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Types of armed conflict

Types of armed conflict
US army soldiers walking up stairs.

International humanitarian law specifically exists to govern and regulate conduct in armed conflict. So, it is important to understand what armed conflict is in order to determine where and when IHL will apply.

There are two types of armed conflict under the Geneva Conventions and their Additional Protocols:

  1. International armed conflict, occurring between two or more States – this includes belligerent occupation; and
  2. Non-international armed conflict, occurring between a State and non-State armed group(s), or between only non-State armed groups. These are often referred to as civil wars.

That said, there are some aspects of IHL that continue to apply in peacetime, extending protections beyond the physical battlespace or at the end of an armed conflict. For example, IHL remains applicable in territories under military occupation, even after the fighting ceases. There are also specific weapons treaties that prohibit not only the use of certain weapons, but also the development, stockpiling, production and sale of those weapons by States.

International armed conflict

Image depicting international armed conflict

International armed conflict (IAC) is the traditional form of warfare that is typically waged between two or more States, for example World War I and World War II. The laws applicable to IAC are primarily found in the Hague Regulations of 1907, the 1949 Geneva Conventions and Additional Protocol I.

Common Article 2 of the Geneva Conventions states,

… the present Convention 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.
The Convention shall also apply to all cases of partial or total occupation of the territory of a High Contracting Party, even if the said occupation meets with no armed resistance.
[A High Contracting Party refers to the nation-States that are parties to the Geneva Conventions. Given the Geneva Conventions have been universally adopted, these provisions can be applied to every nation-State in the world.]
Article 1 of Additional Protocol I provides further guidance, stating that situations of armed conflict include,
‘conflicts in which peoples are fighting against colonial domination and alien occupation and against racist regimes in the exercise of their right of self-determination…’.
As you can see from these extracts, the rules of IHL apply not only to active fighting, but also to situations of occupation, in which one party invades and occupies another, establishing authority and control over part or all of that State’s territory. An example of this is the Israeli-occupied Palestinian territories. These situations are governed by the same rules that apply in an IAC.

Non-international armed conflict

Today, the majority of armed conflicts that take place around the world fall into another category of armed conflict: non-international armed conflict (NIAC). A NIAC is a situation that occurs between a State and an organised armed group, or between such groups within that State’s borders, making it non-international in character.
The laws applicable to NIAC are primarily found in Common Article 3 to the 1949 Geneva Conventions and Additional Protocol II. As is the case in IAC, customary IHL also applies to these situations. Whereas treaty law is derived from written conventions, in which States formally establish certain rules (e.g. the provisions of the Geneva Conventions), customary international law exists independently of treaty law and is made up of rules that come from ‘a general practice accepted as law’. That is, a custom or tradition that is reflected in State practice, which becomes recognised by the international community as law.
Common Article 3 of the Geneva Conventions refers to ‘armed conflict not of an international character, occurring in the territory of one of the High Contracting Parties’. This is not so much a definition, but it is generally accepted that ‘not of an international character’ applies to conflicts where at least one party to the conflict is not a State. For example, the hostilities between Syrian armed groups and the Syrian government and the separate but overlapping hostilities among those Syrian armed groups.
Additional Protocol II adds to Common Article 3, providing a supplementary albeit narrower definition of armed conflict. It includes,
‘conflicts which take 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…’.

In summary:

  • IHL is the specialist body of law that governs armed conflict. Once an armed conflict exists, IHL will apply to any activity related to that conflict.
  • An armed conflict exists whenever there is a use of armed force or belligerent occupation between States (IAC), or when protracted armed violence takes place between States and organised armed groups or between such groups (NIAC).
  • Belligerent occupation is the invasion and establishment of control by one State over all or part of the territory of another. This situation is governed by the laws that apply to IAC.
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