Scenario 03: Cyber operation against the power grid

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[INSERT PHOTO] Intelligence services of State B compromise the supply chain of an industrial control system in State A, thereby gaining access to a part of its electric power grid. Subsequent attacks bring down the grid, leading to prolonged blackouts. The scenario considers whether such incidents may violate, among others, the prohibition of the use of force in international relations, the prohibition of intervention in the internal affairs of States, and the obligation to respect the sovereignty of other States. Specific consideration is given to the existence of a standalone obligation to refrain from attacking critical infrastructure of other States through cyber means.



Critical infrastructure, intervention, sovereignty, use of force


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 “critical national infrastructure” by the domestic law.

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 attackers who succeed in installing concealed remote-control equipment in the computers in question. Once the computers are integrated in the ICS, the attackers 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.

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.

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.

As a consequence of the operation, many households are left without electricity for days, resulting in significant inconvenience for the local residents. However, the power cuts are limited to residential areas and no physical damage or personal injury is reported from any of the affected areas.

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 designed, installed, and controlled by the intelligence services of State B. State A is a member of a collective self-defence alliance O.


  • [YEAR] Black Energy
  • [YEAR] Stuxnet
  • [YEAR] Steel mill in Germany

Legal analysis

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 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

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] However, the notion of “force” in this context is limited to armed force[4], and to operations whose scale and effects are comparable to the use of armed force.[5]

At present, the law is unsettled on the issue 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”.[6] Undoubtedly, one of the purposes of the prohibition of force under international law is to safeguard the national security of the potentially affected States.[7] 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.[8]

Admittedly, the notion of “force”, like other generic terms in treaties of unlimited duration, should be presumed to have an evolving meaning.[9] However, there is little State practice supporting the claim that its meaning has by now evolved to include non-destructive cyber operations against critical national infrastructure.[10] In fact, to date no victim State of an operation of this kind has suggested that the operation would have amounted to a use of force.[11]

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.[12] In this regard, the prohibition of non-intervention, the obligation to respect the sovereignty of other States, and the obligation to refrain from attacking other States’ critical infrastructure are all of potential relevance.

The scenario notes that the cyber operation against company X had caused significant inconvenience to many households in State A. The blackout must also have resulted in economic damage to company X and other actors on State A’s territory, likely 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, the law is unsettled in this regard and a clear conclusion cannot be made at present.

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”,[13] and even then, the permitted response is further limited by the conditions of necessity and proportionality.[14] 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.[15]

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.[16] Of course, State A would still be entitled to call upon the UN Security Council to qualify the cyber operation as having amounted to a “breach of the peace” and to decide on measures under Chapter VII of the UN Charter.[17]

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. 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

The principle of non-intervention prohibits States from intervening in the internal or external affairs of other States. Prohibited intervention was authoritatively defined by the International Court of Justice in the judgment on the merits in the 1986 case Nicaragua v United States:

A prohibited intervention must … be one bearing on matters in which each State is permitted, by the principle of State sovereignty, to decide freely. One of these is the choice of a political, economic, social and cultural system, and the formulation of foreign policy. Intervention is wrongful when it uses methods of coercion in regard to such choices, which must remain free ones.[18]

Two elements follow from this understanding. The first is that in order for an act (a term that is wide enough to include a cyber operation) to qualify as prohibited intervention, it must bear on those matters in which States are allowed to decide freely (the so-called domaine réservé of States).[19] As the ICJ ruling explains, the spectrum of such issues is particularly broad and it includes choices of political, economic, social, and cultural nature.[20]

The second element of prohibited intervention is that the act in question must be coercive in nature. There is no generally accepted definition of “coercion” in international law. However, as per the analysis in Tallinn Manual 2.0, 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)”.[21]

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”.[22] If, for instance, it transpired that State B designed the operation with the specific aim to bring to an end the ethnic discrimination by organs of State A, then this would bring it within the protected sphere of matters, fulfilling the first prong of the test.

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.[23]

Obligation to respect state sovereignty [TANA: PLEASE ADD/REFORMAT FOOTNOTES AS PER SCENARIO 101]

Sovereignty is a core principle of international law. According to a widely accepted definition in the Island of Palmas arbitral award of 1928,

[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.[2]

According to multiple declarations by the UN,[3] NATO,[4] OSCE,[5] and individual States, international law applies in cyberspace, and hence also the principle of sovereignty applies in cyberspace. It is the subject of some debate to what extent this principle operates as a standalone rule of international law.

For the proponents of this view, the prohibition on violation of sovereignty is a substantive primary rule of international law. This view is at the basis of the analysis in the Tallinn Manual[6] and it has reportedly not been challenged by any of over fifty States that had participated in the process of consultations of the Manual in 2017.[7]

By contrast, the opposing view considers that sovereignty is “a principle of international law that guides state interactions, but is not itself a binding rule”.[8] It was originally formulated by two high-level US government legal advisors writing in their private capacity[9] and it has since been endorsed at least by the UK attorney general.[10]

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 the prohibition of intervention.

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.’[11]

Each State’s sovereignty is protected by international law from violation by other States.[12]

Whether sovereignty has been violated in the present case is controversial. On the one hand, the outcome of the operation was limited to physically non-destructive effects and its impact on the electrical distribution grid was fully reversible. On the other hand, 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 balance, the better view is 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.

