China on Friday condemned the United States after unauthorized U.S. navy ships sailed near two Chinese island chains in the South China Sea. Beijing also urged the U.S. to stop its frequent dispatches of warships to the region, Chinese Foreign Ministry spokesperson Geng Shuang said. 

The U.S. action violated China's national sovereignty and security, and damaged peace and stability in the region, Geng said. 

In the past two days, a littoral combat ship and a missile destroyer entered the waters adjacent to China's Nansha Islands and Xisha Islands without authorization.

China insists that the islands are its territory. In response, the People's Liberation Army (PLA) organized naval and air forces to track, verify, identify, and warn the ships away, noted the spokesperson.

A spokesperson for the PLA Southern Theater Command also urged the United States to stop provocative actions that Washington calls "freedom of navigation" operations. 

"The Chinese military is determined and capable of safeguarding national sovereignty and security as well as maintaining peace and stability in the South China Sea, no matter what tricks are played by U.S. ships," added the spokesperson.