"The US guided missile destroyer USS Milius illegally entered the territorial waters of the Chinese Xisha Islands on March 23 without the permission of the Chinese government, thereby undermining peace and stability in the South China Sea," Tian said in a statement on WeChat.
PLA’s navy grouping of the Southern Theater Command escorted the US vessel and warned it to leave the area, the spokesperson added.
Tian also noted that the troops of the Southern Theater Command will continue to maintain a high level of combat readiness and take all necessary measures to resolutely protect national sovereignty and security, as well as peace and stability in the South China Sea.
The South China Sea Dispute
Beijing has long been disputing ownership of several hydrocarbon-rich islands in the South China Sea with several nations in the region. These territories include the Paracel archipelago, the Spratly Islands, and the Scarborough Shoal.
In July 2016, following a lawsuit filed by the Philippines, the Permanent Court of Arbitration in The Hague ruled that the disputed territories of the Spratly archipelago are not considered as islands in the legal sense, but rather rocks or low-tide elevations which do not form an exclusive economic zone.
Beijing did not recognize the decision of the court, calling it invalid.
The tense situation in the sea region is also complicated by the passage of US warships, which, as Beijing has repeatedly said, violate international law and undermine China's sovereignty and security.