Rule 29

Subject to the circumstances ruling at the time, the following activities are examples  of what may constitute taking a direct part in hostilities:

[Commentary]
  1. Defending of military objectives against enemy attacks.
    [Commentary]

  2. Issuing orders and directives to forces engaged in hostilities; making decisions on operational/tactical deployments; and participating in targeting decision-making.
    [Commentary]

  3. Engaging in electronic warfare or computer network attacks targeting military objectives, combatants or civilians directly participating in hostilities, or which is intended to cause death or injury to civilians or damage to or destruction of civilian objects.
    [Commentary]

  4. Participation in target acquisition.
    [Commentary]

  5. Engaging in mission planning of an air or missile attack.
    [Commentary]

  6. Operating or controlling weapon systems or weapons in air or missile combat operations, including remote control of UAVs and UCAVs.
    [Commentary]

  7. Employing military communications networks and facilities to support specific air or missile combat operations.
    [Commentary]

  8. Refueling, be it on the ground or in the air, of a military aircraft which is about to engage in, or which is engaged in, air or missile combat operations.
    [Commentary]

  9. Loading ordnance or mission-essential equipment onto a military aircraft which is about to engage in, or which is engaged in, air or missile combat operations.
    [Commentary]

  10. Servicing or repairing of a military aircraft which is about to engage in, or which is engaged in, air or missile combat operations.
    [Commentary]

  11. Loading mission control data to military aircraft/missile software systems.
    [Commentary]

  12. Combat training of aircrews, air technicians and others for specific requirements of a particular air or missile combat operation.
    [Commentary]

  1. According to the ICRC Interpretive Guidance,[281] a specific act amounting to direct participation in hostilities must meet three cumulative requirements: (i) a threshold regarding the harm likely to result from the act; (ii) a relationship of direct causation between the act and the expected harm; and (iii) a belligerent nexus between the act and the hostilities conducted between the Belligerent Parties. Applied in conjunction, these three requirements permit a reliable distinction between activities amounting to direct participation in hostilities and activities which, although occurring in the context of an armed conflict, are not part of the hostilities and, therefore, do not entail loss of protection against direct attack.

  2. In the ICRC Interpretive Guidance, the “threshold of harm”[282] requirement is explained as follows. For a specific act to qualify as direct participation in hostilities, the harm likely to result from it must attain a certain threshold. This threshold is reached, most notably, by adversely affecting the military operations or military capacity of a Belligerent Party (e.g., use of weapons against the armed forces, interrupting their deployments). Alternatively, the threshold can also be reached by inflicting death, injury, or destruction on persons or objects protected against direct attack (e.g., shelling or bombardment of residential areas, sniping against individual civilians). Direct participation in hostilities does not require the materialization of harm reaching the threshold but merely the objective likelihood that the conduct in question will result in such harm. Therefore, the relevant threshold determination must be based on “likely” harm, that is to say, harm which may reasonably be expected to result from an act in the prevailing circumstances.

  3. The “direct causation”[283] requirement is explained in the ICRC Interpretive Guidance in the following manner. The civilian population has always contributed to the general war effort, whether through the production and provision of arms, equipment, food, and shelter, or through economic, administrative, and political support. In order to qualify as “direct” rather than “indirect” participation in hostilities, however, there must be a direct causal relation between the act in question and the resulting harm. In this context, direct causation means that the harm is brought about in one causal step. Therefore, acts that merely build or maintain the capacity of a Belligerent Party to harm its adversary in unspecified future operations do not amount to “direct” participation in hostilities, even if they are connected to the resulting harm through an uninterrupted chain of events or are indispensable to its causation (e.g., production of weapons and ammunition, general recruiting and training of personnel). Nonetheless, the notion of direct participation in hostilities can include acts which cause harm only in conjunction with other acts (e.g., providing targeting information as part of a specific combat operation), most notably where the act in question is an integral part of a coordinated tactical operation that directly causes the required threshold of harm.

  4. The “belligerent nexus”[284] requirement is explained in the ICRC Interpretive Guidance as being an act amounting to direct participation in hostilities must not only be objectively likely to inflict harm meeting the first two criteria, but it must also be specifically designed to do so in support of a Belligerent Party and to the detriment of another. Belligerent nexus relates to the objective purpose and design of an act or operation as part of the conduct of hostilities and does not depend on the subjective mindset or intent of every participating individual. Armed violence which is not designed to harm a Belligerent Party, or which is not designed to do so in support of another Party, cannot amount to “participation” in hostilities taking place between these Parties. Thus, as a general rule, harm would remain of non-belligerent nature if it is caused: (a) in exercise of authority over persons or territory having fallen into the power of a party to the conflict (e.g., lawful and unlawful use of force against prisoners); (b) as part of civil unrest against such authority (e.g., violent demonstrations or riots); (c) in individual self-defence against violence prohibited by the law of international armed conflict (e.g., civilians forcibly defending themselves against marauding soldiers); (d) during inter-civilian violence (e.g., uncontrolled looting due to breakdown of law and order); or (e) for reasons otherwise unrelated to the conduct of hostilities (e.g. murder or arson for private motives).

  5. It must be noted that the three criteria established by the ICRC Interpretive Guidance — as summarized in paras. 2 − 4 of the Commentary on this Rule — were not unanimously accepted by the Group of Experts. It was maintained by a number of members of the Group of Experts that these criteria are not part of existing law and impose inappropriate constraints on the scope of direct participation in hostilities.

