Nov. 8, 2012  -- The Pentagon disclosed today that an unarmed U.S. military Predator surveillance drone was fired at by Iranian military jets last week in international airspace over the waters of the Persian Gulf.

Officials stressed that the U.S. drone had never entered Iranian territory and that the entire incident occurred in international airspace. The drone was not hit by the plane's gunfire and was able to return to its undisclosed base in the region..

At a Pentagon briefing, spokesman George Little told reporters that the incident had occurred last Thursday at approximately 4:50 a.m. Eastern Time when an unarmed Predator drone "conducting routine surveillance" over the Gulf "was intercepted by Iranian Su-25 Frogfoot aircraft and was fired upon with guns."

The incident occurred 16 nautical miles off the Iranian coastline, said Little. The internationally recognized territorial limit of waters and airspace begins 12 nautical miles from a nation's coastline. Though Little did not disclose where the incident occurred a Defense official told ABC News that it occurred in the northern part of the Persian Gulf east of Kuwait.

The White House and Defense Secretary Leon Panetta were informed of the incident as quickly as it happened, as were relevant members of Congress. The incident was not disclosed until today when CNN was first to reveal the details of the incident. Little said that the Pentagon does not talk about classified missions like the one the Predator was undertaking, but decided to go public with details following "the unauthorized leak."

Little said that the United States communicated to Iran via Swiss intermediaries that "we will continue to conduct surveillance flights over international waters over the Arabian Gulf consistent with long-standing practice."

Little described last Thursday's incident as the first time that an unmanned American aircraft has been shot at over the international waters of the Persian Gulf.

When asked if the United States considered the shooting an "act of war", Little said he was "not going to get into legal labels." He added, "The reality is that we have a wide range of options, as I said before, to protect our assets and our forces in the region and will do so when necessary." He later acknowledged that no manned American aircraft had responded to the incident.

The spokesman said that Iranian SU-25 "Frogfoot" aircraft intercepted the drone in international waters and then fired at it with machine guns. The shots missed and the drone moved beyond the 16 nautical-mile range and it was fired upon again though the shots once again missed. At that point "the Iranian aircraft continued to pursue the MQ-1 for some period of time before letting it return to base." Little believed that the Iranian jets tailed the drone for at least "several miles."

When asked if the Iranian misses may have been "warning shots," Little replied, "Our working assumption is that they fired to take it down. You'll have to ask the Iranians why they engaged in this action."

"We believe that they fired at least twice," he added, "and made at least two passes." A Defense official told ABC News that the approaching Iranian aircraft were spotted by one of the cameras aboard the drone. After the first strafing run the official says the Iranian aircraft made a circular pass around the drone to get in position for another strafing run.

Little said that the Pentagon had not disclosed the incident until today's CNN report because it doesn't talk about classified surveillance mission undertaken by drones. "There is absolutely no precedence for this, so this is the first time that a UAV has been fired upon, to our knowledge, by Iranian aircraft. So I wouldn't draw any parallels between this and past incidents. We routinely do not advertise our classified surveillance missions."

Little downplayed the idea that the White House might have asked the Pentagon to not talk about the incident for political reasons given it occurred so close to the upcoming election. "We don't typically comment on classified surveillance missions," he said. "And I'm not going to get into discussions at the classified level that occurred between this department and the White House. They were informed early on."

An unmanned RQ-170 surveillance drone crashed in Iran last December. At the time Iran claimed that it had been shot down, but U.S. officials said a technical malfunction had brought the aircraft down while conducting a secret surveillance mission over Iran for the CIA.

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