China on Tuesday handed back to the United States an underwater drone it had seized last week in an incident that raised tensions in a relationship that has been tested by President-elect Donald Trump's signals of a tougher policy toward Beijing.
Trump has riled the Chinese leadership by saying he might reconsider US policy toward Taiwan, the self-ruled island the mainland claims as its territory.
The Chinese navy vessel that seized the drone returned it near where it was seized, and it was received by the USS Mustin about 80 kilometers (50 miles) northwest of Subic Bay in the Philippines, Pentagon press secretary Peter Cook said in a statement. Cook said Washington considered the seizure illegal.
"This incident was inconsistent with both international law and standards of professionalism for conduct between navies at sea," he said, adding that the US has called on China to refrain from "further efforts to impede lawful US activities."
The statement said the US would continue to "fly, sail, and operate in the South China Sea wherever international law allows." Such freedom of navigation missions in which US ships sail near China's artificial islands draw warnings and rebukes from Beijing.
A spokeswoman of China's foreign ministry said there was no basis for the Pentagon's assertion that the seizure was unlawful, though she didn't fully explain the position, instead linking it to the US's military presence in the waters, which Beijing considers provocative.
"We have been pointing out that over a long time, the US has been sending aircraft and vessels to conduct close-in reconnaissance and military surveys in waters facing China, which poses threats to China's sovereignty and security," said Hua Chunying, the spokeswoman.
"That is the root cause of the incident," she said, while calling for the US to stop such activities.
