A Chinese warship seized a US Navy unmanned underwater vehicle that was collecting unclassified scientific data in the South China Sea, the Pentagon has said.
Navy Captain Jeff Davis, a Pentagon spokesman, says the US has issued a formal diplomatic complaint and is asking for the drone's return.
Captain Davis says a civilian US Navy ship operated by the military's Sealift Command was recovering two of the unmanned gliders about 50 miles north west of Subic Bay near the Philippines when the Chinese ship approached and took one of the small vessels.
He said the Chinese ship acknowledged radio messages from the US ship, but did not respond to demands the glider be returned.
He said the Dalang Class Chinese ship, which does rescue and recovery missions, sent out a small boat that then took one of the Navy gliders.
The Navy drone is a glider, about 10 feet long and less than two feet wide, that can be programmed and moves automatically through the water collecting data on temperature, salinity, and other scientific facts used for sonar operations.
"It is ours. It's clearly marked as ours. We would like it back, and we would like this not to happen again," Captain Davis told reporters.
He said the USNS Bowditch was stopped in the water when the Chinese ship approached.
The two vessels were within about 500 yards of each other. He said the USNS Bowditch carries some small arms, but no shots were fired.
As the Chinese ship left with the drone, the Pentagon said, its only radio response to the US vessel was: "We are returning to normal operations".