The Iranian military says it has captured an unmanned US drone in its airspace over Gulf waters. The Revolutionary Guards said they had brought down a ScanEagle aircraft - one of the smaller, less sophisticated drones employed by the Americans. Rear Admiral Ali Fadavi, quoted by the Fars news agency, said the drone had conducted several reconnaissance flights over the Gulf in recent days before being caught. There has been no comment from the US. The ScanEagle drone is a low-cost, long-endurance aircraft built by Insitu, a subsidiary of Boeing. Rear Adm Fadavi said that "such drones are usually launched from large warships". The Revolutionary Guards are an elite unit of the Iranian military which operate their own naval forces.