China hinted on Monday that it could retaliate after US President Joe Biden signed into law legislation to boost Taiwan's defences and seeks to get TikTok's Chinese owner to divest from the social media platform.

Biden signed the legislation on a military aid package on Wednesday, with most of the money going to Ukraine to help it fend off Russia's invasion and to Israel. He also signed a separate bill tied to the aid legislation that bans TikTok in the United States if its Chinese owner ByteDance fails to divest the app over the next nine months to a year.

Speaking in Beijing, Chinese Foreign Ministry spokesperson Lin Jian urged the United States not to implement the "negative, China-related" parts of the legislation.

"If the United States clings obstinately to its course, China will take resolute and forceful steps to firmly defend its own security and development interests," Lin said, without elaborating.

The United States is Taiwan's most important international backer and arms supplier even in the absence of formal diplomatic ties. China, which views Taiwan as its own territory, has repeatedly demanded arms sales stop.

Taiwan's democratically-elected government, which rejects China's sovereignty claims, has welcomed the new legislation saying it will help maintain security in the region.