China’s President Xi Jinping has warned that foreign powers will “get their heads bashed” if they attempt to bully or influence the country.
He delivered a defiant speech at an event marking the centenary of the ruling Communist Party on Thursday.
Mr Xi also said Beijing would not allow “sanctimonious preaching”, in remarks widely seen as directed at the US.
It comes as China faces criticism over alleged human rights abuses and its crackdown in Hong Kong.
Relations between the US and China have worsened in recent times over trade, espionage and the pandemic.
The issue of Taiwan is also a major source of tension. While democratic Taiwan sees itself as a sovereign state, Beijing views the island as a breakaway province.
The US, under its own laws, is required to provide Taiwan with the means to defend itself should Beijing use force to take the island back.
On Thursday Mr Xi said China maintains an “unshakeable commitment” to unification with Taiwan.
“No one should underestimate the resolve, the will and ability of the Chinese people to defend their national sovereignty and territorial integrity,” he said.
The 100th anniversary celebrations on Thursday morning saw military jet fly-pasts, cannon salutes and patriotic songs played.
A carefully vetted crowd were in attendance in Beijing’s Tiananmen Square, many of whom were not wearing masks.
The country has seen a media blitz in recent weeks promoting a party-approved version of China’s history.
Hong Kong is also marking its handover anniversary on the same day.