How is the term “armed conflict” defined in international humanitarian law?

1. Introduction

1.1. The notion of armed conflict

International humanitarian law (IHL) applies to situations of armed conflict, a de facto state of hostilities dependent on neither a declaration nor recognition of the existence of “war” by its parties. In terms of its material scope, whether an armed conflict is an international armed conflict (IAC) or non-international armed conflict (NIAC) will largely determine which rules of IHL apply. Articles 2 and 3 common to the Geneva Conventions differentiate between the rules applicable to IACs and NIACs. However, the term “armed conflict” is defined in neither article. Far from being an oversight, the omission plays an important role in depoliticizing the application of the Conventions to the situations of violence for which they were conceived. Having learned from earlier reliance on notions such as “declarations of war”, the drafters’ choice of the notion of “armed conflict” ensured that the Conventions’ catalyst would never become a vestige of its time, but rather a concept meant to endure and, indeed, adapt in response to the changing environments for which the Conventions are needed.¹ The application of IHL has since been predicated on a fact-based analysis rather than only the formal recognition by a belligerent that a state of war exists.²

There is no central authority under international law to classify a situation as an armed conflict; parties to a conflict need to determine the legal framework applicable to the conduct of their military operations. For its part, the International Committee of the Red Cross (ICRC) makes an independent determination of the facts and systematically classifies situations for the purposes of its work. There are several reasons why the ICRC classifies conflicts. First, the High Contracting Parties to the 1949 Geneva Conventions have entrusted the ICRC, through the Statutes of the International Red Cross and Red Crescent Movement, “to work for the understanding and dissemination of knowledge of international humanitarian law applicable in armed conflicts and to prepare any development thereof”.³ Second, a fundamental part of the ICRC's mandate is to support parties to comply with their legal obligations in situations of armed conflict.⁴ Thus, interpreting the notion of “armed conflict” with a view to determining the applicable legal framework is also important from an operational lens. Third, the existence of an armed conflict  –  whether international or non-international  –  is itself an important basis for the ICRC's mandate. For example, in IACs, the ICRC has the right to visit prisoners of war (PoWs) and civilian internees. The Geneva Conventions also give the ICRC a broad right of initiative during NIACs. For these reasons, in the event of an armed conflict, the ICRC generally informs all parties to the conflict of its legal classification. The ICRC generally also informs third parties of its classification and makes the classification known publicly. Depending on the situation, the ICRC may exceptionally choose not to inform the parties to the conflict, third parties or the general public of its position regarding the applicable law.

In a 2008 opinion paper,⁵ the ICRC publicly presented the prevailing legal opinion on the definition of IAC and NIAC under IHL. The opinion paper shared insights into not just how the ICRC classifies conflicts, but also how the notion of armed conflict had been interpreted in both jurisprudence and doctrine over the nearly sixty years since the drafting of the Geneva Conventions. In the fifteen years since that publication, new challenges have arisen. The ICRC has noted several transformations in how armed groups participate in conflicts, either as parties or as supporters. Examples of such transformations include the support provided by coalitions of States to governments involved in NIACs, the non-consensual use of force by States in foreign territory, the emergence of coalitions of armed groups with fluctuating levels of organization, and the proliferation or agglomeration of such groups.

Since 2008, the ICRC has also published new Commentaries to the First, Second and Third Geneva Conventions, including Commentaries on common Articles 2 and 3,⁶ as well as reports on IHL and the challenges of contemporary armed conflicts published in the context of the International Conferences of the Red Cross and Red Crescent, which present several issues related to classification and identify developments in the law.⁷ This paper seeks to give an overview of the main features of the legal classification of contemporary armed conflicts, and it aims to make the ICRC's methodology for classification accessible and transparent for all interested in the subject.

1.2. Implication of conflict classification and declassification

Strictly speaking, IHL does not only apply during armed conflicts. Thus, the classification of an armed conflict does not signal, strictu sensu, the beginning of the application of IHL. The Geneva Conventions’ very first article requires States to “respect and to ensure respect for the [Conventions] in all circumstances”.⁸ Furthermore, nearly the entire gamut of treaties limiting or prohibiting the use of certain weapons, also considered part of IHL, include obligations for States that are party to them that apply at all times regardless of the existence of a conflict, such as the prohibitions on stockpiling anti-personnel mines, cluster munitions, biological weapons and chemical weapons, as well as obligations related to the sale and transfer of conventional weapons.

