The Royal Navy said a British warship was sailing through the Taiwan Strait on September 27, a move that challenges Beijing’s claim to the sensitive waterway and marks a rare voyage by a non-US military vessel.

“After a busy period working with partners and allies in the East China Sea, we are now en route through the Taiwan Strait to visit Vietnam and the Vietnam People’s Navy,” read a tweet from the official account for HMS Richmond, a frigate deployed with Britain’s aircraft carrier strike group.

Local media said it was the first time a British warship had transited through the narrow waterway separating Taiwan and mainland China.

The British navy survey ship HMS Enterprise transited through the strait in 2019. The UK’s defence ministry did not respond to a request for comment.

US warships regularly conduct “freedom of navigation” exercises in the strait and trigger angry responses from Beijing, which claims Taiwan and surrounding waters – and almost all of the South China Sea.

The US and most other countries view those areas as international waters that should be open to all vessels.

China’s initial response to the British warship’s passage was muted on September 27.

“We hope the relevant countries can do more to build mutual trust between countries and uphold peace and security in the region,” foreign ministry spokeswoman Hua Chunying told reporters.