Cluster Munitions and International Humanitarian Law

Background on Cluster Munitions

Cluster munitions are large weapons that contain dozens and often hundreds of smaller submunitions. After being dropped from the air by planes or helicopters or fired from the ground by artillery or rocket launchers, cluster munitions open up in the air and release their submunitions over a wide area. The submunitions from air-dropped cluster munitions are called bomblets, and those from ground-delivered cluster munitions are called grenades. The submunitions often have both antipersonnel and anti-armor effects. With very few exceptions, both cluster munitions and submunitions are unguided weapons. All of the submunitions used in the conflict in Lebanon were unguided.31

The military values cluster munitions because of their wide footprint; they can destroy broad, relatively soft targets, like airfields and surface-to-air missile sites. They can also be effective against targets that move or do not have precise locations. The military advantages of cluster munitions, however, must be weighed against their documented harm to civilians both during and after strikes.

The humanitarian effects of a cluster munition attack are often more serious than those of other types of attacks because of the submunitions’ wide dispersal. Even if a cluster munition hits its target, which is not guaranteed because it is usually unguided, the submunitions may kill or injure civilians within the footprint. The inherent risks to civilian life and property increase when a party uses these weapons in or near populated areas. If cluster munitions are used in an area where combatants and civilians commingle, civilian casualties are almost assured.

Cluster munitions also produce deeply problematic aftereffects because many of the submunitions do not explode on impact as intended. While all weapons have a failure rate, cluster munitions are more dangerous because they release large numbers of submunitions and because certain design characteristics, based on cost and size considerations, increase the likelihood of submunition failure. Manufacturers and militaries have typically indicated that failure rates for submunitions under test conditions range between 5 and 20 percent. Actual failure rates in combat conditions have been higher, including in south Lebanon. As a result, every cluster munition strike leaves some unexploded ordnance. The dud, or initial failure, rate (i.e., the percentage that does not explode) not only reduces the immediate military effectiveness of cluster munitions but also puts civilians at great risk. Unexploded bomblets and grenades are often highly unstable and can explode at the slightest touch or movement, becoming de facto landmines that kill or injure civilians returning to the battle area after an attack.

An unexploded, air-dropped BLU-63 submunition lies hidden in a farmer’s field just outside Beit Yahoun on October 24, 2006. Such US-made submunitions, carried in a CBU-58B, date back to the Vietnam War. © 2006 Bonnie Docherty/Human Rights Watch

At least 14 states and a small number of non-state armed groups have used cluster munitions in at least 30 countries and territories. While the number of conflicts in which cluster munitions have been used is still relatively limited, the danger of the problem growing exponentially is great. A total of at least 76 countries stockpile cluster munitions. Thirty-four countries have produced over 210 different types of cluster munitions, and at least 13 countries have transferred over 50 different types of cluster munitions to at least 60 other countries, as well as non-state armed groups.32

International Humanitarian Law

During the war in Lebanon, Israeli and Hezbollah forces were bound by international humanitarian law, which requires parties to an armed conflict to respect and protect civilians and other persons not or no longer taking a direct part in hostilities. It also limits permissible means and methods of warfare. The most relevant IHL provisions are the four Geneva Conventions of 1949, to which Israel is party, and the First Additional Protocol of 1977, to which it is not.33 Protocol I codified and in some measure expanded upon existing law, particularly relating to the conduct of hostilities. Today, many, if not most, of its provisions are considered reflective of customary international law.34

The principle of distinction is the keystone of the law regulating protection of civilians during hostilities. It requires parties to a conflict to distinguish at all times between combatants and civilians. Parties may not attack civilians and civilian objects and may direct attacks against only military objectives.35 Military objectives are members of the armed forces, other persons taking a direct part in hostilities, and “those objects which by their nature, location, purpose or use make an effective contribution to military action and whose total or partial destruction, capture or neutralization, in the circumstances ruling at the time, offers a definite military advantage.”36 IHL prohibits attacks “of a nature to strike military objectives and civilians or civilian objects without distinction.”37 Indiscriminate attacks include those that “are not directed at a specific military objective,” those that use means that “cannot be directed at a specific military objective,” and those that “employ a method or means of combat the effects of which cannot be limited.”38 Bombardments that treat as a single military objective a number of clearly separated and distinct targets are indiscriminate as well.39

