The U.S. Senate passed a bill to punish those who back China's efforts to restrict Hong Kong's autonomy on Thursday (June 25), legislation that was unanimously approved by lawmakers.
The measure pushes back at Beijing's new security law for the territory, which has alarmed both foreign governments and pro-democracy activists.
Beijing says it's designed to prohibit secession, subversion, and external interference in Hong Kong.
Critics say it will crush the city's much coveted freedoms.
The U.S. bill would slap mandatory sanctions on people or companies who back Beijing's efforts, including banks which do business with anyone found to be backing a Hong Kong crackdown.
It could potentially cut these companies off from American counterparts - and limit their access to U.S. dollar transactions.
The Hong Kong Autonomy Act must now pass the House and the White House to be signed into law.
Meanwhile Hong Kong is bracing for the security law.
It's already hit attendance and enthusiasm for Hong Kong's pro-democracy protests.
A poll conducted for Reuters shows support for the Hong Kong protests has slipped from 58 percent in March to a slim majority of 51 percent.
A draft of the new law has yet to be finalised, and it remains unclear what activities would constitute crimes -- and what the punishment would be.
Hong Kong and Beijing authorities have repeatedly insisted rights and freedoms will be preserved under the bill, and that it will only target a small number of quote "troublemakers."
However, the law has already prompted U.S. President Donald Trump to announce -- he will begin eliminating special economic treatment for the city.
Some key features of the bill have already been released.
Communist Party central authorities will have overarching powers over the law's enforcement, including final say on how its interpreted