China's foreign ministry on Wednesday criticized the U.S. after the Senate unanimously passed a bill supporting Hong Kong protesters.
The "Hong Kong Human Rights and Democracy Act" interferes in China's domestic affairs, said foreign ministry spokesperson Geng Shuang, according to an online statement in Chinese.
China "strongly condemns and resolutely opposes" the act of interference, Geng said hours after the bill was passed.
That bill now proceeds to the House, which already approved its own version of the bill in October. The two chambers of Congress have to work out differences between their bills before it can be sent to President Donald Trump.
The upper house of Congress also passed a separate bill banning certain munition exports to the Hong Kong police.
Hong Kong is a former British colony and returned to Chinese rule in 1997. As a special administrative region of China, the city operates under a "one country, two systems" structure, which grants its residents legal and economic freedoms that citizens in mainland China do not have.
China's foreign ministry said in a statement that it has made stern representations to a U.S. embassy official in Beijing on Wednesday after the proposed legislation was passed in the Senate.
It said Vice Foreign Minister Ma Zhaoxu summoned William Klein, the U.S. embassy's minister counselor for political affairs. Ma told Klein that Hong Kong's affairs are the internal affairs of China, and demanded that the U.S. stop interfering.
Hong Kong has been crippled by widespread demonstrations since early June. What started out as protests against an extradition bill has morphed into broader anti-government demonstrations, including a wider range of demands such as greater democracy and universal suffrage.
Reuters reported that fewer than 100 anti-government protectors are now trapped in a Hong Kong university in a standoff with the police amid increasingly violent clashes in the last week.
The Hong Kong government on Wednesday "expressed deep regret" over the passage of the proposed act.
"The 'Hong Kong Human Rights and Democracy Act' and the other act on Hong Kong are unnecessary and unwarranted. They will also harm the relations and common interests between Hong Kong and the US," a government spokesman said in a statement from the Hong Kong government.
"Since the return to the Motherland, the HKSAR (Hong Kong Special Administrative Region) has been exercising 'Hong Kong people administering Hong Kong' and a high degree of autonomy in strict accordance with the Basic Law of the Hong Kong Special Administrative Region of the People's Republic of China. The 'one country, two systems' principle has been fully and successfully implemented," added the spokesman.
Despite the clash over the bill, the U.S. and China are still likely to reach a "phase one" trade deal, said Robert Daly, director of the Wilson Center's Kissinger Institute on China and the United States.
"If there is a phase one trade deal is in the offing, it's almost certainly going to be a deal largely on Beijing's terms; something that Beijing will want — purchases and promises, not a deal reckoning on the structural process," Daly told CNBC on Wednesday. "China would want that deal even if it felt insulted over Hong Kong."
The U.S. is unlikely to withdraw Hong Kong's special trading status for now, Daly said.
Under the U.S.-Hong Kong Policy Act of 1992, Washington treats Hong Kong as a separate region from mainland China even after the former British colony transferred to Chinese rule in 1997. That includes treating Hong Kong as a separate customs territory.
Therefore, Hong Kong exports to the U.S. are not subject to the tariffs that the Trump administration has imposed on goods from mainland China.
"I don't think they would directly withdraw that relationship unless China went in with armed force either through the PLA (People's Liberation Army) or through the People's Armed Police," Daly said at the Morgan Stanley Asia Pacific Summit.
The Hong Kong Human Rights and Democracy Act still has to be reconciled and signed into the law by the U.S. president — a process that could be "slow walked," said Daly.
Regarding the PLA's clean-up activity on the streets of Hong Kong last week, Daly said that was an "interim step" that Beijing was taking to get people used to seeing the PLA on the streets of Hong Kong "although seeing them in a relatively benign light of young men and women clearing bricks."
"This is also signalling to the people of China to see the People's Liberation Army out there as virtuous, as constructive as opposed to the chaos and the protesters in Hong Kong itself," said Daly.
Aside from the political signalling within China, it would also be an "interim step to further involvement of either the People's Armed Police or PLA," said Daly.
Both Beijing and Hong Kong are "scrambling" over what to do about the situation in the city, said Ben Bland, director at Australian think tank Lowy Institute.
"No one really expected we would see this level of defiance, of violence, but also of unity from the supporters of democracy in Hong Kong," he said. "I think it has caught the Hong Kong government off-guard. It has caught Beijing off-guard. It has caught the rest of the world off-guard."
But expect more Beijing oversight in Hong Kong, said Bland.
"The one thing that we can expect and which they have indicated is that they are going to be squeezing Hong Kong harder on so many fronts more prosecutions, more assertive action from the police, and in fact more direct control over Hong Kong from the authorities in Beijing," Bland said.
On Tuesday, Beijing said Hong Kong courts have no power to rule on the constitutionality of legislation under the city's Basic Law.
That came just a day after the special administrative region's High Court ruled that a ban on the wearing of face masks during public demonstrations was unconstitutional.
"I think they want a Hong Kong that's loyal and quiet and does what it's told and as to how they get there that depends on how Hong Kongers react and so far they've really been digging their heels in," Bland said.