The Chinese foreign ministry says China has lodged "stern representations" with the United States, after President Joe Biden said US forces would defend Taiwan in the event of a Chinese invasion.
China reserves the right to take all necessary measures in response to activities that split the nation apart, foreign ministry spokesman Mao Ning said at a regular media briefing on Monday.
"There is only one China in the world, Taiwan is part of China, and the government of the People's Republic of China is the only legitimate government of China," said Mao.
When asked in a CBS 60 Minutes interview whether US forces would defend the self-ruled island claimed by China, Biden replied: "Yes, if in fact, there was an unprecedented attack."
Asked to clarify if he meant that unlike in Ukraine US forces, men and women, would defend Taiwan in the event of a Chinese invasion, Biden replied: "Yes."
The interview was the latest time that Biden has appeared to go beyond long-standing stated US policy on Taiwan, but his statement was clearer than previous ones about committing US troops to the defend the island.
Asked to comment, a White House spokesman said US policy towards Taiwan had not changed.
"The president has said this before, including in Tokyo earlier this year. He also made clear then that our Taiwan policy hasn't changed. That remains true," the spokesman said.
The CBS interview with Biden was conducted last week. The president is in Britain for Queen Elizabeth II's funeral on Monday.
The US has long stuck to a policy of not making clear whether it would respond militarily to an attack on Taiwan.
In May, Biden was asked if he was willing to get involved militarily to defend Taiwan and replied "Yes ... That's the commitment we made."
In the 60 Minutes interview, Biden reiterated that the US did not support Taiwanese independence and remained committed to a One China policy in which Washington officially recognises Beijing not Taipei