Another key principle is that of proportionality. Attacks that violate the principle of proportionality are indiscriminate because they are “expected to cause incidental loss of civilian life, injury to civilians [or] damage to civilian objectives…which would be excessive in relation to the concrete and direct military advantage anticipated” from that attack.40  

When conducting military operations, parties to a conflict must take constant care to spare the civilian population and civilian objects from the effects of hostilities. Precautions include:

  • Doing “everything feasible to verify” that the objects to be attacked are military objectives and not civilians or civilian objects or subject to special protection.

  • Taking “all feasible precautions in the choice of means and methods” of warfare so as to avoid and in any event minimize “incidental loss of civilian life, injury to civilians and damage to civilian objects.”

  • Refraining from launching attacks “expected to cause incidental loss of civilian life, injury to civilians, [or] damage to civilian objects…which would be excessive in relation to the concrete and direct military advantage expected.”

  • When circumstances permit, giving “effective advance warning…of attacks which may affect the civilian population.”

  • “When a choice is possible between several military objectives for obtaining the same military advantage,” carrying out the attack that may be “expected to cause the least danger to civilian lives and civilian objects.”

  • Avoiding “locating military objectives within or near densely populated areas.”

  • Endeavoring “to remove the civilian population…from the vicinity of military objectives.”41

  • The enemy’s failure to respect one or more of these precautions does not permit the other party to the conflict to ignore precautions on its side.

    Medical establishments benefit from special protection under international humanitarian law. Hospitals and other medical units must be “respected and protected” and must not be the object of attack.42 They must not be used “to shield military objectives from attack.”43 They lose this protection, however, if they are used to commit “acts harmful to the enemy.”44

    With respect to individual responsibility, violations of international humanitarian law when committed with criminal intent are war crimes. This would include deliberate attacks on civilians, as well as indiscriminate or disproportionate attacks when committed with knowledge or reckless indifference to their illegal character. Individuals may also be held criminally liable for attempting to commit a war crime, as well as planning, instigating, assisting in, facilitating, aiding, or abetting a war crime.45 Commanders and civilian leaders may be prosecuted for war crimes as a matter of command responsibility when they knew or should have known about the commission of war crimes and took insufficient measures to prevent them or punish those responsible.46

    International Humanitarian Law Applied to Cluster Munitions

    Cluster munitions raise serious concerns under the above provisions. Cluster munition strikes in or near population centers are likely to be indiscriminate because the weapons cannot be precisely targeted. Cluster munitions are area weapons, useful in part for attacking dispersed or moving targets. Most cannot, however, be directed at specific fighters or weapons, a limitation that is particularly troublesome in populated areas, even if there is a specific legitimate military target within the area. When cluster munitions are fired into civilian areas, civilian casualties and damage to civilian infrastructure are difficult to avoid.

    Whether a cluster strike is discriminate must be judged not only on its immediate impact but also its later effects. Cluster duds do not distinguish between combatants and civilians and will likely injure or kill whoever disturbs them. The effects become more dangerous if the submunitions litter an area frequented by civilians or the dud rate is high (due to poor design, age, use in inappropriate environments, or delivery from inappropriate altitudes or distances). The large number of submunitions released by cluster munitions combined with a high dud rate makes the aftereffects in civilian areas particularly deadly. In that situation, the unexploded duds take on a character similar to antipersonnel landmines, which have been banned under international law.47

    The lawfulness of an attack may also be determined by its disproportionate effect on civilians. A cluster attack will be unlawfully disproportionate if expected civilian harm outweighs anticipated military advantage.

