Beijing - China said on Saturday that its military was in contact with its American counterparts on "appropriately handling" the Chinese navy's seizure of a US Navy unmanned underwater glider, one of the most serious incidents between the two countries in years.
The one-sentence comment by the foreign ministry offered no details on what discussions were underway or why China on Thursday seized the drone, which, according to the Pentagon, was being operated by civilian contractors to conduct oceanic research.
The US said it issued a formal diplomatic complaint over the seizure and demanded the drone's return.
China's defence ministry did not immediately respond to questions on the issue.
The drone was seized while collecting unclassified scientific data about 92km northwest of Subic Bay near the Philippines in the South China Sea, which China claims virtually in its entirety, said Navy Captain Jeff Davis, a Pentagon spokesperson.
"It is ours. It's clearly marked as ours. We would like it back and we would like this not to happen again," Davis told reporters. He said the drone costs about $150 000 and is largely commercial, off-the-shelf technology.
The USNS Bowditch, which is not a combat ship, was stopped in international waters on Thursday afternoon and recovering two of the gliders when the Chinese ship approached, Davis said. The two vessels were within about 450m of each other. He said that the USNS Bowditch carries some small arms, but that no shots were fired.
According to the Pentagon, as the Chinese ship left with the drone, which is about 3m long, its only radio response to the US vessel was, "We are returning to normal operations."
President-elect Donald Trump blasted the seizure. Apparently misspelling "unprecedented," he tweeted on Saturday: "China steals United States Navy research drone in international waters - rips it out of water and takes it to China in unpresidented act."
He later reissued the tweet, correcting the spelling to "unprecedented."