands of households in State A suddenly comes to a halt.

[F4] Initially, the technical control centre staff at company X are unable to locate the source of the problem. All reports generated by the ICS suggest normal operation. The controllers are unable to fix the problem remotely and technicians have to be dispatched to individual locations to perform a manual restart and thus to gradually restore the functionality of the network. In the meantime, the government sends its emergency responders and provides generators to the most affected residents.

[F5] As a consequence of the operation, many households are left without electricity for days, resulting in significant inconvenience for the local residents as well as some economic damage to company X and other actors in State A’s territory, including the State itself. However, the power cuts are limited to residential areas and no physical damage or personal injury is reported from any of the affected areas.

[F6] Much later, the source of the vulnerability is identified and the remote-control equipment is found and removed from the ICS at company X. Forensic analysis of the removed equipment determines that it was likely designed, installed, and controlled by the intelligence services of State B. State A is a member of a collective self-defence alliance O.

Examples[edit | edit source]

Legal analysis[edit | edit source]

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

[L1] The analysis in this scenario focusses on the responsibility of State B for potential violations of international law as against State A. It assumes that the cyber operation against company X was attributable to State B. Given the facts of the scenario, this assumption is not particularly controversial. As noted, the technical investigation of the incident showed that the equipment used to compromise the grid had likely been installed by the intelligence service of State B. Pursuant to Article 4 of the ILC Articles on State Responsibility for Internationally Wrongful Acts, the conduct of any State organ, irrespective of its position within the State, its functions and its character as an organ within the central government or territorial unit, shall be considered an act of that State. Intelligence services undoubtedly form part of the executive power and their conduct is thus attributable to the relevant State under Article 4. Accordingly, the remainder of the analysis considers which specific rules of international law, if any, may have been breached by the operation in question.

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”.[1] This prohibition is reflective of customary international law[2] and it is frequently described as a peremptory norm of international law.[3]

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.[4]

As stated by the International Court of Justice, the prohibition applies to any use of force, regardless of the means employed.[5] However, the notion of “force” in this context is limited to armed force[6], and to operations whose scale and effects are comparable to the use of armed force.[7] As stressed by several States, each situation has to be analysed on a case-by-case basis.[8]

Undoubtedly, one of the purposes of the prohibition of force under international law is to safeguard the national security of the potentially affected States.[9] 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.[10] 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”.[11]

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.[12] Regarding its application to cyber operations, an “effects-based approach” has been mostly followed.[13] 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”,[14] 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”.[15]

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[16] and no victim State of an operation of this kind has suggested that the operation would have amounted to a use of force.[17] However, States have begun addressing this question. In particular, France,[18] the Netherlands[19] and Norway[20] 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,[21] 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”.[22] Several of these criteria are also reflected in the Tallinn Manual 2.0.[23] 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.[24]

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,[25] conducted in the exercise of the inherent right to self-defence,[26] or consented to by the territorial State.[27]

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.[28] 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).

[L2] The scenario notes that the cyber operation against company X had caused significant inconvenience to many households in State A as well as some economic damage to a number of actors including the State itself. However, there is no indication of actual physical damage having occurred or of any injury to individuals as a result of the operation. Therefore, the principal legal question is whether such forms of interference may be categorized as a use of force inconsistent with Article 2(4) of the UN Charter. As noted, it is currently unsettled whether such interference would amount to “use of force” under international law.

[L3] In any event, the characterization of an incident of this nature as amounting to a use of force would be of limited consequence in the present scenario. This is because even if a particular act by a State qualifies as prohibited force, the victim State and its allies may only respond in self-defence if the said act is additionally of sufficient gravity to amount to an “armed attack”,[29] and even then, the permitted response is further limited by the conditions of necessity and proportionality.[30] However, the lack of destructive effects in State A strongly militates against the qualification of the cyber operation by State B as an “armed attack” under international law.[31]

[L4] Moreover, the fact that the source of the disruption was only identified after the disruptive effects had been addressed means that at that point, it could no longer be said that a use of force in self-defence by State A or by alliance O was necessary to repel an ongoing attack by State B.[32] Of course, State A would still be entitled to call upon the UN Security Council to qualify the cyber operation as either a “threat to the peace” or a “breach of the peace” and, accordingly, to decide on measures under Chapter VII of the UN Charter.[33]

[L5] However, the spectrum of unilateral responses available to State A under international law is otherwise identical to those available in response to violations of international law other than the prohibition of force, including taking countermeasures. It is thus arguably unnecessary to conclusively determine if the cyber operation against State A did in fact cross the threshold of Article 2(4) of the UN Charter, as long as the relevant conduct breached other applicable international legal rules. This is what the remainder of the analysis turns to.

