A common tactic with JDAMs GPS guided bombs is to drop two bombs on the same target, releasing the second as quickly as possible after the first. Sometimes this is done to make sure a vital target gets taken out, in case there is a malfunction ( about ten percent of the time there is a fuse or guidance system failure.) At other times, two JDAMs are dropped one after another in order to reach a target underground. The second bomb will go into the crater created by the first, and the blast will dig a little deeper.