In the aftermath of an armed conflict, parties also retain several IHL obligations. Thus, the declassification of an armed conflict also does not signal, strictu sensu, the end of the application of IHL. For example, after the end of an IAC, parties retain all their obligations related to the treatment of protected persons in their power, including PoWs and civilian internees, who remain protected by the respective Convention until either their final release and repatriation (for PoWs), or release, repatriation or re-establishment (for civilian internees). In NIACs, persons protected under common Article 3, paragraph 2, continue “to benefit from the article's protection as long as, in consequence of the armed conflict, they are in a situation for which common Article 3 provides protection”, or until other legal frameworks provide a more favourable protection to them.⁹ In some instances, the end of hostilities signals the start of the application of certain rules of IHL. For example, Article 6(5) of Additional Protocol II (AP II), dealing with amnesties, and some IHL obligations relating to the clearance of certain weapons and remnants of war apply after the end of an armed conflict. Also under AP II, persons deprived of their liberty or whose liberty is restricted after the conflict for reasons related to that conflict benefit from key protections of the Protocol.¹⁰

The classification of an armed conflict also does not, in any circumstance whatsoever, legitimize, condone or legalize the resort to force by any of the parties to a conflict, nor does it necessarily reprehend or prohibit that resort to force. The legality of the resort to armed force between States is regulated by jus ad bellum, a separate body of law drawing its rules largely from the 1945 Charter of the United Nations (UN).¹¹ Therefore, the actual or perceived legitimacy of the resort to force as well as its lawfulness or unlawfulness under the UN Charter will have no effect on the applicability of IHL to a specific situation. The reason for this firm distinction between the two bodies of law is that the aims of jus ad bellum and IHL are profoundly different: the former was conceived to ensure, as far as possible, international peace and security between States. The latter is designed to protect victims of armed conflicts with no regard to who started the fighting or why fighting takes place. The applicability of IHL can thus be contingent only on the factual criteria discussed in this paper, rather than jus ad bellum considerations.

Similarly, a party's motivation in resorting to force is also irrelevant for conflict classification and its related IHL applicability.¹² This is important to recall in situations where one or both parties deny the existence of a conflict because they view the opposing party as illegitimate. Legitimacy  –  legal, political or otherwise  –  is not a relevant criterion; only the factual criteria discussed in this paper are dispositive for conflict classification. Once classified, a conflict neither legitimizes nor delegitimizes parties to conflicts.¹³ Correspondingly, the application of IHL does not affect the legal status of the parties to a conflict.¹⁴

2. International armed conflicts

2.1. The beginning of an IAC

Aside from a narrow exception discussed below,¹⁵ IACs are only those armed conflicts in which two or more States or other entities with international legal personality (including international organizations such as the UN or inter-State military alliances)¹⁶ are opposed. Common Article 2 states 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 the state of war is not recognized by one of them”.¹⁷ The terms “High Contracting Party” and “armed conflict” are not further defined in the Conventions. The former refers to the States that are party to the Conventions. Today, however, the Geneva Conventions are universally ratified by all States of the world; thus, “High Contracting Party” can be used interchangeably with “State” in reference to the Geneva Conventions. Regarding the latter term, in its seminal Tadić decision, the International Criminal Tribunal for the former Yugoslavia (ICTY) defined “armed conflict” in the context of an IAC as a resort to armed force between States.¹⁸ This definition has since been adopted by both national and other international bodies and is considered customary international law. Accordingly, as stated in the ICRC's 1952 Commentary on Geneva Convention I (GC I),

any difference arising between two States and leading to [a resort to armed force] is an armed conflict within the meaning of [Article 2 common to the Geneva Conventions] …. It makes no difference how long the conflict lasts, how much slaughter takes place, or how numerous are the participating forces.¹⁹

This is true regardless of the organ within that State that has resorted to force. Of course, only acts attributable to a State can trigger an IAC; acts by private persons not acting on behalf of a State do not trigger an IAC.²⁰ An IAC can, however, be triggered on the basis of a unilateral attack, including attacks directed towards the territory, population or infrastructure of a State. Thus, the reference to “between” in Tadić is understood broadly in terms of the existence of a belligerent relationship between parties; indeed, even a unilateral use of force is between an attacker and a recipient of that force, and so “between” does not only refer to reciprocal uses of force among two or more parties.