Possible obligation not to conduct cyber operations against other states’ critical infrastructure

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“.[24] This raises the question whether a cyber operation such as the one described in this scenario infringes an obligation not to attack critical national infrastructure of other States.

However, it is uncertain 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.[25] Of course, the frequency of 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.[26] 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.[27]

Secondly, although UN GGE reports are based on the consensus of governmental experts selected on the basis of equitable geographical representation,[28] their views cannot be said to automatically reflect customary international law. The mandate of the UN GGE is decidedly not focussed on the identification of customary legal rules; rather, it includes the proposing and promoting of “[v]oluntary, non-binding norms of responsible State behaviour”.[29] As such, the legal valence of any normative statements found in one of the reports must be understood as minimal to none.

Finally, even if the GGE did have the mandate and ability to identify relevant rules of custom, it most certainly did not do so with regard to operations against critical national infrastructure. It is manifest from the formulation cited above that the governmental experts did not consider any intentional cyber operation against critical national infrastructure to be internationally unlawful. Rather, they included the phrase “contrary to its obligations under international law”, confirming that on their view, such an operation would only violate international law if there is an additional obligation that would be breached by the operation in question.[30]

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.

Responses permitted by international law [WIP – NOT FOR INCLUSION]

The first and foremost among these are [proportionate countermeasures fulfilling the conditions as defined by international law[31]]. Although experts have agreed that cyber-attacks against critical infrastructure such as electric power grid may invoke the plea of necessity[32], the situation in State A would hardly qualify due to the lack of imminence and possibly also gravity. The consequences of the incident appear to have already been remedied by the time the attack vector was identified, there is no indication of treaty obligations of State A towards State B that the former could consider not performing, neither seem other international obligations of State A towards State B sufficiently “light” and less pressing for State A to choose not to abide by them. Further, State A has not yet publicly attributed the acts to State B and not called upon the latter for reparation.




See also

Notes and references

  1. UN Charter, Art 2(4).
  2. ICJ, Military and Paramilitary Activities in and against Nicaragua (Nicaragua v US) (Merits) [1986] ICJ Rep 14, paras 187–90; Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory (Advisory Opinion) [2004] ICJ Rep 136, para 87.
  3. See, eg, ILC Yearbook of the ILC, 1966, vol II, 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”); Gray __; Corten __; O Dörr and A Randelzhofer, ‘Article 2(4)’ in B Simma et al (eds), The Charter of the United Nations: A Commentary (3rd edn, OUP 2012) vol I, 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. O Dörr and A Randelzhofer, ‘Article 2(4)’ in B Simma et al (eds), The Charter of the United Nations: A Commentary (3rd edn, OUP 2012) vol I, 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.”).
  5. Cf. 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.”).
  6. M Roscini, Cyber Operations and the Use of Force in International Law (OUP 2014) 55.
  7. [ADD REF].
  8. Documents of the United Nations Conference on International Organization (1945), vol VI, 334.
  9. Cf. ICJ, Dispute regarding Navigational and Related Rights (Costa Rica v Nicaragua) Judgment [2009] ICJ Rep 213, para 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”).
  10. However, such claims are occasionally made in the scholarship: see, eg, M Roscini, Cyber Operations and the Use of Force in International Law (OUP 2014) 59; [ADD FURTHER REF].
  11. [ADD REF].
  12. 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.”).
  13. UN Charter, Art 51.
  14. See, eg, ICJ, Military and Paramilitary Activities in and against Nicaragua (Nicaragua v US) (Merits) [1986] ICJ Rep 14, para 194; ICJ, Legality of the Threat or Use of Nuclear Weapons Case (Advisory Opinion) [1996] ICJ Rep 226, para 41; ICJ, Oil Platforms (Iran v US) [2003] ICJ Rep 161, para 43.
  15. ICJ, 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, 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“).
  16. 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).
  17. See UN Charter, Art 39.
  18. ICJ, Military and Paramilitary Activities in and against Nicaragua (Nicaragua v US) (Merits) [1986] ICJ Rep 14, para 205.
  19. See, eg, KS Ziegler, “Domaine Réservé”, in R 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”).
  20. ICJ, Military and Paramilitary Activities in and against Nicaragua (Nicaragua v US) (Merits) [1986] ICJ Rep 14, para 205.
  21. Tallinn Manual 2.0, commentary to rule 66, para 21.
  22. Tallinn Manual 2.0, commentary to rule 66, para 11.
  23. 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”).
  24. UN GGE 2015 report, para. 13(f).
  25. 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.”).
  26. ICJ, 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.
  27. 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”).
  28. UNGA Res 68/243 (27 December 2013), preambular para 16.
  29. UN GGE 2015 report, 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.
  30. Cf. UN GGE 2015 report, para. 13(f).
  31. [ICJ in Gabčíkovo-Nagymáros]
  32. [Tallinn Manual, rule 26, para. 5: ‘Most of the Experts agreed that ... a cyber operation that would ... shut down a large electrical grid‘ would be sufficient to invoke the plea of necessity]