Donald Trump says the US will now treat Hong Kong the same as mainland China.
US President Donald Trump said Tuesday he was ending trade preferences for Hong Kong and signed into law an act that authorises sanctions on banks over China's clampdown in the international finance hub.
In a discursive news conference dominated by attacks on his domestic rivals, Mr Trump declared himself to be the toughest president ever on China, which has emerged as a top nemesis in November elections.
Mr Trump announced that he had issued an executive order, which was not immediately released, on Hong Kong as he predicted decline for the restless city, on which Beijing recently imposed a tough new security law.
"Hong Kong will now be treated the same as mainland China - no special privileges, no special economic treatment and no export of sensitive technologies," Mr Trump said in the White House Rose Garden.
"Their freedom has been taken away; their rights have been taken away," Mr Trump added.
"And with it goes Hong Kong, in my opinion, because it will no longer be able to compete with free markets. A lot of people will be leaving Hong Kong."
Mr Trump also said he had signed into law the Hong Kong Autonomy Act, which passed quickly in Congress earlier this month as Beijing pushed ahead with the security law.
The new US law authorises sanctions against Chinese officials and Hong Kong police seen as infringing on the city's autonomy - and, crucially, any banks that make significant transactions with them.
Politicians hope the new law will force all but provincial Chinese banks to choose between abetting Beijing's efforts in Hong Kong, and being able to conduct transactions in US dollars and operate in the world's largest economy.
"This law gives my administration powerful new tools to hold responsible the individuals and the entities involved in extinguishing Hong Kong's freedom," Mr Trump said.
The White House in a statement acknowledged its concerns that the Hong Kong Autonomy Act, a tougher follow-up to a law last year, limits the president's leeway to waive sanctions.
But the act enjoyed overwhelming bipartisan support, meaning Congress could likely override any veto.
"Today, the United States made clear to China that it cannot continue its assault on freedom and human rights in Hong Kong without severe repercussions," said Senator Chris Van Hollen, a Democrat who spearheaded the law alongside Republican Pat Toomey.
"The Chinese government's aggression merits this swift rebuke," he said.
Beijing defied international warnings by imposing the security law that criminalises subversion and other offenses in Hong Kong, to which it promised autonomy before Britain handed the territory back in 1997.
The law has sent a chill through the financial hub which last year saw massive and sometimes destructive pro-democracy protests.
China has quickly put the law to use, on Monday warning that a primary among pro-democracy parties in which 600,000 Hong Kongers participated was a "serious provocation."
Secretary of State Mike Pompeo earlier Tuesday hailed the primary and called for Hong Kong's legislative elections due in September to be "equally free and fair."
Mr Trump has stepped up pressure on China on multiple fronts, especially on the coronavirus pandemic, news of which Beijing suppressed when the illness first emerged in Wuhan.
Critics both at home and abroad accuse Mr Trump of seeking to divert from criticism of his own handling of COVID-19 in the United States, which has suffered by far the highest death toll of any country.
On Monday, Mr Pompeo also stepped up the tone on the dispute-rife South China Sea, declaring most of Beijing's claims to be illegal.
The Trump administration also last week slapped sanctions on senior Chinese officials over the incarceration of more than one million Uighurs and other Turkic Muslims.