• China claims Taiwan and the Taiwan Strait as part of its territory
  • Beijing termed the passage as "provocative" and said its navy was on high alert
  • Taiwan's defense ministry reported tracking Chinese military aircraft and four naval ships

At least four Chinese warships shadowed the U.S. Navy guided-missile destroyer, USS Higgins, and the Royal Canadian Navy's Halifax-class frigate HMCS Vancouver, as they sailed through the Taiwan Strait on Tuesday.

A report in Taiwan News said the transit was probably accompanied by a Taiwanese military ship. The report quoted independent journalist Duan Dong who posted an image taken from the optical imaging Sentinel-2 satellite on Twitter.

Duan told Taiwan News that four of the ships were from the People's Liberation Army Navy (PLAN).

The U.S. destroyer and a Canadian frigate sailed through the Taiwan Strait on Tuesday in the latest joint operation aimed at reinforcing the route's status as an international waterway. China had termed the passage as "provocative," and said its navy was on high alert.

"The troops of the PLA Eastern Theater Command are on high alert at all times to resolutely counter any threat and provocation and safeguard China's national sovereignty and territorial integrity," Shi Yi, spokesperson for the PLA's Eastern Theater Command, said.

Following the transit by USS Higgins and HMCS Vancouver, the Taiwanese Ministry of National Defense (MND) also reported the tracking of Chinese military aircraft and four naval ships around the island.

According to the report, the image posted on Twitter shows two PLAN ships seen sailing on the opposite side of the median line from the HMCS Vancouver and USS Higgins. Behind the Higgins are three other warships: one just to the east of the median line and two others to the south of the American warship.

The Taiwan News report, quoting Duan said that at least one of the PLAN ships was a Type 054A frigate. It was likely that the other three were also frigates.

Given that Taiwan's defense ministry only announced four PLAN ships, the fifth ship seen trailing the U.S. and Canadian vessels in the satellite image could be from the Taiwan Navy, the report added.

The Taiwan Strait is one of the world's busiest shipping channels. Beijing, which considers self-governing Taiwan as part of its territory, also claims to own the Strait.

The U.S. has long used "freedom of navigation" passages through the Taiwan Strait to push back against Chinese claims, and Western allies have increasingly joined these operations.

The USS Higgins, an Arleigh Burke-class destroyer, in cooperation with the Royal Canadian Navy's Halifax-class frigate HMCS Vancouver, "conducted a routine Taiwan Strait transit Sept. accordance with international law", the US Navy's Seventh Fleet said.

"The ship transited through a corridor in the Strait that is beyond the territorial sea of any coastal State."

Canada said the HMCS Vancouver was en route to join an ongoing mission to enforce UN sanctions against North Korea when it transited with the USS Higgins.

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

Tensions between China and Taiwan are running high since House Speaker Nancy Pelosi visited Taipei in August, after which Beijing responded by ordering several days of military drills. China is also angered by developments in Washington that it believes indicate a shift in U.S. policy away from the long-held one-China policy toward Taiwanese independence.

A US Navy photo shows Canadian frigate HMCS Vancouver in the Taiwan Strait during a routine transit