After U.S. President Joe Biden stated that U.S. soldiers would defend Taiwan in the case of a Chinese invasion, the Chinese foreign ministry announced on Monday that China has made "stern representations" to the U.S.

At a routine media conference, Mao Ning, a spokesperson for the foreign ministry, stated that China reserves the right to take all necessary actions in reaction to actions that cause the country to become divided.

"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," Mao remarked.

"We are willing to do our best to strive for peaceful reunification. At the same time, we will not tolerate any activities aimed at secession," she added.

She further encouraged the U.S. to handle Taiwan-related matters "carefully and properly" and to avoid sending the separatist forces vying for Taiwan's independence "wrong signals." She also cautioned the U.S. not to badly harm Sino-U.S. relations or the stability of the Taiwan Strait.

If there was an unprecedented attack, the U.S. would defend the self-governing island, President Biden said in response to a question from CBS 60 Minutes that was aired on Sunday, Sept.18.

The most direct remark on the subject from US President Joe Biden to date, which is certain to enrage Beijing, was that U.S. soldiers would defend Taiwan in the case of a Chinese invasion.

The interview was merely the most recent instance in which Biden seemed to deviate from the U.S.'s long-standing official position on Taiwan. Still, his declaration that US troops would be sent to defend the island was more explicit than prior ones.

The U.S. has long maintained a position of "strategic ambiguity," refusing to say outright whether it would use force to defend Taiwan. A White House representative was contacted for a response and stated that U.S. 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 spokesperson said.

The foreign ministry of Taiwan thanked Biden for reiterating the "rock-solid security commitment of the U.S. government to Taiwan. Taiwan said in a statement that it would keep enhancing its capacity for self-defense and enhance its strong security collaboration with the United States.

When asked in May if he would be willing to use military force to defend Taiwan, Biden responded, "Yes... That's the commitment we made."