Iranian scientists guided the RQ-170 to ground by 'spoofing' its GPS coordinates - tricking the plane into landing in Iranian territory instead of where it was programmed to touch down.
U.S. officials have blamed the loss of the sophisticated spy plane on a malfunction, but have yet to explain how it was in such pristine condition after its recovery by the Iranians.
U.S. and NATO officials have said it was on a mission to patrol the Afghan-Iran border and had veered off course when it went missing.
The CIA had not informed the Defense Department of the drone's mission when reports first emerged that it had crashed.
One official told the station that the U.S. military 'did not have a good understanding of what was going on because it was a CIA mission.'
In Kabul, U.S. Defence Secretary Leon Panetta did not deny that it had been spying on Iran and said the drone programme carried out 'important intelligence operations which we will continue to pursue.'
The RQ-170 Sentinel is one of the United States' most sophisticated spy planes and flies at up to 50,000 feet.
Iranian officials have said the drone came down over eastern Iran, hundreds of miles from the cluster of nuclear sites in the central and north-west of the country.
An Iranian member of parliament has hit back at former U.S. vice president Dick Cheney, who said President Obama should have ordered an airstrike into Iran to destroy the drone and deny Iranians access to its technology.
Cheney said the Iranians will likely 'send (the drone) back in pieces after they've gotten all the intelligence they can out of it.'
Mean while Leon Panetta said he did not believe Iran would agree to the U.S. request for the drone's return but told Fox News that the stealth missions along the Iran-Afghan border would 'absolutely' continue.
Some Pentagon officials are saying that Iran has not downed any US drone but displayed the fake drone.
Some Pentagon officials are saying that Iran has not downed any US drone but displayed the fake drone.
