Threshold Criteria for Non-International Armed Conflict under IHL


The conduct of belligerent parties in an armed conflict is governed by international humanitarian law (IHL). IHL distinguishes between two types of armed conflicts: international armed conflicts (IACs) and non-international armed conflicts (NIAC).1Saul B and Akande D, The Oxford Guide to International Humanitarian Law (Oxford University Press 2020), pg 29 The International Committee of the Red Cross (ICRC) defines an IAC armed conflict between two or more states.2Geneva Conventions 1949, Common Article 2 A NIAC is defined as “protracted armed confrontations occurring between governmental armed forces and the forces of one or more armed groups, or between such groups arising on the territory of a State”.3’How Is the Term “Armed Conflict” Defined in International Humanitarian Law?’ (, 2008) <> accessed 18 July 2023

Prior to World War II, international law exclusively applied to interstate conflicts. Internal armed conflicts or civil wars were not subject to international legal regulation. IHL consisted of the Hague Conventions of 1899 and the Hague Regulations of 1907, as well as of customary rules. The first recognised distinction between IACs can be found in the Geneva Conventions.4Supra Note 1, P29

The application of the Geneva Conventions to an internal issue was contingent upon the recognition of insurgent parties exhibiting state-like characteristics.5IBID The steady expansion of international rights and obligations to individuals, as demonstrated by the postwar prosecution of international crimes, and the development of international human rights law, allowed leeway for the application of international law to armed conflicts.6IBID, P 30 According to this emerging view, international law applied to the conduct of hostilities during internal conflicts.7IBID However, due to the various manifestations of internal conflict, from mere riots and disturbances to full-scale war, it was unclear when violence occurring within a state should be classified as a NIAC, and therefore be subject to IHL.8IBID, P40 It was also unclear what set of IHL rules would apply to NIACs, after which Additional Protocol II to the Geneva Conventions, (AP-II)9Protocol Additional to the Geneva Conventions of 12 August 1949, and relating to the Protection of Victims of Non-International Armed Conflicts (Protocol II), 8 June 1977. was adopted in 1977 as a supplementary codified body of rules specifically applicable to NIACs.

This article examines the threshold criterion for a NIAC under Common Article 3 of the Geneva Conventions and as established by the International Criminal Tribunal for the former Yugoslavia (ICTY) in the landmark Tadic case.10Prosecutor v. Dusko Tadic (Appeal Judgement), IT-94-1-A, International Criminal Tribunal for the former Yugoslavia (ICTY), 15 July 1999 & Geneva Conventions of 12 August 1949 The limitations of Common Article 3 are also discussed. The discussion of Common Article 3 will be compared with a discussion of the additional threshold criteria set under Article 1(1) of AP-II along with its limitations.

Distinction between IAC and NIAC

It is important to distinguish between the main features of an IAC and a NIAC. In an IAC, the opposing sides are state armed forces, whereas in a NIAC, at least one of the opposing sides is a non-State armed group (NSAG).11Lawand K, ‘Internal Conflicts or Other Situations of Violence – What Is the Difference for Victims?’ (ICRC, 10 December 2012) <> accessed 24 June 2023 The term ‘NIAC’ refers to a situation of violence involving protracted armed confrontation on the territory of a State between government forces and one or more organised armed groups, or between such groups themselves.12IBID Thus, a NIAC can be fought between an NSAG and a State, as well as between two NSAGs. While there is a nominal threshold for triggering IAC, such as minor skirmishes or the capture of a single soldier,13Haque AA, ‘Triggers and Thresholds of Non-International Armed Conflict – Just Security’ (Just Security – A Forum on Law, Rights, and U.S. National Security, 27 August 2018) <> accessed 23 June 2023 the NIAC threshold standards are relatively higher.

Purpose of the Threshold Criteria for NIACs

The threshold criteria for NIACs seeks to maintain a balance between state sovereignty and the protection of individuals. Common Article 3 keeps the sovereignty of the state intact as it ensures the sovereign right of states to maintain or re-establish law and order.14Supra Note 1, P 41 If, on the other hand, a situation of violence arises which amounts to a NIAC, Common Article 3 and other IHL provisions applicable in NIAC ensure that the parties to that conflict are under an international legal obligation to provide certain fundamental protections to the certain groups involved in the conflict (such as sick, wounded and shipwrecked soldiers, civilians and persons hors de combat) and to comply with the rules of IHL.15‘Protocol Additional to the Geneva Conventions of 12 August 1949, and Relating to the Protection of Victims of Non-International Armed Conflicts (Protocol II), 8 June 1977. Commentary of 1987’ (IHL) <> accessed 13 July 2023 The purpose of the NIAC criterion is to hold states accountable: if states conduct crimes against humanity or war crimes, the military command of that state’s armed forces will be held accountable.16Gandhi M, ‘ISIL Year Book of International Humanitarian and Refugee Law’ (WorldLII) <> accessed 13 July 2023 Such accountability mechanisms include military tribunals, domestic judicial systems and international criminal courts and tribunals, such as the International Criminal Court or tribunals such as the ICTY.17IBID

