The Chafee, a guided missile destroyer, entered China's territorial sea off the Xisha Islands on Tuesday and conducted a so-called "freedom of navigation" operation, without the permission of the Chinese government, Chinese Foreign Ministry spokesperson Hua Chunying said Wednesday.
"China sent military vessels and planes to investigate and identify the U.S. military ship and warned it to leave," Hua said at a regular news briefing.
Xisha Islands are China's inherent territory, and China announced the baseline of territorial waters off these islands in 1996, according to Hua.
She said the U.S. military ship's conduct violated Chinese and relevant international laws, seriously damaged China's sovereignty and security interests, and put the lives of people at the frontline at risk.
Expressing firm opposition to the U.S. move, Hua said China will continue to take resolute measures to protect its territorial sovereignty and maritime interests.
"China urges the U.S. side to respect Chinese sovereignty and security interests as well as the efforts of regional countries to maintain the peace and stability of the South China Sea," Hua said, calling for a stop of such wrong actions.