Cluster bombs are small explosive bomblets carried in a large canister that opens in med-air, scattering them over a wide area. The bomblets may be delivered by aircraft, rocket, or by artillery projectiles.The CBU (Cluster Bomb Unit) 26, which was widely used in Vietnam and Laos, is an anti-personnel fragmentation bomb that consists of a large bombshell holding 670 tennis ball-sized bomblets, each of which contains 300 metal fragments.
CBU's have a high dud rate estimated at 10 to 30 percent. This leaves a lot of ordinance on the ground to cause havoc with soldiers and civilians alike for years to come.