Prohibition of intervention[edit | edit source]

Prohibition of intervention
The obligation of non-intervention, a norm of customary international law,[34] 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.[35]

In order for an act, including a cyber operation,[36] to qualify as a prohibited intervention, it must fulfil the following conditions:[37]
  1. The act must bear on those matters in which States may decide freely.[38] 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”[35] or the conduct of national elections[39]), and external affairs (“formulation of foreign policy”;[35] or “recognition of states and membership of international organisations”[40])—the so-called domaine réservé of States.[41] 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:[42]
    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.[43] 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)”.[44]
    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.[45] 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.[46]
    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.[47] The element of coercion also entails the requirement of intent.[48]

    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,[49] it is less clear with respect to non-forcible forms of interference.[50] Some States support the approach that intervention may take various forms, such as economic and political coercion.[51] One example that has been reiterated in several States’ positions, including Australia,[52] Brazil,[53] Canada,[54] Germany,[55] Israel,[56] New Zealand,[57] Norway,[58] Singapore,[59] the United Kingdom[60] and the United States,[61] 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.[62]

    Both potential and actual effects are considered to be relevant when assessing the coercion element.[63]

  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.[64]

  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.[65]


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).

[L6] It is unclear whether State B’s act had a bearing on State A’s domaine réservé in the present case (the first prong of the test). State A would have to establish that “the act in question [was] designed to undermine [its] authority over the domaine réservé”.[66] If, for instance, it transpired that State B designed the operation with the specific aim to affect an aspect of State A’s foreign policy, then this would bring it within the protected sphere of matters, fulfilling the first prong of the test.

[L7] As for the element of coercion, it depends, as above, on the purpose of the operation. If it was designed to compel State A to modify its policing practice, then (whether or not this outcome was in fact achieved) the second prong of the test would have been fulfilled, too.[67]

Obligation to respect the sovereignty of other States[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.[68]

Multiple declarations by the UN,[69] the African Union,[70] the European Union,[71] NATO,[72] OSCE,[73] and individual States have confirmed that international law applies in cyberspace. Accordingly, so too does the principle of sovereignty.[74] 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.[75] It has also been adopted by several States including Austria,[76] Brazil, [77] Canada,[78] the Czech Republic,[79] Estonia,[80] Finland,[81] France,[82] Germany,[83] Iran,[84] Italy,[85] Japan,[86] the Netherlands,[87] New Zealand,[88] Norway,[89] Romania[90] and Sweden.[91]
  • 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.[92] This view has been adopted by one State, the United Kingdom,[93] and has been partially endorsed by the U.S. Department of Defense General Counsel.[94] 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.[95] 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.”[96][97] This encompasses both private and public infrastructure.[98] The external component entails that States are “free to conduct cyber activities in [their] international relations”, subject to their international law obligations.[99]

As a general rule, each State must respect the sovereignty of other States.[100]However, within the cyber realm – and particularly regarding remote cyber operations – there is still no agreement on the criteria[101] and the required threshold[102] to qualify an operation as a sovereignty violation.[103] 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.[104] Accordingly, the assessment needs to be done on a case-by-case basis.[105]

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.[106] 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.[107]
  2. Causation of physical damage or injury by remote means;[108] again, “a few” Experts took the position that this is a relevant but not a determinative factor by itself.[109]
  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);[110] 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.[111]
  4. Interference with data or services that are necessary for the exercise of "inherently governmental functions";[112] although the Experts could not conclusively define the term "inherently governmental functions", they agreed that, for example, the conduct of elections would so qualify.[113]
  5. Usurpation of "inherently governmental functions", such as exercise of law enforcement functions in another State’s territory without justification.[114]

The Tallinn Manual’s view of what constitutes a violation of sovereignty has been expressly endorsed by several States including Canada,[115] Germany[116] and the Netherlands;[117] and followed to some extent by other States, such as the Czech Republic,[118] Norway,[119] Sweden[120] and Switzerland.[121] 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”;[122]similarly, Iran has argued that “unlawful intrusion to the (public or private) cyber structures” abroad may qualify as a breach of sovereignty.[123]

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.[124]

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).

