Cluster munitions are weapons that work by dispersing several smaller submunitions, often referred to as bomblets or grenades, over a wide area to destroy dispersed, moving and unseen targets. A cluster munition consists of a canister and several submunitions. After being dropped or fired, the canister opens in mid-air and ejects its cargo of submunitions. These submunitions then scatter over the target area and are designed to explode on impact. Cluster munitions can be delivered from aircraft, via rockets, missiles or bombs. Cluster munitions can also be launched from land-based systems such as artillery, from rockets, artillery shells or missiles.Cluster munitions are area weapons. This means they have effects that are not confined to one precise target, such as an individual tank for example. Other examples of area weapons include napalm or incendiary bombs, or even nuclear weapons. Area weapons can be distinguished from point weapons, which attack single, pre-identified targets. An example of a point weapon is a guided missile set to destroy an anti-aircraft gun.
Depending on the type of cluster munition and the type of delivery system, one cluster munition will strike an area as large as one square kilometre. This impact area is known as a footprint (click to watch). As noted above, cluster munitions are designed to explode on impact, or in other words each submunition will explode on impact, projecting shrapnel that is deadly over a radius of up to 50 metres. However, as with all munitions, a certain number of submunitions in each canister fail to explode on impact due to technical malfunction, inappropriate launch or drop conditions, soft terrain in the target area or a variety of other reasons.
Because of the large numbers of cluster munitions deployed in single attacks and their use in close proximity to each other cluster munitions leave behind a disproportionately large amount of unexploded submunitions. The numbers of unexploded submunitions left behind after conflicts ranges from the thousands (20,000 were cleared in Kosovo in 18 months after the NATO bombing in 1999) to the hundreds of thousands (the UN estimates up to 1 million submunitions were left unexploded after the conflict between Hezbollah and Israel in July and August 2006.) Some cluster munitions contain submunitions that are equipped with self-destruct or self-deactivation mechanisms designed to ensure that they do not remain on the battlefield if they fail to explode on impact.
Self-destruct mechanisms are usually secondary fuses set to function if the primary fuse fails. Self-deactivation mechanisms can incorporate batteries with short lifespans that lose power after a set time period and prevent the submunition detonation mechanism from functioning. Self-destruct mechanisms also experience failure and large numbers of M85 submunitions equipped with self-destruct mechanisms were found unexploded after they were used in Lebanon in 2006.
Still more recent developments in arms production include new generation precision-guided weapons that are still considered by some to be cluster munitions, but that are very different from the cluster munitions in service today. These weapons share a common property with cluster munitions because they have submunitions that separate from a parent munition. However, they can be seen as different from cluster munitions because they have sophisticated guidance systems that use Global Positioning Satellites and infrared sensors to actively seek out and engage targets. It is unclear whether these new precision-guided weapons will fall under the legally defined category of cluster munitions. This depends on the key characteristics used to define the weapon type. Crucially it is the responsibility of governments and stockpilers to provide evidence that certain types of submunition based weapons systems do not pose the same risk as other cluster munitions.
One example of an advanced submunition based weapons system is the sensor-fused weapon. For more information you can download information sheets here on air delivered sensor-fuzed weapons and ground launched sensor-fused weapons or you can watch the following clip that explains how the air delivered sensor-fused weapon works:
There is not yet one accepted legal definition of cluster munitions. However, most attempts to define cluster munitions focus on a few key elements:
- Cluster munitions consist of both a parent carrier munition and several explosive submunitions.
- Cluster munitions function by delivering submunitions over a wide area from aircraft or land-based systems.
- Cluster munitions are area weapons.