A Chinese aircraft carrier sailed through the geopolitically sensitive Taiwan Strait on Friday according to the Taiwan defence ministry, hours before US President Joe Biden and his Chinese counterpart Xi Jinping held a phone call to discuss the ongoing war between Ukraine and Russia.

The Chinese aircraft carrier, Shandong, sailed close to the Taiwanese island of Kinmen that sits opposite the Chinese city of Xiamen, a source with direct knowledge of the matter told Reuters on the condition of anonymity. The ship did not have any aircraft on board, the source further said.

“Around 10:30 a.m. the CV-17 appeared around 30 nautical miles to the southwest of Kinmen, and was photographed by a passenger on a civilian flight,” Reuters quoted the source as saying.

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The Shandong was also reportedly shadowed by the USS Ralph Johnson, an Arleigh Burke guided missile destroyer, but the US Navy did not name the Chinese carrier, and said that the Ralph Johnson “conducted a routine Taiwan Strait transit March 17 [local time] through international waters in accordance with international law.”

China, for its part, said that the Shandong was on a “routine training schedule” and slammed media outlets for associating its ‘routine’ activities with Chinese aggression.

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“We should not associate this with the communication between the heads of state of China and the United States. You may think it is too sensitive. What is sensitive is you, not the Taiwan Strait,” said Zhao Lijian, the spokesperson for the Chinese foreign ministry.

“China always stands for respecting the sovereignty and territorial integrity of all countries,” Zhao further said.

The incident took place before Biden and Xi Jinping spoke and emphasized the need for “peace and security” on the global stage.

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It also came a couple of days after France-based Russian dissident Vladimir Osechkin, citing a purported Russian intelligence document sent by an FSB whistleblower, claimed that China was planning to invade Taiwan in fall this year.

“Xi Jinping was at least tentatively considering the capture of Taiwan in the autumn—he needs his own small victory in order to be re-elected for a third term—there is a colossal power struggle among the [party] elite. Now, after the events in Ukraine, this window of opportunity has shut, which gives the United States the opportunity to both blackmail Xi and negotiate with his [political] rivals on favorable terms,” a letter from the FSB whistleblower to Osechkin read, as per Newsweek.

While Taiwan considers itself to be independent, Beijing maintains that the island is an “inalienable” part of China.