The Chinese People's Liberation Army (PLA) said Wednesday that it had monitored and warned off the U.S. destroyer USS Benfold after it sailed into waters off the Xisha Islands in the South China Sea without permission from the Chinese government.

The U.S. military's action has infringed upon China's sovereignty and security interests, undermined peace and stability in the South China Sea, and violated international law and norms governing international relations, said Tian Junli, spokesperson for the Southern Theater Command of the PLA in a statement.

"Facts have once again proved that the United States is in every sense a 'security risk maker in the South China Sea' and a 'destroyer of regional peace and stability,'" said Tian.

The theater command stays on high alert at all times to defend national sovereignty and security and peace and stability in the South China Sea, he added.