The Chinese military followed and monitored a United States warship that illegally entered the waters near Ren'ai Jiao in China's Nansha Qundao, Senior Colonel Tian Junli, spokesperson for the People's Liberation Army Southern Theater Command, said in a statement on Monday.
The theater command organized naval forces to follow and monitor the warship, he said.
"China has indisputable sovereignty over South China Sea islands and their adjacent waters," Tian said, stressing that their troops are always on high alert to resolutely safeguard China's sovereignty and peace and stability in the South China Sea.