Use of force

== Definition ==
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”.Charter of the United Nations (adopted 26 June 1945, entered into force 24 October 1945) 1 UNTS 16 (UN Charter) art. 2(4). This prohibition is reflective of customary international lawLegal 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. and it is frequently described as a peremptory norm of international law.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”). 
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.Marco Roscini, Cyber Operations and the Use of Force in International Law (Oxford University Press 2014) 44. 
As stated by the International Court of Justice, the prohibition applies to any use of force, regardless of the means employed.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. However, the notion of “force” in this context is limited to armed forceOliver 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.”)., and to operations whose scale and effects are comparable to the use of 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.”). This is also embodied in the national positions of several States, including Australia, Canada, Germany, Italy, the Netherlands, Romania and Sweden. As stressed by several States, each situation has to be analysed on a case-by-case basis.See the national positions of Canada, Germany, Italy, the Netherlands, Romania, Sweden and the United States.
Undoubtedly, one of the purposes of the prohibition of force under international law is to safeguard the national security of the potentially affected States.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). 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.Documents of the United Nations Conference on International Organization (1945), vol VI, 334. See also the national position of the Netherlands. 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”.Charter of the United Nations (adopted 26 June 1945, entered into force 24 October 1945) 1 UNTS 16 (UN Charter) preamble.
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.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”). Regarding its application to cyber operations, an “effects-based approach” has been mostly followed.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. 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”,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). 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”.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’)
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 infrastructureHowever, 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. and no victim State of an operation of this kind has suggested that the operation would have amounted to a use of force.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. However, States have begun addressing this question. In particular, France,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’. the NetherlandsDutch 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’. and NorwayOfficial 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)’. 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,Dutch Ministry of Foreign Affairs, ‘Letter to the parliament on the international legal order in cyberspace’ (5 July 2019) at p. 4. 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”.French Ministry of the Armies, ‘International Law Applied to Operations in Cyberspace’ (9 September 2019) 7. Several of these criteria are also reflected in the Tallinn Manual 2.0.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. 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.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’.
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,See Articles 39–42 of the UN Charter. conducted in the exercise of the inherent right to self-defence,See Article 51 of the UN Charter. or consented to by the territorial State.See in this regard the national positions of Australia, the Netherlands and Romania.
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.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. 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 common and national positions that address this issue include:
 (2024),
 (2024),
 (2020),
 (2024), 
 (2021),
 (2022),
 (2023),
 (2024),
 (2024),
 (2023),
 (2020),
 (2019), 
 (2021),
 (2023),
 (2020),
 (2021),
 (2021), 
 (2019),
 (2020), 
 (2021),
 (2023),
 (2022),
 (2021),
 (2022), 
 (2021), 
 (2012), 
 (2020),
 (2021).
==Common positions==
===African Union (2024)===
===European Union (2024)===
==National positions==
===Australia (2020)===
===Austria (2024)===
===Brazil (2021)===
===Canada (2022)===
===Costa Rica (2023)===
===Cuba (2024)===
===Czech Republic (2024)===
===Denmark (2023)===
===Estonia (2021)===
===Finland (2020)===
===France (2019)===
===Germany (2021)===
===Ireland (2023)===
===Israel (2020)===
===Italy (2021)===
===Japan (2021)===
===Netherlands (2019)===
===New Zealand (2020)===
===Norway (2021)===
===Pakistan (2023)===
===Poland (2022)===
===Romania (2021)===
===Sweden (2022)===
===United Kingdom (2021)===
===United States (2012)===
===United States (2020)===
===United States of America (2021)===
==Appendixes==
===See also===
*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
*Scenario 20: Cyber operations against medical facilities
*Scenario 23: Vaccine research and testing
===Notes and references===
===Bibliography and further reading===
Category:Use of force
Category:Legal concepts