“China appears to be moving from a period of being content with the status quo over Taiwan to a period in which they are more impatient and more prepared to test the limits and flirt with the idea of unification,” a senior US official told the Financial Times. The official said the Biden administration had reached the conclusion after assessing Chinese behaviour during the past two months.

“As we prepare for a period in which Xi Jinping will likely be entering his third term, there’s concern that he sees capstone progress on Taiwan as important to his legitimacy and legacy,” the official added. “It seems that he is prepared to take more risks. “Twenty Chinese warplanes flew into Taiwan’s air defence zone on Friday, marking its biggest incursion. It came one day after the US and Taiwan agreed to boost co-operation between their coast guards.

The rising alarm in the Biden administration matches a warning from Admiral Philip Davidson, head of US Indo-Pacific command, who told senators China could take military action “in the next six years”. Admiral John Aquilino, who is scheduled to succeed Davidson, this week told Congress that there was a wide range of forecasts but “my opinion is this problem is much closer to us than most think” Aquilino said China had taken other “aggressive actions”, including clashes with India on their border that suggested it was emboldened.

“We’ve seen things that I don’t think we expected,” Aquilino told the Senate armed services committee. “That’s why I continue to talk about a sense of urgency. We ought to be prepared today.” Kurt Campbell, the top White House Asia official, told the FT that while China was acting in an increasingly aggressive manner in many areas, it was taking the most assertive activities in its approach to Taiwan.

“We have seen China become increasingly assertive in the South China Sea . . .economic coercion against Australia, wolf warrior diplomacy in Europe, and the border tensions with India,” he said. “But nowhere have we seen more persistent and determined activities than the military, diplomatic and other activities directed at Taiwan.” The FT reported in January that Chinese fighter jets and bombers simulated missile attacks on the USS Theodore Roosevelt aircraft carrier three days after Joe Biden was inaugurated as US president.

The simulation occurred as Chinese warplanes spent two days flying in and out of Taiwan’s air defence zone just days after Biden was sworn in, in what was the largest Chinese exercise in the area until the intrusion on Friday. One US defence official said the incident was not the first time China had simulated attacks on US ships.