"This dangerous and escalatory attack was irresponsible and occurred in the vicinity of established air corridors between Dubai, UAE, and Oman, possibly endangering innocent civilians," said Lieutenant General Joseph Guastella, who commands US air forces in the region.

The Pentagon released a graphic pinpointing the position of the drone on a map of the Strait of Hormuz, the strategic passage through which much of the world's oil passes.

Guastella said the drone, a Navy variant of a high-flying Global Hawk, was over the Strait when it was hit and it fell into international waters.

"At the time of the intercept the RQ-4 was at high altitude, approximately 34 kilometers from the nearest point of land on the Iranian coast," he said, over a video to the Pentagon press briefing room.