The US Navy's 7th Fleet said in a statement on Friday that an American warship had sailed near the Chinese-controlled Paracel Islands in the disputed South China Sea in a freedom of navigation operation (FONOP).
This is the first such mission under President Joe Biden.
The USS John S. McCain "asserted navigational rights and freedoms in the vicinity of the Paracel Islands, consistent with international law", the statement pointed out, referring to the Arleigh Burke-class guided-missile destroyer.
According to the statement, the FONOP mission challenged the "unlawful restrictions on innocent passage [in the area] imposed by China, Taiwan, and Vietnam".
The remarks came a few weeks after the USS John S. McCain performed a freedom of navigation operation near Vietnam's Con Dao Islands. During the mission, the destroyer purposefully sailed through territorial waters claimed by Vietnam to demonstrate Washington's rejection of the claim.
According to the US Navy, Vietnam has made "excessive maritime claims", and the USS McCain's actions helped "preserve access and navigational freedoms" in line with international law.
In the past, Hanoi has supported FONOPs when carried out in waters claimed by Beijing, but more recently, the US has begun challenging Vietnam's claims as well, particularly in the Spratly Islands in the South China Sea.
In a separate development last month, the US Indo-Pacific Command (INDOPACOM) announced that an aircraft carrier strike group led by the USS Theodore Roosevelt had entered the South China Sea on 23 January "to conduct routine operations" there.
"The Theodore Roosevelt Carrier Strike Group (TRCSG) is on a scheduled deployment to the US 7th Fleet to ensure freedom of the seas, build partnerships that foster maritime security, and conduct a wide range of operations", INDOPACOM said.
Despite having no claims to the territories, the US is also actively engaged in the dispute, repeatedly sending its warships to the South China Sea to fulfill FONOP missions. These infuriate Beijing, who slam such acts as "provocations".