[L8] Whether sovereignty has been violated in the present case is controversial. The outcome of the operation was limited to physically non-destructive effects and its impact on the electrical distribution grid was fully reversible, and therefore whether this amounts to a violation of territorial sovereignty depends inter alia on whether one considers that a State’s right to territorial sovereignty extends to intangible layers of cyberspace.

[L9] For some, emphasis should be placed on the fact that the operation caused significant inconvenience for the population and necessitated a degree of government response in the form of provision of supplies and aid. On that basis, they would submit that operations of this kind qualify as infringing on the sovereignty of the affected State given that the need to respond deprives that State of a part of its ability to conduct its affairs freely. Also, some argue that cyber operations causing temporary, though significant loss of functionality could be characterized as violations of sovereignty.[125]

Possible obligation not to conduct cyber operations against other States’ critical infrastructure[edit | edit source]

[L10] In its 2015 report, the UN group of governmental experts agreed on a formulation that “[a] State should not conduct or knowingly support ICT activity contrary to its obligations under international law that intentionally damages critical infrastructure or otherwise impairs the use and operation of critical infrastructure to provide services to the public".[126] This raises the question whether a cyber operation such as the one described in this scenario infringes an obligation not to conduct operations against the critical national infrastructure of other States.

[L11] However, it is doubtful whether such an obligation can be said to exist in the present state of international law. Three points should be made in this regard. First of all, cyber operations against critical infrastructure have recently become a very frequent occurrence in the international practice.[127] Of course, the frequency of a particular type of conduct, even if it “amount[s] to a settled practice”, does not by itself suffice to establish a new permissive rule of customary law.[128] However, the fact that most of these instances have not been accompanied by specific condemnations by those States in a position to react to them, suggests that equally, no corresponding prohibitive rule has emerged thus far.[129]

[L12] Secondly, although UN GGE reports are based on the consensus of governmental experts selected on the basis of equitable geographical representation,[130] their views do not necessarily reflect customary international law, nor should they be seen as aiming to do so. The mandate of the 2014–15 GGE was in any case not focussed on the identification of customary legal rules; rather, it included the proposing and promoting of “[v]oluntary, non-binding norms of responsible State behaviour”.[131] Given that the experts specifically described the formulation quoted in para. L11 above as one of several “recommendations for consideration by States”,[132] it should not be understood as purporting to identify a new rule of customary international law.

[L13] Thirdly, it is manifest from the formulation itself that the governmental experts did not consider that any intentional cyber operation against critical national infrastructure would automatically be internationally unlawful. This is confirmed by the use of the word “should”, which is generally considered hortatory, as opposed to “shall” or “must”.[133] Moreover, the experts included the phrase “contrary to its obligations under international law”, confirming that on their view, an operation against critical infrastructure abroad would in any event only violate international law if it breached a separate international obligation.[134] Finally, there is no universally agreed international definition of “critical infrastructure”.[135]

[L14] In sum, the preferred view is that a standalone rule prohibiting cyber operations against critical national infrastructure has not emerged in international law thus far. As such, the incident in the scenario cannot be described as infringing this supposed obligation.

Checklist[edit | edit source]

  • Use of force:
    • Did the operation result in actual physical damage or injury to individuals?
  • Prohibition of intervention:
    • Did the operation bear on any of those matters in which States are allowed to decide freely?
    • Did the operation amount to a coercive act against the victim State?
  • Sovereignty:
    • What is the position of the client on whether sovereignty is a standalone primary rule of international law?
    • Were any individuals associated with an outside State physically present in the domestic State’s territory without the latter’s consent?
    • Did the operation occasion a loss of functionality of cyber infrastructure?
    • Did the operation interfere with or usurp inherently governmental functions of another State?
  • Critical infrastructure:
    • What is the position of the client on whether there is a standalone rule prohibiting cyber operations against critical national infrastructure?

