The People's Liberation Army sent warnings and drove away a US navy destroyer intruding into Chinese territorial waters of Xisha Islands in the South China Sea, the Ministry of National Defence said on Saturday.
Earlier on Saturday, the USS Curtis Wilbur guided missile destroyer violated China's laws by intruding into Chinese territorial waters, the ministry's spokesman Yang Yujun said in a written statement issued on Saturday night.
"The Chinese troops stationed at the islands and naval ships and airplanes made an immediate response, took countermeasures and conducted identification and verification against the US warship," Yang said.
The US action was "a serious violation of law, it damaged the peace and security of relevant waters and good order, and it is not helpful to regional peace and stability" and the Chinese ministry "expresses resolute opposition", Yang said.
Yang noted that the US side has sent warships or aircraft into China's relevant waters or airspace multiple times, leading to brushes between the two militaries.
"Such actions are technically very unprofessional, they are irresponsible to the safety of servicemen of both sides, and are extremely dangerous in regard to (potential) outcomes," Yang said.
The Chinese military will "take all the necessary measures to firmly safeguard national sovereignty and security no matter what provocative actions are made by the US side", Yang said.