Greg Jaffe and Thomas Erdbrink,
Washington Post 
December 5, 2011
A secret U.S. surveillance drone that went missing last week in western Afghanistan appears to have crashed in Iran, in what may be the first case of such an aircraft ending up in the hands of an adversary.
Iran’s news agencies asserted that the nation’s defense forces brought down the drone, which the Iranian reports said was an RQ-170 stealth aircraft. It is designed to penetrate enemy air defenses that could see and possibly shoot down less-sophisticated Predator and Reaper drones.
A stealthy RQ-170 drone  played a critical role in surveilling the compound in Pakistan where Osama bin Laden was hiding in the months before the raid in which he was killed by U.S. Navy SEALs  in May.
U.S. officials acknowledged Sunday that a drone had been lost near the Iranian border, but they declined to say what kind of aircraft was missing.
“We have no indication that it was brought down by hostile fire,” said a senior Pentagon official, speaking on the condition of anonymity to discuss sensitive surveillance activity.