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.
- Scenario 03: Cyber operation against the power grid
- Scenario 14: Ransomware campaign
- Scenario 16: Cyber attacks against ships on the high seas
- Scenario 17: Collective responses to cyber operations
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.”).