Iran claimed it has captured a US drone, an unmanned military aircraft, that entered Iranian airspace over the Persian gulf. But a US defense official denied this report, saying all US Navy drones operating in the Middle East are accounted for. The US official also stressed that drone operations only take place in internationally recognized air space. Iranian officials identified the drone as a Scan Eagle, an unmanned aircraft with a wingspan of about 10 feet capable of flying for 24 hours without refueling. It is used in the military for surveillance operations. Exactly one day ago, in Dec 4, 2011 Iran shot down another US drone, a MQ-1 Predator, conducting a surveillance mission over international waters 16 miles off the coast of Iran.