Story highlights The U.S. Navy has accounted for all its drones, a U.S. defense official says

United States operates only in internationally recognized air space in the Gulf, says source

The drone was seized as it flew over the Persian Gulf, Iranian state media says

Iran's Revolutionary Guard says the drone was collecting data

Iran's navy has captured what it says is a U.S. drone after it entered Iranian airspace over the Persian Gulf.

However, a U.S. defense official, who could not be named because the official was not authorized to speak to the media, told CNN that whatever the Iranians claim to have, it is not an actively operating U.S. Navy drone.

"The U.S. Navy has fully accounted for all unmanned air vehicles (UAV) operating in the Middle East region. Our operations in the Gulf are confined to internationally recognized water and air space," the source said. The internationally recognized territorial limit is 12 nautical miles off the coast.

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It is not yet clear whether any other branch of the U.S. military or government might have been operating a drone in the area.

Iranian state media quoted Adm. Ali Fadavi, of Iran's Revolutionary Guard Corps, as saying the unmanned aerial device was a ScanEagle.

The device was spotted carrying out "spying operations" in the Persian Gulf area in the past few days and was captured by Revolutionary Guard anti-aircraft squads, according to Iran's official news agency, IRNA.

With a wingspan of just over 10 feet, the ScanEagle is designed to fly for 24 hours or more without refueling and can survive extreme weather conditions, according to its manufacturer. It can be launched from the ground or from a warship.

The ScanEagle is a relatively low-cost, low-tech system and is operated by a number of U.S. allies in the Persian Gulf region.

Iran has not given details of exactly how or when it captured the supposed U.S. device.

Iran's official Press TV channel showed footage of what was purported to be the drone. No identification markings were visible.

Last month, the Pentagon said Iranian jets had fired on a U.S. drone as it flew off the Iranian coastline in the northern Persian Gulf.

The armed MQ-1 Predator was on a routine surveillance mission above international waters, 16 miles off the coast, the Defense Department said.

The latest announcement comes a year to the day after Iran claimed to have shot down another U.S. drone, a high-altitude RQ-170 Sentinel. It created a toy model of the drone, a much more sophisticated device than the ScanEagle, to celebrate its capture.

U.S. officials said the RQ-170 Sentinel, a stealth drone developed for the Air Force to help provide intelligence, surveillance and reconnaissance, had crashed in the Iranian desert after leaving an airbase in Afghanistan.