Non-international armed conflicts

Non-international armed conflicts (NIAC) involve either a State fighting organized armed group(s), or organized armed groups fighting each other. For a NIAC to exist, two criteria must be met under Article 3 common to the four 1949 Geneva Conventions and customary international law:

Intensity of armed violence: there must be ‘protracted armed violence’ – meaning that the violence must have reached a certain level of intensity.
Degree of organization: the armed groups must exhibit a certain degree of organization. For state armed forces, the criterion of organization is usually met and they are presumed to be organized.¹

These criteria, which are assessed on a case-by-case basis, are used for the purpose of distinguishing an armed conflict from banditry, unorganized or short-lived insurrections or terrorist activities and are closely related to each other. According to international case-law, certain indicative factors can be used to assess them, including:

For intensity: the number, duration and intensity of individual confrontations; the types of weapons and military equipment used; the material destruction and casualties; the number of refugees and internally displaced persons; the reaction of the government (including the use of force and the application of a legal framework); the reaction and involvement of the international community.
Organization: the presence of some kind of command structure; the ability to define a unified military strategy and use military tactics; the ability to plan, coordinate and carry out military operations; the exercise of some kind of territorial control; the capacity to access to weapons and other military equipment; the ability to recruit and train members; the ability to speak with one voice and to negotiate and conclude agreements, such as ceasefire and peace accords; the existence of internal discipline mechanism, with a responsible command and the ability to implement IHL.²

In NIACs, Additional Protocol II to the 1949 Geneva Conventions (AP II) provides more detailed rules than those that can be found in Common Article 3 1949 Geneva Conventions. For AP II to apply, additional requirements must exist on top of those demanding a certain level of intensity of violence and organization of the armed group. Thus, the NIAC must occur in the territory of a State that is a party to AP II; the armed conflict must occur between governmental armed forces, on the one hand, and organized armed group(s), on the other hand; and the organized armed group(s) must exercise a degree of territorial control that enables them to carry out sustained and concerted military operations and to implement AP II.³

1
ICRC, Updated Commentary on GC I, 2016, paras 493 ff.
2
See for instance, ICTY, Haradinaj, Trial Chamber, Judgment, IT-04-84-T, 3 April 2008, paras 49 and 60, https://www.refworld.org/jurisprudence/caselaw/icty/2008/en/61839.
3
Art 1(1) AP II.