President Joe Biden vowed yesterday that US forces would defend Taiwan militarily if China attempted to take control of the self-ruled island by force, warning Beijing was already "flirting with danger".

The remarks, made in Tokyo where he is meeting with Japan's prime minister ahead of a regional summit today, were Biden's strongest to date on the issue and come amid rising tensions over China's growing economic and military power.

Washington and allies like Japan have framed their tough response to Russia's invasion of Ukraine as a warning to others, especially China, against unilateral military action.

Biden hammered that message home after talks with Japanese Prime Minister Fumio Kishida in which the pair agreed to monitor Chinese naval activity and joint Chinese-Russia exercises.

Biden then went further. Asked if Washington was willing to get involved militarily to defend Taiwan, he replied: "Yes."

In Beijing, foreign ministry spokesman Wang Wenbin swiftly responded, declaring that "no one should underestimate the firm resolve, staunch will and strong ability of the Chinese people in defending national sovereignty and territorial integrity."

"China has no room for compromise or concession," the spokesman said.