The Threshold Criteria Under Common Article 3

Although Common Article 3 does not state any grounds for determining a NIAC, the Tadic judgement provides the most authoritative framework for determining the threshold requirements of a NIAC. Common Article 3 only applies to “armed conflict not of an international character occurring in the territory of one of the High Contracting Parties”.18Supra Note 1, pg 31 Under customary IHL, a NIAC governed under Common Article 3 may be a conflict between a state and a non-state group, or between non-state groups.19Supra Note 1, P 40 As a result, at least one party must be a non-state group.20IBID

The ICTY laid down two requirements in Tadic for a NIAC: the involvement of an organised armed group, and the intensity of violence.21Cullen A, The Concept of Non-International Armed Conflict in International Humanitarian Law (Cambridge University Press 2010) The first criterion for determining the existence of NIAC is the involvement of an organised armed group.22Supra Note 1, pg 40 According to Tadic, the NSAGs involved must possess an organised structure that can sustain and mount a coordinated military operation. The ICTY offers additional insight into the characteristics that determine whether an organised armed group is involved in hostilities. These include the ability to provide military training; the establishment of headquarters and military police; the incorporation of internal regulation and disciplinary rules among the unit; the capacity to recruit new members; the involvement of the group in political dialogues; the fabrication of arms distribution channels; and the use of uniforms and various other equipment.23Prosecutor v. Dusko Tadic (Appeal Judgement), IT-94-1-A, International Criminal Tribunal for the former Yugoslavia (ICTY), P 195 & 196, Paragraph,  561-562; Prosecutor v. Boskoski and Tarculovski (Trial Judgment), IT-04-82-T, International Criminal Tribunal for the former Yugoslavia (ICTY), 10 July 2008

The Tadic criteria was applied by the ICTY in other similar cases. In these cases, the ICTY Trial Chamber highlighted the conditions indicative of the level of organisation required for an armed group to qualify as ‘organised’ under the Tadic definition.24Supra Note 20, 124 &  10., Prosecutor v. Slobodan Milosevic (Decision on Interlocutory Appeal on Kosta Bulatovic Contempt Proceedings),  IT-02-54-A-R77.4, International Criminal Tribunal for the former Yugoslavia (ICTY), 29 August 2005, Prosecutor v. Boskoski and Tarculovski (Trial Judgment), IT-04-82-T, International Criminal Tribunal for the former Yugoslavia (ICTY), 10 July 2008 These include an organized military force with an official joint command structure, headquarters, designated zones of operation, and the ability to procure, transport, and distribute arms.25IBID, P 124 and 125 The Tadic test was also applied in the Limaj case26IBID, P 124 and 125, 11.    Prosecutor v. Limaj et al. (Trial Judgment), IT-03-66-T, International Criminal Tribunal for the former Yugoslavia (ICTY), 30 November 2005, Paragraph 171 to describe the Kosovo Liberation Army (KLA).27IBID, P 125 The KLA’s ability to recruit, train, and equip new members, as well as its possession of weaponry such as artillery mortars and rocket launchers, was cited as evidence of it being recognised as an ‘organised armed group’ for the application of Common Article 3. The Trial Chamber stressed the severity of hostilities in the use of these weapons as additional evidence of the KLA being an organised armed group.28IBID, 125, 126, 127

The second threshold criteria required for a NIAC is that violence must reach a certain degree of intensity.29Supra Note 1, pg 41 In Tadic, the ICTY termed this as “protracted armed violence”, indicating the intensity of force rather than the duration that the violence persists.30IBID, pg 41, Prosecutor v. Dusko Tadic (Appeal Judgement), IT-94-1-A, International Criminal Tribunal for the former Yugoslavia (ICTY)  Paragraph 561 For this, the ICTY relied on a variety of indicators, such as the severity and duration of an individual confrontation; the progressive nature of violence and the resulting territorial expansion; the characteristics of hostilities (i.e.  the forces involved in the hostilities); the types of arms the forces equip themselves with; the extent of casualties, displacement of people and material destruction; and the attraction of scrutiny or action by the UN Security Council.31Prosecutor v. Boskoski and Tarculovski (Trial Judgment), IT-04-82-T, International Criminal Tribunal for the former Yugoslavia (ICTY), 10 July 2008

