China's parliament has approved a decision to go forward with national security legislation for Hong Kong that democracy activists, diplomats and some in the business world fear will jeopardize its semi-autonomous status and its role as a global financial hub.
She also said the USA called on the U.N.to demand China reverse course "and honor its worldwide legal commitments to this institution and to the Hong Kongpeople".
But Trump said China has replaced this promised formula of "one country, two systems" with "one country, one system", by unilaterally imposing control over Hong Kong in the name of protecting national security.
A spokesperson of North Korea's foreign ministry backed China's controversial security legislation for Hong Kong Saturday, calling it a "legitimate step" and voicing opposition to "outside interference".
"This is the product of a plot by the external force and its vassal forces that seek the division and disintegration of China by tarnishing the image of a socialist country and fomenting and escalating a social disorder", the spokesperson added.
What could losing United States "special status" mean for Hong Kong?
Authorities in Beijing and Hong Kong insist the legislation will target only a small number of "troublemakers" who threaten China's national security.
In a statement, she said: "If China imposes this law, we will explore options to allow British Nationals Overseas to apply for leave to stay in the United Kingdom, including a path to citizenship".
Referring to the security law, she told the BBC: "This is the latest in a series of attempts by China to start to erode the joint declaration which Britain co-signed with the Chinese government when we handed over Hong Kong, and protected its special status".
Protests are simmering again as Hong Kong emerges from its coronavirus shutdown.
Trump said his announcement would "affect the full range of agreements we have with Hong Kong", from the USA extradition treaty to export controls on dual-use technologies and more "with few exceptions".
At the same time, Trump announced that the US will be "terminating" its relationship with the World Health Organization (WHO), saying the group is unfairly biased towards China.
The Hong Kong government ― which has a long history of working ties with USA counterparts distinct from Beijing ― has yet to respond, although it warned on Thursday the move could be a double edged sword. He said he will direct the government to study the "differing practices" between Chinese and American companies in financial markets.
Trump also has to take into account the effect on the more than 1,300 USA firms that have offices in Hong Kong and provide about 100,000 jobs. In the past decade, the USA trade surplus with Hong Kong has been the biggest among all its trading partners, totalling $297 billion from 2009 to 2018.
But any move to deter students is unwelcome for U.S. universities, which rely increasingly on tuition from foreigners and have already been hit hard by the COVID-19 shutdown.
Donald Trump has unleashed his most scathing attack on China yet, accusing it of ripping off "the United States like no one has ever done before".
Trump has become less enthusiastic about the significance of the so-called phase one deal as the coronavirus pandemic devastates the USA economy, triggering concerns that he may seek to terminate the hard-fought accord.
Trump's edict will only impact a tiny percentage of the approximately 360,000 Chinese students in the US.