Scenario 03: Cyber operation against the power grid
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.
Critical infrastructure, prohibition of intervention, self-defence, 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 part of “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 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.
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 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.
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.
For a general overview of the structure of analysis in this section, see Note on the structure of articles.
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
|Use of force|
| This prohibition is reflective of customary international law and it is frequently described as a peremptory norm of international law. However, the notion of “force” in this context is limited to armed force, and to operations whose scale and effects are comparable to the use of armed force.
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”. Undoubtedly, one of the purposes of the prohibition of force under international law is to safeguard the national security of the potentially affected States. 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. 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”.
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.
As of 2020, 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 and no victim State of an operation of this kind has suggested that the operation would have amounted to a use of force. However, States have begun addressing this question. In particular, France and the Netherlands 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 criteria include the seriousness and reach of a given cyber operation’s consequences and its military nature, 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”. Several of these criteria are also reflected in the Tallinn Manual 2.0.
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. In this regard, the prohibition of non-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.
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, 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”, and even then, the permitted response is further limited by the conditions of necessity and proportionality. 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.
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. 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.
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
|Prohibition of intervention|
|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:|
In order for an act, including a cyber operation, to qualify as a prohibited intervention, it must fulfil the following conditions:
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”. 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 or 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.
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.
Obligation to respect the sovereignty of other States
|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,|
Multiple declarations by the UN, NATO, OSCE, the European Union, and individual States have confirmed that international law applies in cyberspace. Accordingly, so too does the principle of sovereignty. However, there is some debate as to whether this principle operates as a standalone rule of international law, the breach of which gives rise to state responsibility.
The remainder of this section proceeds on the basis of the former “sovereignty-as-rule” approach. Those espousing the latter “sovereignty-as-principle” approach should refer to other relevant sections of the legal analysis (such as that on the prohibition of intervention).
It is understood that sovereignty has both an internal and an external component. 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.”
As a general rule, each State must respect the sovereignty of other States. 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.
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:
The Tallinn Manual’s view of what constitutes a violation of sovereignty has been expressly endorsed by one State: the Netherlands. 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”.
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.
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“. 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 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. 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. 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.
Secondly, although UN GGE reports are based on the consensus of governmental experts selected on the basis of equitable geographical representation, 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”. 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.
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.
- Use of force: Did the operation result in actual physical damage or injury to individuals?
- Non-intervention: Did the operation bear on any of those matters in which States are allowed to decide freely?
- Non-intervention: 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?
- Sovereignty: Were any individuals associated with an outside State physically present in the domestic State’s territory without the latter’s consent?
- Sovereignty: Did the operation occasion a loss of functionality of cyber infrastructure?
- Sovereignty: 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?
- Prohibition of intervention
- Use of force
- Scenario 06: Cyber countermeasures against an enabling State
Notes and references
- Charter of the United Nations (adopted 26 June 1945, entered into force 24 October 1945) 1 UNTS 16 (UN Charter) art. 2(4).
- Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory (Advisory Opinion)  ICJ Rep 136, para 87; Military and Paramilitary Activities in and against Nicaragua (Nicaragua v United States of America) (Merits)  ICJ Rep 14, paras 187–190.
- 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 (Hart Pub. 2010) 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”).
- 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.”).
- 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.”).
- Marco Roscini, Cyber Operations and the Use of Force in International Law (OUP 2014) 55.
- 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).
- Documents of the United Nations Conference on International Organization (1945), vol VI, 334.
- Charter of the United Nations (adopted 26 June 1945, entered into force 24 October 1945) 1 UNTS 16 (UN Charter) preamble.
- Cf. 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”).
- 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.
- 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.
- French Ministry of the Armies, ‘International Law Applied to Operations in Cyberspace’, 9 September 2019, at p. 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’.
- Dutch Ministry of Foreign Affairs, ‘Letter to the parliament on the international legal order in cyberspace’ (5 July 2019) at p. 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’.
- Dutch Ministry of Foreign Affairs, ‘Letter to the parliament on the international legal order in cyberspace’ (5 July 2019) at p. 4.
- French Ministry of the Armies, ‘International Law Applied to Operations in Cyberspace’, 9 September 2019, at p. 7.
- Tallinn Manual 2.0, commentary to rule 69, para 9.
- 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.”).
- 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 184.108.40.206.
- See, eg, Military and Paramilitary Activities in and against Nicaragua (Nicaragua v US) (Merits)  ICJ Rep 14, para 194; Legality of the Threat or Use of Nuclear Weapons Case (Advisory Opinion)  ICJ Rep 226, para 41; Oil Platforms (Iran v US)  ICJ Rep 161, para 43.
- Military and Paramilitary Activities in and against Nicaragua (Nicaragua v US) (Merits)  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“).
- 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).
- See Charter of the United Nations (adopted 26 June 1945, entered into force 24 October 1945) 1 UNTS 16 (UN Charter) Art 39.
- Military and Paramilitary Activities in and against Nicaragua (Nicaragua v US) (Merits)  ICJ Rep 14, para 205.