In contradistinction to the higher intensity threshold discussed below for NIACs, there is no specific level of intensity required for IACs.²¹ Even minor skirmishes between armed forces  –  be they land, air or naval forces²²  –  may spark an IAC and lead to the applicability of IHL.²³ There are of course other acts that, while potentially having a link to a conflict, do not meet this threshold; neither the sale nor the donation of military equipment to a party to a conflict triggers an IAC. However, once a State starts using force against another, it is both logical and in conformity with the humanitarian purpose of the Geneva Conventions that there be no requirement of a high intensity of violence to trigger an IAC.²⁴ The force used does, however, need to be a hostile act; that is, not the result of a mistake or of an individual acting ultra vires. Accidental “friendly fire” between co-belligerents does not, for example, trigger an IAC between them. Therefore, when a situation objectively shows that, for example, a State is involved as a matter of fact in military operations or any other hostile actions against another State (by neutralizing enemy military personnel or assets, hampering its military operations, or using or controlling its territory without its consent), the situation is an IAC.

2.2. IAC between a State and a non-State party: War of national liberation

The only situation in which an IAC may be classified outside of inter-State armed conflicts is a situation of organized armed violence taking place between a party to Additional Protocol I (AP I) and a people fighting against colonial domination, alien occupation or racist regimes in the exercise of their right to self-determination (i.e., a war of national liberation). Article 1(4) of AP I extends the definition of IAC to include such wars of national liberation; however, IHL applicable to IACs will only apply when, in accordance with Article 96(3) of AP I, the “authority representing a people” in this type of conflict makes a “unilateral declaration addressed to the depositary” of AP I.²⁵

2.3. The end of an IAC

Just as the start of an IAC is determined on a fact-based analysis, so too is the end of an IAC. As noted above, this requires a factual assessment in every case. Peace treaties do not always indicate the end or even the suspension of hostilities. Conversely, IACs are sometimes characterized by unstable ceasefires, a progressive decrease in intensity, and/or intervention by peacekeepers, blurring the line between the suspension and definitive end of hostilities, and rendering it more difficult to determine with precision when an IAC has ceased to exist from a legal perspective.²⁶ Thus, as is the case with the classification of conflicts, the declassification of conflicts must be based on the facts on the ground analyzed in light of the applicable IHL legal criterion, which for the ICRC is the general close of military operations. Hostilities must end with a degree of stability and permanence for the IAC to be considered terminated. A general close of military operations means not only the end of active hostilities, but also the end of “military movements of a bellicose nature, including those that reform, reorganize or reconstitute, so that the likelihood of the resumption of hostilities can reasonably be discarded”.²⁷

2.4. The beginning and end of an occupation

In some cases, an IAC may take the form of an occupation. Common Article 2 stipulates the application of the Conventions to cases of partial or total occupations (regardless of whether the occupation is met with armed resistance), though the article does not define the concept. The definition of occupation is found, however, in Article 42 of the Hague Regulations, annexed to Hague Convention IV of 1907.²⁸ The definition in this provision is the standard for determining the existence of an occupation under IHL.²⁹ According to the Hague Regulations, “[t]erritory is considered occupied when it is actually placed under the authority of the hostile army. The occupation extends only to the territory where such authority has been established and can be exercised.”³⁰ The term “authority” is not further defined in the Hague Regulations. Therefore, in order to qualify the meaning of “authority” (and thereby identify the constitutive elements of occupation), the concept of “effective control” must be considered. The phrase “effective control”, while long associated with the notion of occupation, is found in neither the Geneva Conventions nor the Hague Regulations. Rather, it developed over time in the legal discourse to describe the circumstances and conditions for determining the existence of a state of occupation. An examination of IHL treaties and their preparatory work, scholarly literature, military manuals and judicial decisions supports a three-part test for effective control with the following constitutive elements of an occupation:

1. 1. the armed forces of a State are physically present in a foreign territory or parts thereof without the consent of the effective local government in place at the time of the invasion;

2. 2. the effective local government in place at the time of the invasion has been or can be rendered substantially or completely incapable of exerting its powers by virtue of the foreign forces’ unconsented-to presence;

3. 3. the foreign forces are in a position to exercise authority over the territory concerned (or parts thereof) in lieu of the local government.

