US commanders considered shooting down an unmanned navy helicopter that flew out of control towards the US capital last month before communications were restored, a top US officer said Thursday.

Admiral Sandy Winnefeld, who oversees the country's air defenses, said the August 2 incident presented senior officers with an unprecedented dilemma, as a robotic Firescout helicopter strayed off course after losing ground communications.

"We were watching this very closely," said Winnefeld, head of US Northern Command and NORAD, the joint US-Canadian air defense command.

"It's headed right for the heart of the national capital region," he told defense reporters. "Do you let it run out of gas and hopefully crash in a farmer's field or do you actually take action to shoot it down?"

"You certainly don't want to shoot it down over a populated area if you can avoid it."

The North American Aerospace Defense Command was on the verge of scrambling F-16 fighter jets to intercept the helicopter when operators regained control of the chopper after 20 minutes.

The MQ-8B Fire Scout had taken off from Webster Field at the Patuxent River testing ground in Maryland and broached Washington's restricted air space, but the US Navy said the helicopter never got closer than 40 miles (64 kilometers) from the capital.

The admiral said the military was "not close" to shooting down the helicopter but commanders had reviewed possible options.

"So we were going through all that decision calculus and then fortunately got the word that they'd gotten control of it," he said.

The episode came as the military presses civilian officials at the Federal Aviation Administration (FAA) to ease restrictions on the use of unmanned aircraft over the United States.

Winnefeld acknowledged that last month's incident with the runaway Firescout would only reinforce worries about introducing more unmanned aircraft in US airspace.

"It certainly doesn't help our case anytime there's a UAV (unmanned aerial vehicle) that wanders around a little bit outside of what's controlled air space," he said.

FAA officials have pushed for assurances that sensor systems aboard drones are sufficiently reliable to detect and avoid other planes.

The admiral said at the moment he has no unmanned aircraft at his disposal due to the FAA restrictions and that robotic drones will be increasingly in demand to help respond to natural disasters and other needs.

"I share the FAA's goal that air space operations in the United States be conducted safely," he said, but added that it was important to move quickly to resolve the safety concerns.