Warnings as a Precautionary Measure: Gaza

by | Jun 23, 2021

Warnings. Rashaad Valley, Iraq 2008. U.S. Army drop leaflets. U.S. Air Force Staff Sgt. Samuel Bendet.

On May 15, the Israel Defense Forces (IDF) gave advance warning of an airstrike against the Al Jalaa Tower in Gaza. IDF operational summaries of Operation Guardian of the Walls highlight extensive use of warnings in furtherance of the recognized obligation to take precautions in attack. The IDF applied similar warnings during the 2014 Gaza Conflict. In both instances, several different media were used, including leaflet drops, phone calls, text messages, and media broadcasts, in some cases simultaneously.

Despite these efforts, humanitarian observers have criticized the IDF for perceived failures to give warnings prior to attacks that resulted in the death or injury of civilians and damage to civilian objects. More recently, it has been suggested that the IDF’s advance notifications constituted threats rather than warnings because the targets struck were not lawful military objectives, that an attacking force must always warn of attacks that may affect civilians, and that this requirement was not met in recent IDF actions.

These criticisms seem to overlook the qualified nature of the law of armed conflict obligation to warn—it is an obligation of conduct that cannot be judged solely by the outcome of an attack. This post revisits the scope of the obligation to warn in light of recent events. It assesses when the obligation to warn applies, and what constitutes an effective warning.

Warnings as a Precaution in Attack

The key provision on warnings is codified by Additional Protocol I (AP I), Article 57(1). This provision requires that “(i)n the conduct of military operations, constant care shall be taken to spare the civilian population, civilians and civilian objects.” In the narrower context of attacks, Article 57(2) lays down complementary rules of practical application in support of the overarching obligation to take constant care. Amongst these rules, Article 57(2)(c) articulates the obligation to warn:

… effective advance warning shall be given of attacks which may affect the civilian population, unless circumstances do not permit.

Although Israel is not a signatory to AP I, its continuing practice reflects a broader consensus of States, namely that the obligation to warn is a rule of customary international law applicable in both international and non-international armed conflicts.

Attacks That May Affect the Civilian Population

The obligation to warn applies to attacks that may affect the civilian population.

Warnings can mitigate the risk of civilian harm in two ways. First, they give civilians time to take measures to protect themselves and their property from the effects of an attack. Second, warnings enable the belligerent exercising control over the territory to take precautions against the effects of an attack—for example, by withdrawing emplaced military objectives from heavily populated areas. If an attack is not expected to place the civilian population in danger, neither of these actions is necessary.

The fact that danger to the civilian population is the condition precedent for advance notification of attacks is discernible from the negotiating history of AP I. In addition, the basic rule of protection set out in Article 51(1) expressly identifies the “dangers arising from military operations” as the hazard that the broader targeting rules address. Accordingly, to affect the civilian population, an attack’s results must go beyond the inevitable inconvenience to civilians who find themselves caught between the parties to an armed conflict.

The corollary is that not every urban attack requires advance notice. If the information reasonably available to a military commander indicates that civilians are unlikely to suffer death or injury, or if the elected means and methods of attack are expected to limit the effects of an attack to military objectives, then the obligation to warn will not arise. In the case of the strike against the Al Jalaa Tower, however, the IDF decision to warn indicates an expectation of danger to the civilian population.

Unless Circumstances Do Not Permit

When an attack poses danger to the civilian population, an attacking force must give a warning unless circumstances do not permit it. In practical terms, therefore, the obligation to warn is not absolute. For instance, a warning is unnecessary if it would unduly compromise the ability of the attacking force to successfully conduct an attack. This exception stems from the Hague Regulations, Article 26, which dispensed with the requirement for warning in the case of assaults against defended towns.

By logical extension, a warning is also unnecessary in cases where it might increase the risk to the civilian population. This could happen, for example, where there are reasonable grounds to believe that the adversary will respond to the warning of impending attack by deploying involuntary human shields around the announced target to raise the humanitarian costs of the strike for the attacking force.

