In late 2011, Iran claimed it brought down a CIA spy drone after it entered Iranian airspace from its eastern borders with Afghanistan and Pakistan. The RQ-170 Sentinel drone, which is equipped with stealth technology, was captured almost intact. Tehran later said it recovered data from the drone.
In the case of the Sentinel, after initially saying only that a drone had been lost near the Afghan-Iran border, American officials eventually confirmed it had been monitoring Iran's military and nuclear facilities. Washington asked for it back but Iran refused, and instead released photos of Iranian officials studying the aircraft.