A US destroyer and a Canadian frigate sailed through the Taiwan Strait on Tuesday in the latest joint operation to bolster the route’s status as an international waterway.

Beijing considers both democratic Taiwan and the narrow body of water that separates the island from mainland China – one of the world’s busiest shipping lanes – its property.

The United States has used long passages of “freedom of navigation” across the Taiwan Strait to crack down on Chinese claims, and Western allies have increasingly joined those operations.

The USS Higgins, an Arleigh Burke-class destroyer, was operating in cooperation with the Royal Canadian Navy’s Halifax-class frigate HMCS Vancouver,” the 20th Seventh Fleet said.

“The ship passed through a corridor in the strait that lies beyond the territorial sea of ??a coastal state.”

Canada said HMCS Vancouver is on course to join an ongoing mission to enforce UN sanctions on North Korea if it transits on the USS Higgins.

“Today’s routine cross-strait transit demonstrates our commitment to a free, open and inclusive Indo-Pacific,” Canadian Defense Minister Anita Anand said in a statement, using a different term for the Asia-Pacific region.

A spokesman for China’s Eastern Theater Command described the recent transit as “public hype.”

“The troops are always on high alert, resolutely resisting all threats and provocations, and resolutely defending national sovereignty and territorial integrity,” Colonel Shi Yi said, according to Chinese state broadcaster CCTV.

British, Canadian, French and Australian warships have made passages through the Taiwan Strait in recent years, sparking protests from Beijing.

They also frequently navigate the South China Sea, another important shipping area that Beijing insists falls within its domain despite a 2016 Hague ruling that dismissed its claims as well as competing claims from several neighbors.

The last time US and Canadian warships sailed through the Taiwan Strait was 11 months ago when the destroyer USS Dewey and the frigate HMCS Winnipeg made the voyage.

The last joint passage came a day after President Joe Biden again stated that US troops would come to the aid of Taiwan in the event of a Chinese invasion.

This was the fourth time Biden had made such comments, despite Washington’s longstanding official policy of “strategic ambiguity” – designed to both deter a Chinese invasion and deter Taiwan from provoking Beijing by formally proclaiming independence.

Each time after Biden’s comments, the White House has said there was no change in US policy toward Taiwan.