International armed conflict

== Definition ==
International armed conflict
The law of international armed conflict (IAC) applies to any armed confrontation between two or more States,Common Article 2 GC I (stipulating that the Conventions “shall apply to all cases of declared war or of any other armed conflict which may arise between two or more of the High Contracting Parties”). even if one, several, or all of them deny the existence of an armed conflict.ICRC (ed), Commentary on the Third Geneva Convention (CUP 2021), commentary on common Article 2, para 246 (‘Even if none of the Parties recognize the existence of a state of war or of an armed conflict, humanitarian law would still apply provided that an armed conflict is in fact in existence.’). Some scholars have suggested that the fighting must be of a certain intensity before international humanitarian law (IHL) comes into effect,See, eg, Jan K Kleffner, ‘Scope of Application of Humanitarian Law’ in D Fleck (ed), The Handbook of International Humanitarian Law (3rd edn, OUP 2013) 45; ILA Use of Force Committee, Final Report on the Meaning of Armed Conflict in International Law (2010) 32; Gary D. Solis, The Law of Armed Conflict: International Humanitarian Law in War (2nd edn, CUP 2016) 162. but the prevailing view is that any “resort to armed force between States”,Prosecutor v Tadić (Decision on Jurisdiction) IT-94-1-AR72 (2 October 1995) para 70. however brief or intense, triggers the application of IHL.See, eg, Jean S. Pictet (ed) Geneva Convention IV relative to the Protection of Civilian Persons in Time of War: Commentary (ICRC 1958) 20–21; Yves Sandoz, Christophe Swinarski, and Bruno Zimmermann (eds), Commentary on the Additional Protocols of 8 June 1977 to the Geneva Conventions of 12 August 1949 (ICRC 1987) 40; René Provost, International Human Rights and Humanitarian Law (CUP 2002) 250; Jann K Kleffner, ‘Scope of Application of International Humanitarian Law’ in Dieter Fleck (ed), The Handbook of International Humanitarian Law (3rd edn, OUP 2013) 45; Andrew Clapham, ‘Concept of International Armed Conflict’ in Andrew Clapham, Paola Gaeta, and Marco Sassòli (eds), The 1949 Geneva Conventions: A Commentary (OUP 2015) 16 para 38; ICRC (ed), Commentary on the Third Geneva Convention (CUP 2021), commentary on common Article 2, para 251; Noam Zamir, Classification of Conflicts in International Humanitarian Law: The Legal Impact of Foreign Intervention in Civil Wars (Edward Elgar 2017) 53–55; Kubo Mačák, Internationalized Armed Conflicts in International Law (OUP 2018) 15–16. Furthermore, the law does not prescribe any specific form for the resort to force,Cf. Legality of the Threat or Use of Nuclear Weapons Case (Advisory Opinion) [1996] ICJ Rep 226, para 89 (holding that the relevant rules of IHL apply “to all international armed conflict, whatever type of weapons might be used”) (emphasis added). so hostilities between the belligerent States may involve any combination of kinetic and cyber operations, or cyber operations alone.Tallinn Manual 2.0, commentary to rule 82, para 11.
