An unmanned, underwater U.S. Navy vehicle was stolen from international waters by a Chinese naval vessel near the Philippines Thursday, according to the Pentagon.
The U.S. Navy Ocean Glider Unmanned Underwater Vehicle was on a routine survey collecting data about 50 miles northwest of Subic Bay, in the South China Sea, when a Chinese ship "unlawfully retrieved it," an official with knowledge of the incident told NBC News.
The ship had been shadowing the oceanographic research ship USS Bowditch, where the drone, carrying an unclassified system, was returning, according to the official.
The U.S. has issued a formal diplomatic complaint, though officials told NBC News the issue did not qualify as an act of war.
It comes amid a series of tense exchanges with China, including its sharp rebuke of President-elect Donald Trump's phone call with Taiwan's president.