China says it warned away a US warship that entered waters near the Spratly Islands in the South China Sea on Tuesday.

The Chinese protest against the US warship’s passage through the disputed waters was the first of its kind since July.

According to the statement posted by the People’s Liberation Army’s Southern Theatre Command on its social media account, the USS Chancellorsville guided-missile cruiser “illegally” entered the waters adjacent to the Spratly Islands, known in China as the Nansha Islands, and reefs on Tuesday without the approval of the Chinese government.

The spokesman reiterated the Chinese military’s commitment to protecting the country’s sovereignty and to upholding stability in the South China Sea.

The US Navy’s 7th Fleet has rejected the Chinese accusations as “false,” insisting that USS Chancellorsville had been carrying out a freedom-of-navigation operation (FONOP) in the area, in line with international law.

“The US challenges excessive maritime claims around the world regardless of the identity of the claimant,” it said.

Nansha, known also as the Spratlys, is a vast archipelago, parts of which are claimed by China, Vietnam, Taiwan, Malaysia, Brunei, and the Philippines.

Beijing, Taipei and Hanoi insist foreign military vessels must receive permission or submit an advance notification before sailing through the area.

Washington believes that these demands are “unlawful” and pose “a serious threat to the freedom of the seas, including the freedoms of navigation and overflight [and] free trade” in the South China Sea, through which multiple trade routes traverse.