The Classification of Conflicts in International Humanitarian Law

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The classification of armed hostilities determines whether or not International Humanitarian Law (IHL) applies, and to what extent it provides protections to different actors in an armed conflict. IHL lays down a set of rules which seek, for humanitarian reasons, to limit the effects of armed conflict.1ICRC. What is International Humanitarian Law? 2004.

Specifically, it aims to protect those who do not take part or cease to take part in hostilities during an armed conflict.2ibid. Although the overall objectives of IHL are the same regardless of the nature of a conflict, there are a number of key differences that make classification important.

How a conflict is classified determines the scope of protections under IHL, as well as the jurisdiction of the International Criminal Court (ICC) and ad hoc tribunals established by the UN Security Council. In The Prosecutor v. Tadić,3ICTY, The Prosecutor v Dusko Tadić, Appeals Chamber, Decision on the Defence Motion for Interlocutory Appeal on Jurisdiction, IT-94-1-AR72, 2 October 1995 the International Criminal Tribunal of Yugoslavia (ICTY) provided the general definition of an armed conflict as existing: “whenever there is a resort to armed force between States or protracted armed violence between governmental authorities and organized armed groups or between such groups within a State.”4Ibid 70. The classification of the use of armed force as an armed conflict imposes duties on states under IHL that would not be applicable otherwise.

The distinctive features that separate International Armed Conflicts (IACs) from non-international armed conflicts (NIACs) under IHL are the structure and status of the parties involved, the threshold of intensity required to constitute an armed conflict and the applicable norms.5Zamir, Noam. “The distinction between international and non-international armed conflicts” Classification of Conflicts in International Humanitarian Law. Cheltenham, UK: Edward Elgar Publishing, 2017. The protections afforded to civilians under both types of conflicts are the same.6Henckaerts, Jean-Marie. “Study on Customary International Humanitarian Law: A Contribution to the Understanding and Respect for the Rule of Law in Armed Conflict.” International Review of the Red Cross 87.857 (2005): 198. However, the legal protections for those who have ceased to take part in hostilities or are captured as prisoners of war (POWs) vary under IHL. IACs are governed by customary international law (CIL), the entirety of the four Geneva Conventions and rules of Additional Protocol I.7International Committee of the Red Cross (ICRC), Protocol Additional to the Geneva Conventions of 12 August 1949, and relating to the Protection of Victims of International Armed Conflicts (Protocol I), 8 June 1977, 1125 UNTS 3, available at: [accessed 15 July 2021] For NIACs, only Article 3, common to the four Geneva Conventions (“common Article 3”), its Additional Protocol II and CIL are applicable. Additionally, the provisions applicable to an armed conflict under the Rome Statute of the International Criminal Court (“Rome Statute”)8UN General Assembly, Rome Statute of the International Criminal Court (​last amended 2010), 17 July 1998. also vary by classification of a conflict. The classification of any armed conflict, therefore, has both humanitarian and legal consequences.

International Armed Conflicts

An international armed conflict is defined by common Article 2 of the Geneva Conventions of 1949 (“the Geneva Conventions”),  as ‘all cases of declared war or of any other armed conflict which may arise between two or more of the High Contracting Parties’.9International Committee of the Red Cross (ICRC),  ‘The Geneva Conventions of 12 August 1949’, 2015. Available at: Any armed conflict between two or more State Parties, therefore, has an international character under IHL. Although common Article 2 restricts this definition to conflicts between ‘High Contracting Parties’, the rules of the Geneva Conventions are universally applicable as per customary international law.10Ibid 23.

The threshold to be met for the existence of an IAC is lower in comparison to the requirements for classification of an NIAC (below). According to the ICRC Commentary to the Geneva Conventions of 2016,11ICRC, Commentary on the First Geneva Convention: Convention (I) for the Amelioration of the Condition of the Wounded and Sick in Armed Forces in the Field, 2nd edition, 2016. ‘even minor skirmishes between the armed forces, be they land, air or naval forces, would spark an international armed conflict and lead to the applicability of humanitarian law’. This can in some cases be one shot fired or one person captured (so long as the state has given instructions) for IHL to apply, while in other cases (e.g. a summary execution by a secret agent sent by his government abroad), a higher level of violence is necessary.12ICRC, Fundamentals of IHL, How does Law Protect in War,

