Cluster bombs are many bombs in one bomb. The military likes them because they are an efficient way to cover a large area with shrapnel and kill many within the blast area. The downside of their use is that many civilians are killed or injured in addition to any enemy soldiers within the blast area. Cluster bombs are designed to kill using thousands of pieces of shrapnel. Not all components of a cluster bomb explode on first use. Some components (bomblets) remain (as much as 25%) potentially lethal for many years afterward. The US military has the goal of reducing the failure rate to under 1% by 2018. However, that will do nothing to reduce the lethality of cluster bombs on first use.