    This does not just mean immediate civilian losses, but also encompasses casualties over time—it is increasingly accepted that long-term effects should be a factor in judging the proportionality of cluster munition attacks. The preamble of the final declaration of the Third Review Conference of the Convention on Conventional Weapons recognizes “…the foreseeable effects of explosive remnants of war on civilian populations as a factor to be considered in applying the international humanitarian law rules on proportionality in attack and precautions in attack.”48 States parties, including Israel and the United States, adopted this language on November 17, 2006.

    Taking into account both strike and post-strike civilian harm greatly increases the likelihood that the loss will be excessive in relation to the military advantage, especially if an attack occurred in a populated area or an area to which people might return. Based on its field research in Yugoslavia, Afghanistan, and Iraq, as well as Lebanon, Human Rights Watch believes that when cluster munitions are used in any type of populated area, there should be a strong, if rebuttable, presumption that an attack is disproportionate.

    States are legally bound to minimize civilian harm. Taking “all feasible precautions” to do so entails a legal obligation to choose means and methods of attack that would minimize harm to civilians, or even to cancel or refrain from attack where the attack can be expected to cause disproportionate harm to civilians.49 Given the high potential for cluster weapons to be disproportionate and indiscriminate, states should avoid strikes in or near population centers and minimize the long-term effects of duds.

    31 Israel is not known to possess cluster munitions with individually guided submunitions, such as the Sensor Fuzed Weapons produced in the United States.

    32 Human Rights Watch internal research; Human Rights Watch, “Dirty Dozen Chart,” December 2007, www.stopclustermunitions,org; Human Rights Watch, “Updated Human Rights Watch Cluster Munition Information Chart,” June 2007, ; Human Rights Watch, “Human Rights Watch Cluster Munition Information Chart,” March 2006,

    33 Geneva Convention for the Amelioration of the Condition of the Wounded and Sick in Armed Forces in the Field (First Geneva Convention), adopted August 12, 1949, 75 U.N.T.S. 31, entered into force October 21, 1950; Geneva Convention for the Amelioration of the Condition of Wounded, Sick and Shipwrecked Members of Armed Forces at Sea (Second Geneva Convention), adopted August 12, 1949, 75 U.N.T.S. 85, entered into force October 21, 1950; Geneva Convention Relative to the Treatment of Prisoners of War (Third Geneva Convention), adopted August 12, 1949, 75 U.N.T.S. 135, entered into force October 21, 1950; Geneva Convention Relative to the Protection of Civilian Persons in Time of War (Fourth Geneva Convention), adopted August 12, 1949, 75 U.N.T.S. 287, entered into force October 21, 1950 [hereinafter Fourth Geneva Convention]; Protocol Additional to the Geneva Conventions of 12 August 1949 relating to the Protection of Victims of International Armed Conflicts (Protocol I), adopted June 8, 1977, 1125 U.N.T.S. 3, entered into force December 7, 1978 [hereinafter Protocol I].

    34 See generally International Committee of the Red Cross (ICRC), Customary International Humanitarian Law: Volume 1: Rules (Cambridge: Cambridge University Press, 2005), pp. 3-77.

    35 Protocol I, art. 48.

    36 Ibid., arts. 51(3), 52.

    37 Ibid., art. 51(4).

    38 Ibid., art. 51(4)(a, b, c).

    39 Ibid., art. 51(5)(a).

    40 Ibid., art. 51 (5)(b).

    41 Ibid., arts. 57, 58.

    42 Fourth Geneva Convention, art. 18; Protocol I, art. 12(1).

    43 Protocol I, art. 51(7).

    44 Fourth Geneva Convention, art. 19.

    45 See ICRC, Customary International Humanitarian Law, p. 554.

    46 Ibid., pp. 558-563.

    47 Convention on the Prohibition of the Use, Stockpiling, Production and Transfer of Anti-Personnel Mines and on Their Destruction, adopted September 18, 1997, entered into force, March 1, 1999. As of December 2007, there were 156 states parties. Israel is not party.

    48 CCW Third Review Conference, “Final Declaration,” p. 4.

    49 Protocol I, art. 57(2).