(CNN) -- Iran's military on Sunday claimed it shot down a U.S. drone into eastern Iran.
State media cited a military official who identified the aircraft as an RQ-170 Sentinel.
NATO's International Security Assistance Force said a U.S. unarmed reconnaissance aircraft was flying a mission over western Afghanistan -- which borders Iran -- last week when operators lost control.
A U.S. official with knowledge of the incident said the crew operating the unmanned drone reported a loss of flight control just before the drone went down.
U.S. officials believe the drone Iran is referring to may be the same one, but the U.S. government has not confirmed that it was shot down, the source said.
The RQ-170 Sentinel is a stealth drone developed for the Air Force to help provide intelligence, surveillance and reconnaissance. Although the Sentinel was developed for the Air Force, the U.S. official did not say whether it was the U.S. military or the U.S. intelligence community operating the drone at the time of the incident.
The official said the drone's mission was to fly over Afghanistan. American officials over the years have been adamant that U.S. assets do not fly over Iranian air space.
Iranian media reported that the RQ-170 was slightly damaged and in the hands of Iranian forces.
"Armed forces with a dominant control over the country's borders managed to identify and down the invading plane," the Islamic Republic News Agency reported.
The unnamed Iranian military official called it a "clear example of aggression" and added that Iran is "fully ready to counter any aggression," the report said.
In July, Iran's military made a similar claim, saying it downed a U.S. "spy drone" flying near its Fordo nuclear enrichment plant in Qom province. But Iran backtracked on the statement a few days later, saying the incident was actually part of a training exercise.
CNN's Barbara Starr, Mohammed Tawfeeq, and Josh Levs contributed to this report.