The Tadic protracted armed violence was referred to in the Haradinaj case. The Haradinaj Trial Chamber deliberated on many factors to determine whether the intensity threshold criteria was met. Adapting the criteria in Tadic, the Haradinaj Trial Chamber’s analysis included references to the number, duration, and intensity of individual confrontations; the type of weapons and other military equipment used; the number and calibre of munitions fired; the number of persons and types of forces involved in the fighting; the number of casualties; the extent of material destruction; and the number of civilians fleeing combat zones.32IBID, pg 41, 12.                Prosecutor v. Haradinaj et al. (Trial Judgment), IT-04-84-T, International Criminal Tribunal for the former Yugoslavia (ICTY), 3 April 2008

While the ICTY’s jurisprudence on Common Article 3 is quite developed, one of the limitations of Common Article 3 is that it does not provide a definition of a NIAC. Therefore, state practice, academic scholars, and jurisprudence have been important in determining the parameters of when a NIAC can be deemed to exist.33Kkienerm, ‘Counter-Terrorism Module 6 Key Issues: Categorization of Armed Conflict’ (Counter-Terrorism Module 6 Key Issues: Categorization of Armed Conflict) <> accessed 18 July 2023 In his commentary on the Geneva Conventions, Pictet states that the armed conflict referred to in Common Article 3 relates to “armed forces on either side engaged in hostilities – conflicts, in short, which are in many ways similar to an international war, but take place within the confines of a single country”.34Jean S. PICTET, Geneva Conventions of 12 August, 1949: Commentary (Geneva,1958), p.36. In practice, low-intensity conflicts are not considered to be armed conflicts. Thus, riots or disturbances to public order are not deemed to be NIACs. Nevertheless, some experts are of the opinion that states can leverage the ambiguity surrounding the provision to further limit its applicability, even where the violence reaches levels characteristic of IACs. This can be particularly problematic where the evaluation of the existence of a NIAC is done by the state participating in the very NIAC in question. This way, the state may object to the existence of a NIAC in its territory on the grounds that it is an internal affair and the parties’ rights cannot be governed by IHL.35Supra Note 17 In its 28th International Conference of the Red Cross and Red Crescent, the ICRC stated that states may sometimes deny the applicability of IHL on the grounds that it is a situation of tension or one that involves banditry or terrorist activities that do not amount to a NIAC. If states recognise that such an armed conflict is taking place, in their view, it implicitly grants legitimacy to the armed group.36‘ICRC, IHL and the Challenges of Contemporary Armed Conflicts’ (ICRC, IHL and the Challenges of Contemporary Armed Conflicts | How does law protect in war? – Online casebook) <> accessed 20 July 2023

Threshold Criteria Under Article 1(1), AP-II

Similar to the jurisprudence that has developed under Tadic, Article 1(1) AP-II states that certain criteria must be fulfilled to determine the existence of a NIAC. The rules under AP-II apply to armed conflicts taking place on the territory of a party “between its armed forces and dissident armed forces or other organized armed groups which, under responsible command, exercise such control over a part of its territory as to enable them to carry out sustained and concerted military operations and to implement this Protocol.”37Article 1(1) AP II According to this definition, AP-II only applies to armed conflicts involving government armed forces and non-state armed groups; It does not encompass conflicts involving solely organised armed groups. Secondly, it places a requirement that territorial control must be established by NSAGs for them to be considered parties to a NIAC.38Supra Note 1, P 43

The organisation level required of NSAGs by Article 1(1) of AP-II is more advanced than that required by  Common Article 3. In the Hadžihasanović case, the Appeals Chamber of the ICTY stated that ‘It is evident that there cannot be an organized military force save on the basis of responsible command.’ There must be an appropriate degree of authority capable of establishing internal discipline; in other words, armed groups will not be considered ‘organised’ if they lack a responsible command structure for accountability purposes.39Dinstein Y, Non-International Armed Conflicts in International Law (Cambridge University Press 2014)  , P 60, Prosecutor v. Hadzihasanovic and Kubura (Appeal Judgment), IT-01-47-A, International Criminal Tribunal for the former Yugoslavia (ICTY), 22 April 2008

Furthermore, such an organised group must be engaged in sustained and concerted military operations. The term ‘sustained’ refers to operations that are kept running or maintained continuously.40Supra Note 21, P 153NSAGs must be sufficiently organised to exert sufficient control over the territory in order to implement AP-II, such as providing for the wounded and sick or treating detained prisoners humanely as required by Article 4 of AP-II.41‘Convention (III) Relative to the Treatment of Prisoners of War. Geneva, 12 August 1949. Commentary of 2020’ (IHL) <> accessed 13 July 2023

