WASHINGTON -- A U.S. Predator drone aircraft conducting classified surveillance over the Persian Gulf was "approached" Tuesday by an Iranian fighter jet, which turned away after a nearby U.S. Air Force jet issued a radio warning, the Pentagon said in a statement.
"The Iranian aircraft departed after a verbal warning," the statement said.
The incident, which was not disclosed for two days, is at least the third time U.S. and Iranian military forces have faced off over American spy drones in the past 15 months, and it inevitably raised concerns of a more serious confrontation.
The Obama administration has stepped up military and intelligence surveillance flights near Iranian airspace and moved warships and other military assets to the Middle East in connection with the increasing Western pressure on Iran to suspend its nuclear development program.
The Pentagon said Thursday that the Predator drone was on a "routine classified surveillance flight over international waters," and was being escorted by two U.S. Air Force jets when an Iranian F-4 fighter was detected more than 16 miles away.
One of the U.S. jets flew within two miles of the Iranian warplane and made radio contact, a Defense official said.
After the incident, the Pentagon said, "the United States communicated to the Iranians that we will continue to conduct surveillance flights over international waters consistent with long-standing practice and our commitment to the security of the region."
"We reserve the right to protect our military assets as well as our forces," the statement added.
The Pentagon initially said the Iranian fighter jet had fled after the U.S. jet had dropped a warning flare, but that account was later corrected. "Updated reporting indicates that no flare was discharged," the revised statement said.
In December 2011, a secret U.S. spy drone crashed inside Iran after what U.S. officials privately said was a malfunction. Iranian officials claimed that they had brought down the craft by jamming its guidance system. They later put out video footage of the captured aircraft, as well as aerial video they said they had taken from it.
Last November, the Pentagon said an Iranian fighter fired multiple times at another Predator drone that U.S. officials said was over international waters, but the slow-moving drone was not hit.