The US Navy claimed it will soon use armed, robotic patrol boats with no sailors on board to escort and defend warships moving through sensitive sea lanes.

The US Navy claimed it will soon use armed, robotic patrol boats with no sailors on board to escort and defend warships moving through sensitive sea lanes.

The technology, adapted from NASA, will transform how the American navy operates and is sure to raise fresh questions and concerns about the widening role of robots in warfare.

The Office of Naval Research on Sunday released the results of what it called an unprecedented demonstration in August involving 13 robotic patrol craft escorting a ship along the James River in Virginia.

In a simulated scenario, five of the robotic patrol boats guarded a larger ship, while eight others were ordered to investigate a suspicious vessel.

The unmanned patrol boats then encircled and swarmed the "target," enabling the mother ship to move safely through the area.

The demonstration, conducted over two weeks, was designed to "replicate a transit through a strait," naval research chief Rear Admiral Matthew Klunder told reporters in a recent briefing.

The demonstration was a "breakthrough" that goes far beyond any previous experiment, he said, adding that similar robotic patrol craft likely will be escorting US naval ships within a year.

The patrol craft, 11-meter (yard) long vessels known in the military as rigid hulled inflatable boats, are usually operated by three or four sailors. But outfitted with the robotic system, a single sailor could oversee up to 20 of the vessels.