  6. It is important to stress that the activities listed in Rule 29 are “examples” which may only amount to a direct participation in hostilities “[s]ubject to the circumstances ruling at the time”. According to the ICRC, these examples can amount to direct participation in hostilities only if they meet the three cumulative requirements of threshold of harm, direct causation and belligerent nexus set out in its Interpretive Guidance.

  1. ICRC Interpretive Guidance, “Direct Participation in Hostilities as a Specific Act”, at pages 43–45 and “Constitutive Elements of Direct Participation in Hostilities”, at pages 46–64.

  2. ICRC Interpretive Guidance, at pages 47–50.

  3. ICRC Interpretive Guidance, at pages 51–58.

  4. ICRC Interpretive Guidance, at pages 58–64.

  1. The conduct of hostilities comprises not only offensive, but also defensive acts of violence against the enemy. In principle, therefore, the defence of military objectives against enemy attacks is a clear case of direct participation in hostilities. On the definition of “attacks”, see Rule 1 (e). On the definition of military objectives, see Rule 1 (y) and Rule 22.

  2. Particularly where Belligerent Parties resort to the use of private contractors, it may not always be easy to determine the precise nature of their activities. For example, when they are assigned to defend certain persons or objects, the line between such defence against enemy attacks (amounting to direct participation in hostilities) and against crime or violence unrelated to the hostilities (qualifying as law-enforcement, defence of self or others) may be thin.


Rule 29 (ii) shows that direct participation in hostilities includes acts which are likely to directly harm the enemy (e.g., tactical and operational planning to do harm), even though the person planning does not actually carry out the plan and may be geographically remote from where the plan is carried out.

  1. On the definition of CNAs, see Rule 1 (m). On the definition of electronic warfare, see Rule 1 (p).

  2. Depending on the precise nature of CNA, they may directly cause death, injury or destruction, or system malfunctions adversely affecting the military capacity or military operations of the enemy. When such operations do so, they may amount to direct participation in hostilities. However, mere hacking into the intranet of a military base will not automatically fall under Rule 29 (iii).


“Target acquisition” covers the identification and localization of targets for engagement. It encompasses providing detailed intelligence data about enemy forces and locating them with sufficient accuracy to permit continued monitoring or target designation and engagement.

Planning as well as preparation of a mission involving air or missile attacks can amount to direct participation in hostilities, whereas involvement in the planning of the war effort in general is insufficiently specific to meet the requirements of direct participation in hostilities.

The use of weapons systems during combat operations will almost invariably qualify as direct participation in hostilities. It bears clarifying, however, that no temporal or geographic proximity is necessarily required. While the use of delayed (e.g., mines, booby-traps or timer-controlled devices), or remote-controlled (e.g., missiles, UAV/UCAV) weapons-systems may be temporally or geographically remote from the resulting harm, such activities may qualify as direct participation in hostilities.

  1. To the extent that the use of communications networks and facilities supports specific air or missile combat operations — e.g., through the transmission of orders, intelligence, or other tactical data — such activities qualify as direct participation in hostilities.

  2. Rule 29 (vii) applies only to the use of military communications networks and facilities. Whether the use of civilian networks and facilities constitutes direct participation in hostilities will depend on the special circumstances of such use.

  1. The refuelling of military aircraft engaged in, or about to engage in, air or missile combat operations amounts to direct participation in hostilities because it constitutes either a part of an ongoing hostile act or, respectively, a measure preparatory to such an act.

  2. Conversely, the refuelling of military aircraft that are neither engaged in, nor about to engage in air or missile combat operations does not necessarily qualify as direct participation in hostilities.

  3. “[A]bout to” means that the engagement of the aircraft in a specific air or missile combat operation is imminent.

  1. The loading of ordnance or equipment onto military aircraft engaged in, or about to engage in, air or missile combat operations constitute either a part of an ongoing hostile act or, respectively, a measure preparatory to such an act and, therefore, amounts to direct participation in hostilities.

  2. Conversely, the loading of ordnance or equipment onto military aircraft that are neither engaged in, nor about to engage in, combat operations does not qualify as direct participation in hostilities.

  3. On the expression “about to”, see paragraph 3 of the Commentary on Rule 29 (viii).

  1. The servicing and repairing of military aircraft engaged in, or about to engage in, air or missile combat operations constitute either a part of an ongoing hostile act or, respectively, a measure preparatory to such an act and, therefore, amounts to direct participation in hostilities.

  2. Conversely, the servicing and repairing of military aircraft that are neither engaged in, nor about to engage in, combat operations, may maintain or build the military capacity of a party to the conflict, but does not qualify as direct participation in hostilities (e.g. regular maintenance).

  3. On the expression “about to”, see paragraph 3 of the Commentary on Rule 29 (viii).

  1. The loading of mission control data to software systems of military aircraft/missiles always amounts to direct participation in hostilities.

  2. The term “mission” means that the loading of data is part of an air or missile operation.

  3. “Mission control data” refers to data for a specific sortie.

  4. Rule 29 (xi) does not apply to the loading of mission control data for medical aircraft.

  1. The preparation and training of aircrews, air technicians and others with a view to the execution of a predetermined air or missile combat operation constitutes a measure preparatory to a specific hostile act and, therefore, amounts to direct participation in hostilities. This follows from the fact that the training needs to be for “specific requirements of a particular air or missile combat operation”.

  2. Conversely, general preparation and training of aircrews, air technicians and others for unspecified military operations to be executed in the future may maintain or enhance the military capacity of a party to the conflict, but does not qualify as direct participation in hostilities.

Categories: Section F: Direct Participation in Hostilities