The United States has been flying surveillance drones over Iran (search) since last year to look for evidence of nuclear weapons programs (search) and probe air defenses, The Washington Post reported Sunday.
Citing three U.S. officials with knowledge of the effort, the Post said the small, pilotless planes use radar, video, still photography and air filters designed to pick up traces of nuclear activity to gather details not accessible by satellites.
The paper quoted unidentified Iranian, European and U.S. officials as saying the Iranian government, using Swiss channels in the absence of diplomatic relations with Washington, formally protested the incursions.
It reported that one U.S. official acknowledged that drones were being used but said the Iranian complaint focused on manned military aircraft overflights, which the United States denied.
The drones were first spotted by dozens of Iranian civilians in late December, setting off a flurry of local newspaper stories about whether the country was being visited by UFOs (search).
Word of the drones comes on the heels of stepped-up calls by the Bush administration for Iran to submit to international observation of its nuclear activity to ensure that it is not developing nuclear weapons.
When Iranians living along the Caspian Sea and on the Iraq border began reporting sightings of red flashes in the sky, streaks of green and blue and low lights that disappeared moments after being spotted, Iranian air force commanders concluded they were spy drones, the Post said.
It noted that many Iranian officers were trained more than 25 years ago in the United States and are familiar with U.S. tactics.
The Post quoted an unidentified senior Iranian official as saying Iran's National Security Council decided not to engage the pilotless aircraft rather than tip off its air defense capabilities.
The Iranian action to hold back is considered a major policy decision and reflects Iran's belief that an attack is unlikely anytime soon, the newspaper said.
The U.S. government believes Iran is using its nuclear energy program to conceal an effort to manufacture nuclear weapons and is relying, for the time being, on France, Britain and Germany to negotiate curbs on any such efforts.
The Post said U.S. officials confirmed that the drones were deployed along Iran's northern and western borders, first in April 2004 and again in December and January.