Under the rules for IACs, persons who have a right to engage in hostilities during an armed conflict are granted the status of ‘combatants’.13de Mulinen, Frédéric, Handbook on the Law of War for Armed Forces, ICRC, 1987, 47. Upon capture, combatants are granted protections as POWs and immunity from prosecution for taking part in hostilities.14de Mulinen, Frédéric, Handbook on the Law of War for Armed Forces, ICRC, 1987, at 47.IHL also provides protection to POWs in the form of minimum conditions of detention and humane treatment while in custody of enemy forces.15

Non-international Armed Conflicts

Historically, NIACs – also referred to as ‘civil wars’ – were internal matters for states to which no international laws applied. This was changed by Common Article 3 of the Geneva Conventions and Additional Protocol II (AP II), which governs all conflicts that are ‘not of an international character’. This can take the form of armed hostilities between a State party against a non-state group on its own territory, or between two or more non-state groups.

Article 1(2) of AP II specifies that it does not apply to situations such as internal disturbances and tensions, riots, isolated and sporadic acts of violence and other acts of a similar nature.16Article 1(2), Additional Protocol II. If a situation involving armed hostilities does not meet the requirements of a NIAC, it will be subject only to national laws of the state in whose territory it is taking place and overall international human rights norms. In order to distinguish an armed conflict from less severe forms of violence or internal disturbances, Common Article 3 requires a certain threshold to be met. First, the hostilities must reach a minimum level of intensity e.g. the state party resorts to using military force, as opposed to regular police action. The ICTY has provided several indicators upon which reliance could be placed to enable a determination regarding the intensity of the fighting such as the number, duration, and intensity of armed confrontations, whether the fighting is widespread,  and the types of weapons and equipment used.17Prosecutor vs. Dusko Tadić (Appeal Judgement), IT-94-1-A, (ICTY), 15 July 1999 Second, the non-state groups must be organised to an extent that they may constitute a “party to the conflict”.18International Committee of the Red Cross (ICRC). ‘How is the Term “Armed Conflict” Defined in International Humanitarian Law?’  Opinion Paper, 2008. Organisation is determined by factors such as whether the forces follow a command structure and have the capacity to sustain military operations.19ibid. In Tadić, the ICTY stated that the level of organisation could also be assessed by the group’s ability to plan and launch coordinated military operations, their capacity to recruit, train and equip combatants and its ability to act on behalf of its members.20Prosecutor vs. Dusko Tadić (Appeal Judgement), IT-94-1-A, (ICTY), 15 July 1999

The difference in scope between Common Article 3 and the definition of a NIAC under Article 1 of Additional Protocol II is that the latter adds the requirement that the organised armed group be under a responsible command and exercise control over a territory which allows them to carry out sustained and concerted military operations. Moreover, the conflicts to which Additional Protocol II applies are between a State party and a non-state actor, whereas Common Article 3 can apply to NIACs between two groups of non-state actors within the territory of a State party to the Geneva Conventions.

A striking difference between the law on IACs and NIACs is the absence of ‘combatant’ status in the latter; there are no defined rights and obligations for those taking active part in hostilities in a NIAC.21Fleck, Dieter (ed.), The Handbook of International Humanitarian Law, 2nd edn., Oxford: Oxford University Press, 2008, at 627. There is also no special status, such as that of Prisoner of War, for those captured by the other party to the conflict. Common Article 3 and Article 5 of AP II do, however, provide that persons deprived of liberty for reasons related to the conflict must be treated humanely in all circumstances.22Additional Protocol II, Article 5. In particular, they are protected from murder, torture, as well as cruel, humiliating or degrading treatment.23Ibid Article 4. 