The test also adds the “intensity of violence” requirement. It certainly implies acts of violence that are continuous and established in time. The purpose of this requirement is to distinguish from acts of violence that are continuous, large scale, organized from the notion of riots and sporadic or isolated acts of violence. This criterion of duration is affirmed by international jurisprudence.42‘The Practical Guide to Humanitarian Law’ (Doctors without borders | The Practical Guide to Humanitarian Law) <> accessed 12 July 2023 The ICTR Trial Chamber in the Akayesu case suggested that operations must be continuous, which may be interpreted as placing a temporal requirement on the notion of intensity under AP-II.43The Prosecutor v. Jean-Paul Akayesu (Appeal Judgment), ICTR-96-4-A, International Criminal Tribunal for Rwanda (ICTR), 1 June 2001, Paragraph 626

The threshold criteria established under AP-II has several limitations. The restrictive nature of the definition under AP-II is evidenced by three requirements and all prerequisites have to be satisfied cumulatively. Firstly, non-state actors must exercise sufficient control over a sufficient amount of territory that allows them to carry out coordinated military operations. Secondly, AP-II is only applicable to conflicts between NSAGs and government armed forces, where at least one party must be affiliated with the state and the state must exercise responsibility for the action of its armed forces. This requirement is a significant limitation on the Protocol’s application, especially given that modern conflicts are often fought between rebel groups without the involvement of the state. Thirdly, the conflict must take place in the territory of a State that has ratified AP-II.44Naushad M, ‘ (RSIL, 10 June 2021) <> accessed 13 July 2023, International Humanitarian Law Applicable in Non-International Armed …’ ( <> accessed 13 July 2023 Article 1(1) of AP-II provides that an NSAG must be able to exercise control over a part of the State territory. It has not been specified what portion of territory should be controlled for the applicability of AP-II. Several suggestions were made while drafting of AP-II to specify that this should be “a non-negligible part of the territory” or a “substantial part of the territory,” but these were not adopted by the negotiators of AP-II at the time of its drafting.45Supra Note 38

Conflicting Application of Common Article 3 and AP-II?

Although AP-II develops and supplements Common Article 3, both legal frameworks may apply at the same time in a given NIAC. There has been a voice for the reform in NIAC law, calling for the elimination of the disparity in the application of Common Article 3 and AP II by lowering the latter’s threshold. The International Criminal Tribunal for Rwanda (ICTR) stated that ‘if an internal armed conflict meets the material conditions of APII, it then also automatically satisfies the threshold requirements of the broader Common Article 3’.46The Prosecutor v. Georges Anderson Nderubumwe Rutaganda (Judgement and Sentence), ICTR-96-3-T, International Criminal Tribunal for Rwanda (ICTR), 6 December 1999, Paragraph 575, P 221 When a NIAC crosses the second threshold, Common Article 3 continues to apply to hostilities alongside the more specific APII criteria; AP-II only develops and supplements Common Article 3.47Supra Note 38, P 56 Furthermore, Common Article 3 mentions specific categories of protected persons such as persons not taking active part in hostilities, prisoners of wars which AP-II does not mention.48Article 3, Geneva Conventions of 12 August 1949 In contrast, only Common Article 3 will apply in a conflict that lacks the distinguishing elements needed by the Protocol. In fact, Common Article 3 retains an autonomous existence, i.e. its applicability is not limited or affected by the Protocol’s material field of application.49Supra Note 40 There is no sign that states will relinquish it anytime soon.50Supra Note 38, P 56


The approach developed in the Tadic case has become the standard test for determining the threshold of a NIAC. According to ICTY jurisprudence, the two characteristics distinguishing an armed conflict from an internal disturbance are the level of organisation within armed groups and the intensity of hostilities. This approach provides for a broad interpretation of NIACs which satisfy these criteria.51Supra Note 38, P 156 and 157 On the other hand AP-II requires a higher threshold of application in comparison to Common Article 3. The threshold criteria of Common Article 3 applies independently even if the conflict does not satisfy the requirements of AP-II. However, if AP-II criteria applies then automatically Common Article 3 is also applicable. The two common threshold criteria will take precedence until states bring an amendment to resolve the ambiguity by creating a single NIAC threshold requirement.


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Aisha Ayub
Aisha Ayub holds an LLB (Hons) from the University of London and an LLM in International Law from SOAS. She is a human rights lawyer, activist and researcher.