UPDATE: The Pentagon says China has agreed to return the underwater drone. The original post is below.

China has seized a US underwater drone and the standoff is escalating. The US says the drone was a scientific research vessel, the Chinese say it was spying on their submarines in Chinese waters. It’s another in a series of escalating actions China is taking.

Is this because of Donald Trump accepting a phone call from the president of Taiwan and his increasing anti-China rhetoric? Maybe. And it’s interesting to note that a retired Chinese admiral, speaking at a conference sponsored by a state-run newspaper, called out the president-elect by name:

“If Trump and the American government dare to take actions to challenge the bottom line of China’s policy and core interests, we must drop any expectations about him and give him a bloody nose.”

More from the New York Times:

According to a Pentagon account, a Chinese Navy vessel that was shadowing the Bowditch — a common practice in the South China Sea — pulled up not far from the vessel. It then dispatched a small boat to seize the drone as the American crew was recovering it from the water, the Pentagon said. The Pentagon described the vehicle as an unclassified “ocean glider” system used to gather military oceanographic data such as salinity, water temperature and sound speed.

An American naval expert did not disagree with Mr. Wu’s notion of what the Americans were probably doing. “Warfare and surveillance in the age of drones has not yet developed an agreed-upon set of rules,” said Lyle J. Goldstein, associate professor at the China Maritime Studies Institute at the U.S. Naval War College, in Rhode Island.

“This is increasingly a major problem as both China and the U.S. are deploying ever more air and naval drones into the contested waters and airspace of the Western Pacific,” he said.

The seizure was possibly another demonstration by Beijing that it can irritate the United States in a gray zone, just under the threshold of actual hostilities, Mr. Goldstein said. He said it was a time for “cooler heads to prevail,” to halt a cycle of escalation that “cannot end well for either side.”