US drones: Close-up look at an unmanned aircraft
4 April 2012 Last updated at 21:54 BST
More pilots are being trained to fly American unmanned aircraft than fighter planes, and most of them are put through their paces at Holloman Air Force Base in New Mexico.
Alastair Leithead tours the base with Col Ken Johnson, commander of the 49th Operations Group. Col Johnson shows off some of the drones and explains their role in American military strategy.