Appendixes[edit | edit source]

See also[edit | edit source]

Notes and references[edit | edit source]

  1. Charter of the United Nations (adopted 26 June 1945, entered into force 24 October 1945) 1 UNTS 16 (UN Charter) art. 2(4).
  2. 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.
  3. 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”).
  4. Marco Roscini, Cyber Operations and the Use of Force in International Law (Oxford University Press 2014) 44.
  5. 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.
  6. 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.”).
  7. 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.
  8. See the national positions of Canada, Germany, Italy, the Netherlands, Romania, Sweden and the United States.
  9. 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).
  10. Documents of the United Nations Conference on International Organization (1945), vol VI, 334. See also the national position of the Netherlands.
  11. Charter of the United Nations (adopted 26 June 1945, entered into force 24 October 1945) 1 UNTS 16 (UN Charter) preamble.
  12. 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”).
  13. 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.
  14. 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).
  15. 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’)
  16. 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.
  17. 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.
  18. 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’.
  19. 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’.
  20. 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)’.
  21. Dutch Ministry of Foreign Affairs, ‘Letter to the parliament on the international legal order in cyberspace’ (5 July 2019) at p. 4.
  22. French Ministry of the Armies, ‘International Law Applied to Operations in Cyberspace’ (9 September 2019) 7.
  23. 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.
  24. 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’.
  25. See Articles 39–42 of the UN Charter.
  26. See Article 51 of the UN Charter.
  27. See in this regard the national positions of Australia, the Netherlands and Romania.
  28. 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.
  29. Charter of the United Nations (adopted 26 June 1945, entered into force 24 October 1945) 1 UNTS 16 (UN Charter) Art 51. A minority view should be acknowledged here, according to which the right of self-defense potentially applies against any illegal use of force, irrespective of its qualification as an “armed attack”. See, eg, US DoD, Law of War Manual (December 2016), para 1.11.5.2.
  30. See, eg, Military and Paramilitary Activities in and against Nicaragua (Nicaragua v US) (Merits) [1986] ICJ Rep 14, para 194; Legality of the Threat or Use of Nuclear Weapons Case (Advisory Opinion) [1996] ICJ Rep 226, para 41; Oil Platforms (Iran v US) [2003] ICJ Rep 161, para 43.
  31. Military and Paramilitary Activities in and against Nicaragua (Nicaragua v US) (Merits) [1986] ICJ Rep 14, para 195 (holding that an operation must be characterized by sufficient “scale and effects” in order to qualify as an “armed attack”); but see Tallinn Manual 2.0, commentary to rule 71, para 12 (noting that some experts held “the view that a cyber operation directed against a State’s critical infrastructure that causes severe, albeit not destructive, effects would qualify as an armed attack“).
  32. Cf G Nolte and A Randelzhofer, ‘Article 51’ in B Simma et al (eds), The Charter of the United Nations: A Commentary (3rd edn, OUP 2012) vol II, 1426–27, para 60 (noting that the use of force in self-defence is limited to ending the attack so that the specific impulse from which the attack emerged is no longer present); but see David Kretzmer, ‘The Inherent Right to Self-Defence and Proportionality in Jus Ad Bellum’ (2013) 24 EJIL 235, 264–66 (arguing that states that have been the victims of an armed attack may under certain conditions use force to pre-empt future attacks).
  33. See Charter of the United Nations (adopted 26 June 1945, entered into force 24 October 1945) 1 UNTS 16 (UN Charter) Art 39.
  34. The customary nature has been highlighted by several States, including Australia, Brazil, Germany, Iran, Norway, Sweden, the United Kingdom and the United States.
  35. 35.0 35.1 35.2 Military and Paramilitary Activities in and against Nicaragua (Nicaragua v US) (Merits) [1986] ICJ Rep 14 [205].
  36. 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).
  37. 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.
  38. Militarv and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America) Merits, Judgment. I.C.J. Reports 1986, 14 [241].
  39. 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.
  40. 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.
  41. 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].
  42. 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.
  43. 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.’).
  44. 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.
  45. 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.’).
