The HMS Albion, a 22,000 ton amphibious warship carrying a contingent of Royal Marines, exercised its "freedom of navigation" rights as it passed near the Paracel Islands, two sources, who were familiar with the matter but who asked not to be identified, told Reuters.
The Albion was on its way to Ho Chi Minh City, where it docked on Monday following a deployment in and around Japan.
Thank you Britain.
America since 2017 has begun carrying out true freedom of navigation operations (FONOPs) in the region rather than the previous "innocent passage" sailings that only pretended to be FONOPs.
If China's claims aren't challenged regularly, China gains the advantage of being able to say nobody challenges their claims, so they must be valid and enduring.
Which is why China threatened Britain:
China on Friday warned Britain ties were at risk unless it took steps to "rectify" the situation, after a British warship sailed close to South China Sea islands claimed by China, while a major newspaper said sealing a free trade deal could now be harder.
China would like it if only America challenged China's ridiculous claims, so they can claim America is causing problems for everyone. China would likely make deals for free passage with nations that don't conduct FONOPs at the price of recognizing Chinese claims.
Which is why it is important for a lot of countries to join America in carrying out FONOPs in the South China Sea.
It takes a village to defend an international waterway.