Given the historical provenance of the warning rule, there is general acceptance that circumstances may not require a warning when the “element of surprise in an attack is a condition of its success.” In particular, advance notification will be impracticable if it allows the enemy to consolidate its defensive positions, to move mobile military objectives, or to remove essential equipment from a building about to be attacked. 

Circumstances may not permit a warning to be given where targets are situated in territory beyond the effective control of the attacking force. Yet just as the element of surprise may be the only advantage for an attacking force in those circumstances, so too might a warning to civilians in the vicinity of the military objective be the only way of mitigating civilian harm. This is particularly so in cases where the adversary deliberately chooses to operate amidst the civilian population, and so avoids its obligation to distinguish military objectives. In such cases warnings may even simplify the conduct of the attack—if civilians leave as a result of the warning, their absence will reduce the risk of incidental loss thereby providing the attacking force with increased operational freedom to engage the target. Simply put, warnings of attack can benefit both civilians and the attacking force; they are not a zero-sum game.

The use of warnings to balance military and humanitarian considerations in this way is evident in the attack against the Al Jalaa Tower. In its social media messaging, the IDF highlighted that their advance notification allowed Hamas and Islamic Jihad to remove items from the building but that this was, in their view, a price worth paying to protect civilians. As an earlier Articles of War post observes, if the IDF reports are accurate, by surrendering the element of surprise, and thus military advantage in favor of generating a humanitarian benefit, the warning given went further than required by the law of armed conflict.

Effective Advance Warning

If the purpose of a warning is to enable the civilian population to take protective measures, then the warning must be effective. While there is no prescribed form, an effective warning will satisfy three criteria. First, the warning must be timely and given sufficiently in advance to allow civilians to seek protection. Second, it must be given to those civilians whom the attack will affect, or at least to the responsible authorities who control the territory and bear responsibility for the safety of the civilian population. Finally, the warning must make sufficiently clear what the attacking force expects the civilian population to do, be that shelter in place or evacuate.

Provided each of these criteria is satisfied, there is no obligation to use the best means of communication. Rather, the scope of the obligation to warn in any given situation will depend on what is practically possible. Moreover, the warning rule does not require an attacking force to provide the specific timing and location of an attack. Accordingly, a general warning given in advance of a series of strikes may be more effective than a specific warning given only at the last moment once suitable conditions for the attack have crystallized.

Neither is a warning rendered ineffective by the failure of the civilian population to take protective steps. In such scenarios, however, there might be good reasons why civilians are unwilling or unable to leave their homes. Consequently, even if civilians ignore a warning, an attacking force must factor into its proportionality assessment the danger presented to any portion of the civilian population that remains.

Returning to the Al Jalaa Tower strike, assuming the IDF report is correct, it is difficult to discount the effectiveness of the warning given. The protection of the civilian population is the joint responsibility of the attacking force and the belligerent who exercises control over the military objective. Therefore, if there was sufficient time for Hamas and Islamic Jihad to remove equipment from the building then, prima facie, the warning was sufficiently timely and clear to allow protective measures to be taken for the benefit of the civilian population.


In summary, a closer analysis of AP I, Article 57(2)(c) suggests that complaints about the IDF failure to give effective advance warning of recent airstrikes is misfounded. As an obligation of conduct, the IDF claims to have given notification of the attack via several accessible mediums, thereby providing advance warning to those civilians who were likely to suffer harm or injury as a consequence.  By surrendering the element of surprise to provide this warning, it is also arguable that the IDF went beyond the strict requirement of the obligation to warn. Further, it appears the warning was sufficiently timely and precise to allow the removal of equipment. Thus it is was effective and opportunity existed for the authorities responsible for the protection of the civilian population to take protective measures. On this basis, the information currently available does not substantiate claims that the IDF failed to discharge its obligation to take precautions in attack by not giving effective advance warning of the airstrike against the Al Jalaa Tower.


Major Jon Griffiths is currently a prosecuting officer at the U.K Service Prosecuting Authority and a PhD candidate at the University of Reading, where the focus of his research is urban warfare and the obligation to take precautions in attack.

The views expressed are those of the author writing in a private capacity and do not necessarily represent those of the British Army or the UK Ministry of Defence.