All together, these elements constitute the so-called “effective control test” used to determine whether a situation qualifies as an occupation for the purposes of IHL. As this test is cumulative (that is, each of the three elements is a necessary condition, and not an indicator, of an occupation), an occupation is considered ended for the purposes of IHL when any one of the three conditions has ceased to exist.³¹

2.5. Selected issues related to the classification of an IAC

2.5.1. Consent

As noted above, any unconsented-to use of force by one State on the territory of another State or against a State's sovereignty is an IAC. This includes situations where a State attacks individuals or groups within the territory of another State without the territorial State's consent. In some cases, a State may consent to or even call for such an intervention on its territory, for instance to respond to a threat emanating from a group fighting the government or operating against other States from within its borders. As long as the use of force remains within the limits established by the territorial State and the consent is not withdrawn, these cases would not be classified as IACs, owing to the existence of the territorial State's consent to the use of force on its territory, and therefore the lack of a belligerent relationship between it and the attacking State. If a State directs violence within another State's territory without the latter's consent  –  even if the former claims that force is not used against the government or the territorial State's infrastructure, but rather only against another party it is fighting within the framework of another armed conflict  –  this will still constitute an unconsented-to use of force against the territorial State's sovereignty and would constitute an IAC.³²

2.5.2. The classification of an IAC by proxy

As discussed in Part 3, below, sufficiently intense violence taking place between non-State armed groups (NSAGs) and States is classified as a NIAC. However, when one State exercises overall control over an NSAG fighting against another State, the conflict is classified as an IAC between the two States.³³ An NSAG is under the overall control of a State when that State is “not only … equipping and financing the group, but also … coordinating or helping in the general planning of its military activity”.³⁴ An NSAG under the overall control of a State is subordinated to that State as its de facto organ, and members of the group become the equivalent of agents of the State. As a result, fighting between the group and an opposing State does not give rise to a NIAC. Rather, the situation is classified as an IAC between the State exercising overall control over the NSAG and the State fighting that NSAG.

Similarly, a State is an Occupying Power when it exercises overall control over de facto local authorities or other local organized groups that are themselves in effective control of all or part of a territory of another State. Such an occupation by proxy would be examined using an adaptation of the effective control test for occupation by considering whether the test's conditions are met by agents controlled by that State or acting on its behalf.³⁵

2.5.3. The identification of parties in conflicts involving multinational forces

International organizations, as stated above, may become party to an IAC or a NIAC. The question then arises of who the parties to the conflict are: the individual member States that contribute their troops to that force (troop-contributing countries, TCCs), the organization itself, or both the organization and some or all of the TCCs. Answering this question requires determining to whom the sum of the multinational force's actions are attributable. IHL is silent on the issue of attribution. In the absence of specific criteria in IHL, one must rely on the general rules of public international law for determining under which conditions multinational forces’ actions can be attributed to international organizations and/or the TCCs. Acts are attributable to either a State or an international organization when that entity has control over the acts undertaken by the forces, generally corresponding to the command-and-control structure of the forces. Therefore, in the presence of a multinational force, the dispositive question to answer is which entity or entities have command and control over the military operations. In some cases, command and control is largely transferred  –  albeit never fully  –  by the TCC to the organization; in that case, only the latter should be considered party to the conflict. In other cases, the TCCs retain enough command and control such that only they would individually be considered parties to the conflict. In still other cases, the facts may indicate that both the international organization and some or all of the TCCs may simultaneously be parties to the armed conflict, owing to the level of command and control over the military operations maintained by both those TCCs and the organization.