  46. 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.
  47. Tallinn Manual 2.0, commentary to rule 66, para 21. See also the national positions of Canada, Germany and Norway.
  48. Tallinn Manual 2.0, commentary to rule 66, paras 19 and 27. See also the national positions of Germany, New Zealand and Sweden.
  49. 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.
  50. See Harriet Moynihan, The Application of International Law to State Cyberattacks Sovereignty and Non-Intervention (Chatham House, 2 December 2019) para 82.
  51. 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’).
  52. Australian Government, Australia's position on how international law applies to State conduct in cyberspace (2020).
  53. 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.
  54. Government of Canada, International Law applicable in cyberspace (April 2022)
  55. Federal Government of Germany, ‘On the Application of International Law in Cyberspace’, Position Paper (March 2021) 5-6.
  56. Roy Schöndorf, Israel’s Perspective on Key Legal and Practical Issues Concerning the Application of International Law to Cyber Operations (8 December 2020).
  57. New Zealand Foreign Affairs and Trade, The Application of International Law to State Activity in Cyberspace (1 December 2020) 2.
  58. 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.
  59. 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.
  60. 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.
  61. 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.
  62. See the national positions of Canada, Romania, Sweden and Switzerland.
  63. 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.
  64. Tallinn Manual 2.0, commentary to rule 66, para 24 (the exact nature of the causal nexus was not agreed on).
  65. 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’).
  66. Tallinn Manual 2.0, commentary to rule 66, para 11.
  67. Tallinn Manual 2.0, commentary to rule 66, para. 29 (“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”).
  68. Island of Palmas (Neth. v. U.S.), 2 RIAA 829, 838 (Perm. Ct. Arb. 1928).
  69. UNGA Res 71/237 (30 December 2015) UN Doc A/RES/20/237.
  70. 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).
  71. 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).
  72. 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.
  73. 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.
  74. 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).
  75. 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’).
  76. 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’.
  77. 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.
  78. Government of Canada, International Law applicable in cyberspace (April 2022) para 13.
  79. 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.’
  80. 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.
  81. 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.’
  82. 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’.
  83. 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’.
  84. 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.’).
  85. Italian Ministry for Foreign Affairs and International Cooperation, ‘Italian position paper on “International law and cyberspace”’ (2021) 4.
  86. Ministry of Foreign Affairs of Japan, ‘Basic Position of the Government of Japan on International Law Applicable to Cyber Operations’ (16 June 2021) 3.
  87. 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’.
  88. New Zealand Foreign Affairs and Trade, ‘The Application of International Law to State Activity in Cyberspace’ (1 December 2020) 2.
  89. 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.
  90. 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.
  91. Government Offices of Sweden, ‘Position Paper on the Application of International Law in Cyberspace’ (July 2022) 2.
  92. 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’).
  93. 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.
  94. 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’.
  95. Cf. James Crawford, Brownlie's Principles of Public International Law (OUP 2012) 448.
  96. Tallinn Manual 2.0, rule 2.
  97. 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.
  98. Tallinn Manual 2.0., commentary to rule 4, para 5. See also the national positions of Norway, Sweden and Switzerland.
  99. Tallinn Manual 2.0., rule 3; see also the national positions of the Czech Republic, the Netherlands and Norway.
  100. 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.
  101. 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.
  102. 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.
  103. Michael Schmitt, ‘Sovereignty, Intervention, and Autonomous Cyber Capabilities’ (2020) 96 International Law Studies 549.
  104. Tallinn Manual 2.0, commentary to rule 4, para 5 and 12.
  105. See e.g. the national position of Canada, Finland, New Zealand, Norway, Sweden and Switzerland.
  106. 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.
  107. 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.
  108. Tallinn Manual 2.0, commentary to rule 4, para 11.
  109. Tallinn Manual 2.0, commentary to rule 4, para 12.