- 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.
- 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”).
- Tallinn Manual 2.0, commentary to rule 66, para 19.
- 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.
- Tallinn Manual 2.0, commentary to rule 66, para 21.
- Tallinn Manual 2.0, commentary to rule 66, paras 19, 27.
- Tallinn Manual 2.0, commentary to rule 66, para 24 (The exact nature of the causal nexus was not agreed on).
- Tallinn Manual 2.0, commentary to rule 66, para 11.
- 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”).
- Island of Palmas (Neth. v. U.S.), 2 RIAA 829, 838 (Perm. Ct. Arb. 1928).
- UNGA Res 71/237 (30 December 2015) UN Doc A/RES/20/237.
- 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.
- 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.
- 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).
- Michael N Schmitt, 'Virtual Disenfranchisement: Cyber Election Meddling in the Grey Zones of International Law' (2018) 19 ChiJIntlL 30,40; Tallinn Manual 2.0, commentary to rule 4, para 2 (‘States shoulder an obligation to respect the sovereignty of other States as a matter of international law’).
- See Michael N Schmitt and Liis Vihul, ‘Respect for Sovereignty in Cyberspace’ (2017) 95 Tex L Rev. 1639, 1649 (noting that States ‘voiced no meaningful objection to Rule 4’ and that ‘it appeared to be received knowledge that a primary rule on territorial-sovereignty violations existed and applied to cyber operations.’).
- 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’.
- 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.’
- 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’.
- Norbert Riedel, ‘Cyber Security as a Dimension of Security Policy’ (18 May 2015), arguing that ‘[e]ven in cases where one cannot speak of a use of force, the use of cyber capabilities might constitute a violation of sovereignty, if the attack can be attributed to a state, which then in turn could lead to consequences within the confines of public international law’.
- 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.’).
- 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’.
- 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’).
- Jeremy Wright, ‘Cyber and International Law in the 21st Century’ (23 May 2018) (stating that he was ‘not persuaded that we can currently extrapolate from that general principle a specific rule or additional prohibition for cyber activity beyond that of a prohibited intervention. The UK Government’s position is therefore that there is no such rule as a matter of current international law’); see also Memorandum from JM O’Connor, General Counsel of the Department of Defense, ‘International Law Framework for Employing Cyber Capabilities in Military Operations’ (19 January 2017) (considering that sovereignty is not ‘a binding legal norm, proscribing cyber actions by one State that result in effects occurring on the infrastructure located in another State, or that are manifest in another State’), as cited by Sean Watts & Theodore Richard, 'Baseline Territorial Sovereignty and Cyberspace' (2018) 22 Lewis & Clark L. Rev. 771, 829.
- 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’.
- Cf. James Crawford, Brownlie's Principles of Public International Law (OUP 2012) 448.
- Tallinn Manual 2.0, rule 2.
- 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.')
- 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.
- Tallinn Manual 2.0, commentary to rule 4, para 5 and 12.
- 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)  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.
- Tallinn Manual 2.0, commentary to rule 4, para 7; commentary to rule 32, para 9.
- Tallinn Manual 2.0, commentary to rule 4, para 11.
- Tallinn Manual 2.0, commentary to rule 4, para 12.
- Tallinn Manual 2.0, commentary to rule 4, para 13.
- Tallinn Manual 2.0, commentary to rule 4, para 14.
- Tallinn Manual 2.0, commentary to rule 4, para 15.
- Tallinn Manual 2.0, commentary to rule 4, para 16.
- Tallinn Manual 2.0, commentary to rule 4, para 18.
- Dutch Ministry of Foreign Affairs, Letter to the parliament on the international legal order in cyberspace, Letter of 5 July 2019 from the Minister of Foreign Affairs to the President of the House of Representatives on the international legal order in cyberspace, p. 3.
- French Ministry of the Armies, International Law Applied to Operations in Cyberspace, p. 6.
- In favour: see, eg, Theodore Christakis, ‘The ICJ Advisory Opinion on Kosovo: Has International Law Something to Say about Secession?’ (2011) 24 LJIL 73, 84; Marcelo Kohen, ‘The Court’s Contribution to Determining the Content of Fundamental Principles of International Law’ in Giorgio Gaja and Jenny Grote Stoutenburg (eds), Enhancing the Rule of Law through the International Court of Justice (Brill 2012) 145. Against: see, eg, Tallinn Manual 2.0, commentary to rule 4, para 3.
- 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).
- 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.”).
- Military and Paramilitary Activities in and against Nicaragua (Nicaragua v US) (Merits)  ICJ Rep 14, para 207, citing ICJ, North Sea Continental Shelf Cases (Federal Republic of Germany/Denmark; Federal Republic of Germany/Netherlands)  ICJ Rep 3, para 77.
- 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”).
- UNGA Res 68/243 (27 December 2013) UN Doc A/RES/68/243, para 4.
- 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.
- 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).
Bibliography and further reading
- Jack Goldsmith, ‘How Cyber Changes the Laws of War’ (2013) 24 EJIL 129.
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