3. Non-international armed conflicts (NIACs)

3.1. The beginning of a NIAC

Without delving into the article's historical background,³⁶ it remains important to highlight the fundamental character of Article 3 common to the Geneva Conventions, the provisions of which, while being far less extensive than the provisions for IACs, have been recognized as a “minimum yardstick” binding in all NIACs.³⁷ Customary IHL also applies to NIACs. In some NIACs (discussed below), AP II applies as well. With the very narrow exception of wars of national liberation, discussed above, all armed conflicts where at least one party is not a State (nor a supranational organization) is a NIAC.

The preparatory works to the Geneva Conventions are rich with discussions on how to restrain common Article 3's application to only what could be factually described as “armed conflict”.³⁸ Several delegates³⁹ sought to exclude the application of common Article 3 to situations of internal disturbances, banditry or other situations of violence. In its 1995 Tadić decision, the ICTY determined that a NIAC occurs “whenever there is … protracted armed violence between governmental authorities and organized armed groups or between such groups within a State”.⁴⁰ As a result of this decision and subsequent jurisprudence, it is widely accepted today that two key conditions must be met for a situation of violence to be considered a NIAC and therefore subject to IHL: the non-State party/parties must be organized, and the violence between the parties must be sufficiently intense.⁴¹ The existence of a NIAC is not predicated on any other threshold or condition. In particular, as noted above, political or other motivations of the parties play no role in the classification of a conflict.

3.1.1. Organization

Common Article 3 and subsequent rules of IHL applicable in NIAC are a noteworthy novelty of international law, in that they are binding on “parties” to a conflict rather than only States. The parties’ obligation to require compliance with IHL among their members necessitates a certain degree of organization. Correspondingly, as the ICRC has established elsewhere, a non-State party to a conflict must “possess organized armed forces. This means for example that these forces have to be under a certain command structure and have the capacity to sustain military operations.”⁴² In Tadić ⁴³ and subsequent jurisprudence,⁴⁴ the ICTY identified the threshold of organization as a requirement for the classification of a NIAC and produced a list of indicators of an armed group's organization. Indicators of organization include, inter alia:

• • the existence of a command structure and disciplinary rules;

• • the existence of a headquarters;

• • the fact that the group controls a certain territory;

• • the ability of the group to gain access to weapons or other military equipment, recruits and military training;

• • the group's ability to establish a unified military strategy and use military tactics;

• • the group's ability to plan, coordinate and carry out military operations, including troop movements and logistics; and

• • the group's ability to speak with one voice and negotiate and conclude agreements such as ceasefires or peace accords.

The identification of an armed group as sufficiently organized for the purpose of IHL classification thus does not require the fulfilment of all indicative factors, nor of any one in particular. Judicial practice does not prioritize any of them, yielding rather to a case-by-case analysis based on a contextual examination of the totality of the circumstances.

3.1.2. Intensity

Ultimately, while the States party to the Geneva Conventions decided not to define the notion of “armed conflict”, the discussion on the concept's thresholds served as an important tool to delineate the second necessary condition for the beginning of a NIAC: sufficient intensity. Once potential parties to a conflict (including NSAGs) are identified, indicators of intensity include, inter alia:

• • the number, duration and intensity of individual confrontations between them;

• • the type of weapons and other military equipment used;

• • the number and calibre of munitions fired;

• • the number of persons and types of forces partaking in the fighting;

• • the number of casualties (including, inter alia, all persons killed, wounded, displaced or missing);

• • the extent of material destruction;

• • the number of civilians fleeing combat zones; and

• • the involvement of the UN Security Council, which may also be a reflection of the intensity of a conflict.⁴⁵

A meaningful analysis of both intensity and organization can be challenging as, owing to the nature of armed conflict and the fog of war, it is often difficult to collect sufficient data on several of their indicators. However, given that the manifestation of some indicators can in turn imply the existence of others not yet empirically confirmed, it may be possible to draw some conclusions on organization based on the findings normally only relevant to intensity, and vice versa. For example, when information on a group's command-and-control structure or military equipment is unavailable, the number, duration and intensity of individual confrontations between armed groups (an indicator of intensity) may suggest that one or both sides are able to mount coordinated military operations and gain access to weapons or other military equipment, recruits and military training (an indicator of organization). This approach invokes the permeability between certain indicators of organization and intensity; it does not, however, replace either as a necessary condition for the classification of a NIAC.