  110. 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.
  111. Tallinn Manual 2.0, commentary to rule 4, para 14.
  112. Tallinn Manual 2.0, commentary to rule 4, para 15.
  113. 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.
  114. Tallinn Manual 2.0, commentary to rule 4, para 18.
  115. Government of Canada, International Law applicable in cyberspace (April 2022) para 13.
  116. Germany, ‘On the Application of International Law in Cyberspace: Position Paper’ (March 2021), p. 4.
  117. Dutch Ministry of Foreign Affairs, ‘Letter to the parliament on the international legal order in cyberspace’ (5 July 2019), p. 3.
  118. Richard Kadlčák, Statement of the Special Envoy for Cyberspace and Director of Cybersecurity Department of the Czech Republic (11 February 2020) 3.
  119. 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.
  120. Government Offices of Sweden, Position Paper on the Application of International Law in Cyberspace (July 2022) 2
  121. Federal Department of Foreign Affairs, ‘Switzerland's position paper on the application of international law in cyberspace’ (May 2021) 3.
  122. Ministry of Defense of France, 'International Law Applied to Operations in Cyberspace' (9 September 2019) 6.
  123. 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’).
  124. 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’).
  125. See e.g. Tallinn Manual 2.0., commentary to rule 4, para 14.
  126. UN GGE 2015 'Report of the Group of Governmental Experts on Developments in the Field of Information and Telecommunications in the Context of International Security report', UN Doc A/70/174 (22 July 2015) para 13(f). The same paragraph was included in the 2021 report. See 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) norm 13(f)
  127. See, eg, US, Director of National Intelligence James Clapper, Worldwide Threat Assessment of the US Intelligence Community (26 February 2015) (“foreign actors are reconnoitering and developing access to U.S. critical infrastructure systems, which might be quickly exploited for disruption if an adversary’s intent became hostile.”); FO Hampson and M Sulmeyer (eds), Getting Beyond Norms (CIGI 2017) 6 (“Disrupting or damaging critical infrastructures that provide services to the public has become customary practice — the new normal. In the past two years and since the GGE agreement, there have been an alarming number of harmful incidents targeting critical infrastructures around the world, ranging from power systems to telecommunications systems to transportation systems to financial systems.”).
  128. Military and Paramilitary Activities in and against Nicaragua (Nicaragua v US) (Merits) [1986] ICJ Rep 14, para 207, citing ICJ, North Sea Continental Shelf Cases (Federal Republic of Germany/Denmark; Federal Republic of Germany/Netherlands) [1969] ICJ Rep 3, para 77.
  129. Cf. also ECCC, Case No 002/19-09-2007-EEEC/ OICJ (PTC38), Decision on the Appeals Against the Co-Investigative Judges Order on Joint Criminal Enterprise (JCE) (20 May 2010), para 53 (“A wealth of State practice does not usually carry with it a presumption that opinio juris exists”).
  130. UNGA Res 68/243 (27 December 2013) UN Doc A/RES/68/243, para 4.
  131. UN GGE 2015 'Report of the Group of Governmental Experts on Developments in the Field of Information and Telecommunications in the Context of International Security report' (22 July 2015) UN Doc A/70/174, para 10. On the distinction between cyber rules and cyber norms, see K Mačák, ‘From Cyber Norms to Cyber Rules: Re-engaging States as Law-makers’ (2017) 30 LJIL 877, 877–99.
  132. UN GGE 2015 'Report of the Group of Governmental Experts on Developments in the Field of Information and Telecommunications in the Context of International Security report' (22 July 2015) UN Doc A/70/174, para 13.
  133. See, eg, Robert Rosenstock, ‘The Declaration of Principles of International Law concerning Friendly Relations: A Survey’ (1971) 65 AJIL 713, 715; Pierre-Marie Dupuy, ‘Soft Law and the International Law of the Environment’ (1991) 12 Michigan J Intl L 420, 429.
  134. Cf. UN GGE 2015 'Report of the Group of Governmental Experts on Developments in the Field of Information and Telecommunications in the Context of International Security report' (22 July 2015) UN Doc A/70/174, para. 13(f).
  135. See e.g. Germany’s National position on the obligation to respect the sovereignty of other States (‘Generally, the fact that a piece of critical infrastructure (i.e. infrastructure which plays an indispensable role in ensuring the functioning of the State and its society) or a company of special public interest in the territory of a State has been affected may indicate that a State’s territorial sovereignty has been violated. However, this cannot in and of itself constitute a violation, inter alia because uniform international definitions of the terms do not yet exist. Also, cyber operations in which infrastructures and/or companies which do not qualify as ‘critical’ or ‘of particular public interest’ are affected may likewise violate the territorial sovereignty of a State’).

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