The United States has threatened Beijing with new countermeasures after China imposed draconian national security laws on Hong Kong.
Mike Pompeo, the US Secretary of State called the enactment of the sweeping measures a "sad day for Hong Kong, and for freedom-loving people across China" and reiterated the White House's commitment to abolishing the city's special status under US law.
"Per President Trump's instruction, we will eliminate policy exemptions that give Hong Kong different and special treatment, with few exceptions," Mr Pompeo said.
"The United States will not stand idly by while China swallows Hong Kong into its authoritarian maw," he warned.
Hong Kong marked the 23rd anniversary of its handover to China on Wednesday, with protests banned and the city's cherished freedoms looking increasingly fragile.
The commemorations came a day after China passed the law decried by many Western governments as an unprecedented assault on the finance hub's liberties and autonomy.
Hong Kong leader Carrie Lam, a pro-Beijing appointee, hailed the law as the "most important development" since the city's return to Chinese rule in 1997 as she attended a traditional flag-raising ceremony.
But opprobrium poured in from critics and western governments - led by Washington - over fears the law will usher in a new era of mainland-style political repression.
Under a deal ahead of the handover authoritarian China guaranteed Hong Kong civil liberties - as well as judicial and legislative autonomy - until 2047 in a deal known as "One Country, Two Systems".
"(China) promised 50 years of freedom to the Hong Kong people, and gave them only 23," Mr Pompeo said.
Hong Kong activists have called on people to defy a ban on protests and march through the city's main island on Wednesday afternoon.
But it is unclear whether residents will heed that call given the risks posed by the new security law - which came into effect overnight - and increasingly aggressive police tactics towards even peaceful gatherings in recent months.
Police fanned out across the city's main island on Wednesday morning, frequently conducting stop and searches.
Gatherings of more than 50 people are already banned under anti-coronavirus laws, even though local transmissions have ended.