A NIAC begins only when the threshold of intensity between the parties is reached. As with IACs, the notion of armed violence “between the parties” in NIACs includes unilateral uses of force. Armed violence is thus considered part of an analysis on intensity even if it is not responded to by an opposing party, as long as the opposing party meets the criterion of organization.

Strictly speaking, there is no minimum specific duration required for the classification of a NIAC, so hostilities of only a brief period may still reach the intensity threshold if, in a particular case, there are other indicators to justify such an assessment.⁴⁶ However, as the magnitude of most indicators of intensity is also expressed over time, the duration of hostilities cannot be overlooked and is considered to be an element in the assessment of intensity. It is therefore extremely unlikely that a single use of force will meet the intensity threshold required for the classification of a NIAC.

3.1.3. The applicability of Additional Protocol II

AP II develops and supplements the IHL rules applicable during certain NIACs with a more robust legal framework. While common Article 3 establishes basic humanitarian protections applicable in all NIACs, AP II is designed to provide further protection to victims in only a subset of NIACs, as established by its material scope of application. Article 1 of AP II states, in part, that it applies to NIACs taking place

in the territory of a High Contracting 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 [the] Protocol.

From this, the following five conditions can be obtained for the identification of a NIAC to which AP II applies:

1. 1. A NIAC under the classical conditions of organization and intensity exists.

2. 2. The NIAC is taking place in the territory of a party to AP II.

3. 3. The NIAC is taking place between the territorial State's armed forces “and dissident armed forces or other [NSAGs]”.

4. 4. The non-State party is under responsible command.

5. 5. The non-State party exercises “such control over a part of its territory as to enable [it] to carry out sustained and concerted military operations and to implement [AP II]”.⁴⁷

While the first three conditions are relatively straightforward, the fourth and fifth can be further clarified. “Responsible command” indicates a certain organized structure within the NSAG, even if it does not have a hierarchical military organization similar to those of regular armed forces. Such a responsible command structure needs to be able both to impose discipline among the group members and to plan and carry out military operations. A responsible command permits, in turn, the criteria listed in the fifth condition to be fulfilled. Indeed, given that AP II contains several obligations that go beyond the basic humanitarian protections of common Article 3, the additional criteria required for the Protocol's application offer “a degree of realism” corresponding to the “actual circumstances in which the parties may reasonably be expected to apply the rules developed in the Protocol, since they have the minimum infrastructure required therefor”.⁴⁸ Of course, the exact amount, type or stability of territorial control by the non-State party is not precisely set out in AP II and is context-dependent. However, the territory should elude government control. The territory's geography, terrain, size, accessibility and population may also be relevant to assessing the level of control of the non-State party.

3.2. The classification of NIACs involving coalitions

Parties to conflicts increasingly tend to fight in coalitions, often in complex relationships, which makes it necessary to identify conflict relationships and determine the applicable law. In addition to the situations described below, it is worth restating that multinational forces, as noted above, are also sometimes party to NIACs.⁴⁹ In these cases, the same analysis regarding the identification of parties, notably through an examination of the entity's command-and-control structure, is required.

3.2.1. Support-based approach

NIACs involving coalitions of multiple States, NSAGs or supranational organizations raise a question related to the threshold of intensity. Traditionally, for a situation of violence to be classified as a NIAC, the intensity of the violence between each individual State and the opposing NSAG, or between NSAGs, must reach the required intensity threshold. However, when an entity  –  a State, an NSAG or an international organization  –  supports parties to pre-existing NIACs, the supporting entity might not itself necessarily enter into such confrontations with the adversary so as to reach the threshold of violence required to constitute a separate NIAC. Rather, the supporting entity's involvement might take the form of logistical support, intelligence activities for the benefit of one party over another, or participation in the planning and coordination of military operations. These actions may effectively make the supporting entity a de facto co-belligerent while illogically allowing it to avoid responsibility for its IHL obligations and simultaneously claim protection from direct attacks. As a result, in the view of the ICRC, the classical approach expounded in Tadić must be complemented by a support-based approach to third-party operations in pre-existing NIACs. The decisive element here is the third party's direct and effective contribution to the collective conduct of hostilities by the support it provides to the State(s) involved in the pre-existing NIAC.

