Story highlights Iranian plane came within 50 yards of U.S. Navy Sea Hawk copter

Navy copter was on patrol in international airspace

U.S. official think Iranian plane may have been under orders of local commander

Washington (CNN) An Iranian military observation aircraft flew within 50 yards of an armed U.S. Navy helicopter over the Persian Gulf this month, sparking concern that top Iranian commanders might not be in full control of local forces, CNN has learned.

An MH-60R Sea Hawk helicopter approaches the flight deck of the aircraft carrier USS Carl Vinson in November 2014.

The incident, which has not been publicly disclosed, troubled U.S. military officials because the unsafe maneuver could have triggered a serious incident.

It also surprised U.S. commanders because in recent months Iranian forces have conducted exercises and operations in the region in a professional manner, one U.S. military official told CNN.

"We think this might have been locally ordered," the official said.

The incident took place as the U.S. and other world powers meet with Iran in Switzerland to negotiate a deal limiting Tehran's nuclear program. At the same time, Iran has been active in supporting proxies in several hotspots in the Persian Gulf and neighboring regions.

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