It is unclear what effect cyber operations unaccompanied by any use of kinetic force would have to have in order for IHL to apply. Although it seems generally accepted that if cyber operations have similar effects to classic kinetic operations and two or more States are involved, the resulting situation would qualify as an IAC,ICRC (ed), Commentary on the Third Geneva Convention (CUP 2021), commentary on common Article 2, para 288. the law is unsettled on whether cyber operations that merely disrupt the operation of military or civilian infrastructure amount to a resort to armed force for the purposes of IHL.ICRC (ed), Commentary on the Third Geneva Convention (CUP 2021), commentary on common Article 2, para 289.For State views on this matter, see, eg, Finland, ‘International law and cyberspace: Finland’s national positions’ (15 October 2020), 7 (‘International humanitarian law only applies to cyber operations when such operations are part of, or amount to, an armed conflict. Most so far known cyberattacks have not been launched in the context of an armed conflict or have met the threshold of armed conflict.’); French Ministry of the Armies, ‘International Law Applied to Operations in Cyberspace’, 9 September 2019, 12 (‘Cyberoperations that constitute hostilities between two or more States may characterise the existence of international armed conflict (IAC)’); Germany, ‘On the Application of International Law in Cyberspace: Position Paper’ (March 2021), 7 (‘An international armed conflict – a main prerequisite for the applicability of IHL in a concrete case – is characterized by armed hostilities between States. This may also encompass hostilities that are partially or totally conducted by using cyber means.’); Japan, Basic Position of the Government of Japan on International Law Applicable to Cyber Operations (28 May 2021), 7 (‘If the effects of cyber operations are taken into consideration, the conduct of cyber operations alone may reach the threshold of an "armed conflict."’).
In the cyber context, States often act through non-State intermediaries and proxies. In such situations at the outset of an armed confrontation, the relevant State must exercise a sufficient degree of control over the non-State entity that commences hostilities against another State for the situation to qualify as an IAC. However, the correct legal test to use in this regard is the subject of an ongoing controversy.See further Kubo Mačák, Internationalized Armed Conflicts in International Law (OUP 2018) 39–47. The prevailing standard for the characterization of an international armed conflict is that of “overall control”, which requires that the State provides some support and that it participates in the organization, co-ordination, or planning of the relevant operations.Prosecutor v Prlić et al (Trial Judgment) IT-04-74-T (29 May 2013), vol 1, para 86(a). A separate standard, the “effective control” test, requires that the State must exercise control over the entire course of the operations in question.See Military and Paramilitary Activities in and against Nicaragua (Nicaragua v US) (Merits) [1986] ICJ Rep 14, paras 112–15; see further Kubo Mačák, ‘Decoding Article 8 of the International Law Commission’s Articles on State Responsibility: Attribution of Cyber Operations by Non-State Actors’ (2016) 21 JCSL 405, 421. While there is still disagreement as to whether the “effective control” test is the controlling test for the purposes of attribution under the law of State responsibility, there is consensus that the “overall control” test is the correct one for conflict qualification under IHL.Case Concerning the Application of the Convention on the Prevention and Punishment of the Crime of Genocide (Bosnia and Herzegovina v Serbia and Montenegro) (Judgment) [2007] ICJ Rep 43, para 405; but see ICRC (ed), Commentary on the Third Geneva Convention (CUP 2021), commentary on common Article 2, para 304 (arguing that overall control is the controlling test in both contexts). The latter is also confirmed by decades of consistent practice by international criminal tribunals including the ICTY, the ECCC, and the ICC.See Prosecutor v Tadić (Appeal Judgment) IT-94-1-A (15 July 1999) paras 120–121; Prosecutor v Lubanga (Pre-Trial Chamber 1) ICC-01/04-01/06 (29 January 2007) paras 209–211; Case No 001/18-07-2007/ECCC/TC (26 July 2010) para 540. 
Publicly available common and national positions that address this issue include:
 (2024), (2024),
 (2023), 
 (2020), 
 (2019), 
 (2021), 
 (2023), 
 (2021).
==Common positions==
===African Union (2024)===
==National positions==
===Austria (2024)===
 
===Costa Rica (2023)===
===Finland (2020)===
===France (2019)===
===Germany (2021)===
===Ireland (2023)===
===Japan (2021)===
== Appendixes ==
=== See also ===
* Non-international armed conflict
* International humanitarian law (jus in bello)
* Scenario 13: Cyber operations as a trigger of the law of armed conflict
* Scenario 15: Cyber deception during armed conflict
* Scenario 16: Cyber attacks against ships on the high seas
* Scenario 18: Legal status of cyber operators during armed conflict
=== Notes and references ===
=== Bibliography and further reading ===
Category:International armed conflict
Category:International humanitarian law
Category:Legal concepts