Cluster munitions, often called cluster bombs, are weapons made up of a hollow shell which contains smaller bombs called submunitions. Each weapon can contain from several to hundreds of explosive submunitions. They are dropped from the air or fired from the ground and are designed to break open in mid-air, releasing the submunitions and saturating an area that can be as wide as several football fields.
Cluster munitions are area-effect weapons: their impact is not limited to one precise target such as an individual tank. Instead, a whole area is scattered with explosives. At the time of use, anybody within the targeted area is very likely to be killed or seriously injured. Since the explosive submunitions are not precision-guided their accuracy can be affected by weather and other environmental factors. Most cluster munitions therefore hit areas outside the military objective targeted.
Submunitions that fail to explode as intended are referred to as “duds” or unexploded ordnance. After a cluster munition strike, these unexploded submunitions remain, like landmines, a fatal threat to anyone in the area. Studies can determine the failure rate or “dud rate” of cluster munitions, by determining the percentage of submunitions which remain as unexploded ordnance after the weapon has been deployed.
The Convention on Cluster Munitions defines the weapon as “a conventional munition that is designed to disperse or release explosive submunitions each weighing less than 20 kilograms, and includes those explosive submunitions.”
Certain weapons containing submunitions are allowed under the Convention on Cluster Munitions, such as weapons with submunitions designed for smoke, flare, and electronic counter-measures. Article 2.2 of the convention sets out five minimum technical characteristics for weapons that avoid indiscriminate area effects and the risks posed by unexploded ordnance. A weapon that contains submunitions, but that possesses all five of these characteristics is not prohibited by the Convention on Cluster Munitions.