However, a clear distinction must be made between support that has a direct impact on the opposing party's ability to carry out its military operations and more indirect forms of support that would only allow the beneficiary to build up its military capabilities. Only the former would turn the supporting entity into a party to the armed conflict. Furthermore, it must be evident from the actions undertaken by the third party that it is pooling or marshalling military resources or coordinating actions with one of the belligerents of the pre-existing NIAC in order to fight a common enemy.

Using the support-based approach,⁵⁰ IHL applies to a State, an organized armed group or an international organization⁵¹ when:

1. 1. there is a pre-existing NIAC ongoing in the territory where an entity that is a State, an international organization or an organized armed group intervenes;

2. 2. actions related to the conduct of hostilities are undertaken by the entity in the context of that pre-existing conflict; and

3. 3. the entity's military operations are objectively carried out in support of a party to that pre-existing conflict, in particular by effectively pooling and mobilizing its military resources with that party.

For IHL to apply to a third party acting in support of one of the belligerents, all the above conditions must be fulfilled.

3.2.2. Incorporation of an armed group into a party

Conflicts can sometimes involve dozens of armed groups fighting each other in varying forms of alliances and pacts, making it difficult to identify discrete parties to these conflicts.

Sometimes, armed groups, including so-called “self-defence forces”, form part of a State's armed forces. Armed groups that are either incorporated by law as organs of the State or are empowered by law to conduct hostilities on the State's behalf are incorporated into the State's armed forces for the purposes of classification. Armed groups that are otherwise under a command responsible to a State form part of the State's irregular armed forces for the purposes of classification.

Armed groups are also considered incorporated into a party for the purposes of classification when those groups are under the command and control of a “parent” NSAG.

3.2.3. Aggregating intensity between multiple organized armed groups, State and non-State alike

In other situations when there is no pre-existing NIAC, several States, organized armed groups or international organizations may operate in a coalition where a narrow reading of Tadić would lead to legal and operational loopholes when there is a clear coordination between these entities. Such situations arise when the level of violence between each entity operating in a coalition and an opposing party (for example, the territorial State) may not meet the required intensity threshold but, taken together, the level of violence between the coalition and the opposing party does meet this threshold. In such a situation, it would be unrealistic to expect the opposing party to respond to high-intensity violence by several entities operating as a coalition only with law-enforcement measures. It is therefore submitted that, when multiple organized armed groups maintain a sufficient level of coordination in a coalition, the intensity between each of them and an opposing party may be aggregated when considering whether the threshold of intensity has been reached.⁵²

To determine a sufficient level of coordination in a coalition, a shared ideology, similarities of political views or the mere existence of a common enemy would not be sufficient. Rather, factual indicators must be considered, including, inter alia, the establishment of a coordination structure,⁵³ the sharing of operational tasks, the existence of common standard operating procedures and/or rules of engagement, the coordination of simultaneous attacks against the opposing party, and the conduct of joint military operations.

3.3. Geographical scope of IHL during NIACs

Today, many NIACs around the globe do not take the form of so-called civil wars, but they are nevertheless governed by IHL applicable to NIACs; the armed conflict test in Tadić remains broad enough to classify what are ultimately other variants of NIACs. The territorial scope of NIACs has been the subject of some debate,⁵⁴ in particular when NIACs spill over into neighbouring territory, in the case of foreign interventions, and in relation to other situations of transnational violence:

• • Spillover NIAC: NIACs sometimes spill over into the territory of a neighbouring State. In the view of the ICRC, the applicability of IHL can therefore also spill over, but only to the part(s) of the neighbouring State's territory into which the hostilities have been extended. This ensures that parties to the NIAC are not absolved of their IHL obligations by crossing an international border, while at the same time not overextending the territorial scope of IHL to the entire neighbouring country, which would not be adapted to the reality of that State.