Classification and International Criminal Law

In cases where war crimes may have been committed, classification can have implications on the application of international criminal law. Arts. 8(2)(a) and (b) of the Rome Statute list acts of violence that constitute war crimes in IACs, whilst the less extensive Arts. 8(2)(c) and (e) apply only to violations committed in NIACs. An example of the relevance of classification to framing of criminal charges is that as rules concerning Occupation are within the ambit of IACs only; the war crime of an occupying power transferring its own civilian population into occupied territory is not applicable to NIACs.24Rome Statute, Article 8 2 (b)(viii) is not found in the corresponding list for NIACs

The disparity between the number of war crimes between IACs and NIACs under the Rome Statute has been criticised, particularly due to NIACs being more prevalent in contemporary times.25Willmott, Deidre. “Removing the Distinction between International and Non-International Armed Conflict in the Rome Statute of the International Criminal Court.” Melbourne Journal of International Law 5 (2004): 196. For example, the provisions regulating use of prohibitory weapons apply only in the context of IACs.26Rome Statute, Article 8(2)(b) The differences in the treatment of acts of violence in international criminal law has also been questioned by the Appeals Chamber in Tadić:

in the area of armed conflict the distinction between interstate wars and civil wars is losing its value as far as human beings are concerned. Why protect civilians from belligerent violence, or ban rape, torture or the wanton destruction of hospitals, churches, museums or private property, as well as proscribe weapons causing unnecessary suffering when two sovereign states are engaged in war, and yet refrain from enacting the same bans or providing the same protection when armed violence has erupted ‘only’ within the territory of a sovereign state?27Tadić, Case No IT–94–1–AR72 (2 October 1995) [97].

This perspective has been reflected in the ad hoc tribunal’s hesitant approach in classification of conflicts.28Bartels, Robert. ‘The Classification of Armed Conflicts by International Criminal Courts and Tribunals’, International Criminal Law Review 1 (aop)”, 1-74 The ICC has expressed concern regarding this approach in the Prosecutor v Lubanga,29Prosecutor v. Lubanga, Case No. ICC-01/04-01/06, Judgment Pursuant to Article 74 of the Statute (Mar. 14, 2012) stating that in spite of the questions raised by academics and in the jurisprudence of ad hoc tribunals on the usefulness of classifying conflicts, the distinction is ‘not only an established part of the international law of armed conflict, but more importantly it is enshrined in the relevant statutory provisions of the Rome Statute framework, which … must be applied’.30Lubanga Trial Judgment, para. 539. It further stated that “‘in situations where conflicts of a different nature take place on a single territory, it is necessary to consider whether the criminal acts under consideration were committed as part of an international or a non-international conflict’.31Ibid, para. 551. However, in the procedural sense, such an exercise has been considered time-consuming for the ICTY since the prosecutor must ‘provide evidence and arguments for characterising the armed conflict where the crimes alleged were said to have been perpetrated in each case’.32Bennouna, Mohamed ‘The Characterisation of the Armed Conflict in the Practice of the ICTY’ in Richard May et al (eds), Essays on ICTY Procedure and Evidence in Honour of Gabrielle Kirk McDonald (2001) 57.

As the factual circumstances of contemporary conflicts continue to make classification challenging, the policy and legal reasons for the distinction under the Rome Statute remain a subject of debate. 


The development of customary international law on IHL has largely enabled its objective to be fulfilled i.e. minimising the effects of armed conflicts. In spite of the differences in regulation of IACs and NIACs, the protections afforded to civilians apply equally in both scenarios. The significant difference exists in relation to the ‘combatant’ status under IHL, which only exists for IACs. This does not, however, leave them unprotected under the larger international legal order which guarantees human rights protections.

The classification of conflicts also impacts the prosecution of war crimes, since the criminalisation of acts under the two types of conflicts may vary. This impacts the exercise of jurisdiction by the ICC and ad hoc tribunals established by the UN Security Council, but does not make the acts legal per se and perpetrators can still be prosecuted under national laws.

The usefulness of classifying conflicts, especially in light of customary international law, has been questioned. However, the existing international legal framework under both IHL and ICL necessitates such classification. Moreover, the ICC’s views expressed in cases such as Lubanga demonstrate that classification remains a necessary part of the proceedings of an international criminal trial.



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Namra Gilani

Namra Gilani is a lawyer and researcher based in Lahore. She completed her LLM in Human Rights (University of Edinburgh) in 2018, with a focus on international law and conflict. She has experience in litigation and advocacy for a range of issues including constitutional law, human rights, gender-based violence, torture and prisoners rights. Her research interests include law of armed conflict, criminal justice, protection of refugees and climate change.