China: US ship near disputed island a ‘serious offense’

China on Monday said the United States had committed “a serious offense” when a U.S. Navy destroyer sailed near a disputed island in the South China Sea.

China’s Ministry of National Defense issued a report accusing the U.S. of illegally trespassing “into China’s territorial waters.” The report added that China had dispatched military ships and fighter planes to warn the U.S. vessel away from the area.

“The U.S. has seriously undermined mutual strategic trust and the political atmosphere for the development of mutual military relations,” said Wu Qian, spokesperson for China’s Ministry of National Defense.

“It has also threatened safety of front-line soldiers and damaged regional peace and stability gravely.”

A U.S. Navy destroyer on Sunday sailed within 12 miles of Triton Island in the Paracel archipelago — which is claimed by China, Vietnam and Taiwan — as part of a “freedom of navigation exercise,” according to U.S. military officials.

The United States does not recognize China’s sovereignty claim over the islands, and last month Defense Secretary James Mattis said he had spoken to Chinese officials about the issue.

“Our understanding of the problem is very different than their’s, and we had that discussion,” he said following a June 21 meeting with the officials.

China, meanwhile, said it would strengthen its military’s defense ability “according to the level of threat to national security and resolutely safeguard national sovereignty and security,” following the incident.