• • Extraterritorial NIAC: An extraterritorial NIAC is a situation where States or multinational armed forces are fighting against one or more NSAGs in another host State. In such a situation, IHL applies at least in the whole territory of the host State; the law is not yet settled on whether IHL would also apply in the territory of the sending State(s), though there are cogent legal reasons to suggest that it would apply, contemporaneously with international human rights law. In the territory of the sending State(s), based on the prevailing circumstances, the rules of international human rights law will normally be the lex specialis.⁵⁵

• • Transnational situation of violence: The ICRC does not share the view that a conflict of global dimensions can take place between a State and an NSAG  –  or between NSAGs transnationally  –  for the simple reason that IHL's ratione loci in a NIAC is necessarily limited to the territory of the State in which the NIAC is actually taking place (with only the very narrow exception of a spillover NIAC, defined above). Thus, against the backdrop of the phenomenon of so-called global terrorism, the ICRC has taken the approach of classifying some situations of violence as NIACs, some as IACs (when, for example, a State has not consented to the use of force on its territory by another State, even when that force is directed against an NSAG) and some as falling outside the scope of the definition of armed conflict.⁵⁶

3.4. The end of a NIAC

As with the indicators of the start of a NIAC, common Article 3 does not provide formal requirements for determining when a conflict has come to an end. Nevertheless, for both legal and operational reasons, once a NIAC is classified, it is of course important to know when it has ended. NIACs often go through fluctuations of intensity, and temporary dips below the intensity threshold initially used to classify a conflict are not necessarily indicative of the end of a NIAC. The ICTY held in Tadić that IHL “applies from the initiation of [a NIAC] and extends beyond the cessation of hostilities until … in the case of internal conflicts, a peaceful settlement is achieved”.⁵⁷ The notion of a “peaceful settlement” is something of a misnomer, as it does not require, necessarily, a peace agreement as such. The settlement, meant here in a factual and not legal sense, need not be one accepted by or even acceptable to either or both parties. A peaceful settlement is reached when one of the two following conditions is met, either being sufficient to qualify a NIAC as having ended:

1. 1. One of the parties ceases to exist. Clearly, the complete military defeat of one of the parties to the conflict, the demobilization of one or both of the non-State parties, or the dissolution of the State party means that the armed conflict has come to an end.⁵⁸

2. 2. There is a lasting cessation of armed confrontations without real risk of resumption. If both parties continue to exist, the armed conflict will also continue to exist until there is a lasting cessation of armed confrontations without real risk of resumption, based on a factual assessment on the ground. A party may, for instance, decide to temporarily suspend hostilities, or the pattern of violence may be such  –  owing to culture, climate, diplomacy or other causes  –  that there are periods of cessation and resumption of armed confrontations. In such cases, the conflict will continue even in the face of any intervening ceasefires, armistices or peace agreements, which, while being indicators, are not dispositive in determining the end of a NIAC. Rather, a lasting cessation necessarily excludes any temporary lulls in fighting or oscillations in intensity. Indicators of a lasting cessation of armed confrontation without a risk of resumption include, inter alia:

   • • the effective implementation of a peace agreement or ceasefire;

   • • declarations by the parties, not contradicted by the facts on the ground, that they definitely renounce all violence;

   • • the dismantling of government special units created for the conflict;

   • • the implementation of disarmament, demobilization and/or reintegration programmes;

   • • the increasing duration of the period without hostilities; and

   • • the lifting of a State of emergency or other restrictive measures.

Conflict trends – 2024

The ICRC classifies armed conflicts solely on the basis of facts and legal criteria established in international humanitarian law.

The trends obtained from this exercise are, for the ICRC, alarming. There are over 120 armed conflicts around the world, which involve over sixty States and 120 non-State armed groups. The ICRC has noted that the number of armed conflicts has steadily risen since the 1990s; worryingly, since the year 2000, the number of non-international armed conflicts has tripled from under thirty to around 100, and the number of international armed conflicts is also on the rise. This upsurge is the result of several factors (many of them discussed in this paper): armed groups sometimes split into factions and emerge as new, independent groups; partnered operations result in conflicts involving coalitions; and places affected by conflict become fertile ground for the further proliferation of armed conflict. The ICRC's largest operations take place in countries affected by armed conflicts; many of them have lasted decades.