Congress overwhelmingly passed legislation this week supporting the protests in Hong Kong, which have raged for nearly half a year. The bill, known as the “Hong Kong Human Rights and Democracy Act,” will head to President Donald Trump’s desk to review within the coming days.

Protesters would herald the passage of the act as a victory, believing it could pressure the Hong Kong government into acceding to their political demands. But the policy would likely further strain the U.S.-China relationship, which is already hampered by a bruising trade war. Chinese officials have ominously warned of harsh countermeasures against the U.S. if the bill becomes law.

As the act awaits Trump’s decision, here’s what to know about it.

What is the “Hong Kong Human Rights and Democracy Act”?

The legislation aims to safeguard Hong Kong’s civil rights and freedoms by linking the former British Colony’s special trade status to its continued autonomy from Beijing,

Introduced by Rep. Jim McGovern, Sen. Marco Rubio and Rep. Chris Smith in June, when the pro-democracy protests began, the act passed both the Senate and House this week after gaining rare bipartisan support.

If passed, the State Department would have to annually assess whether Hong Kong retains sufficient political autonomy to continue to qualify for favorable trading terms with the U.S. Any officials deemed responsible for violating human rights could face sanctions and visa restrictions.

Of concern is the “high degree of autonomy” that Beijing promised Hong Kong when the entrepôt retroceded to Chinese sovereignty in 1997. Fears over how China’s encroachment will transform the city helped fuel demonstrations that have plunged the Asian financial capital into escalating violence for the past five months.

The protesters have appealed to the international community for support in their fight with Beijing. At rallies for the democracy act staged around the world, supporters have waived U.S. flags and called upon Trump to “save” Hong Kong.

Activist Joshua Wong traveled to Washington in September to testify before Congress. In an interview with TIME after his trip, he said the passage of the act would start “a new chapter of bipartisan consensus on a tougher approach to Hong Kong’s democratization.”

Read more: Now Is the Time for the U.S. to Stand With Hong Kong

What happens now?

After the bill swept through the House Wednesday, it went to Trump. Typically, Presidents have 10 days to sign approved legislation, but Trump has some extra time over the Thanksgiving holiday while Congress is adjourned.

Marco Rubio, one of the act’s sponsors, told CNBC that it is his “understanding” that the legislation will be signed. “We will not stand idly by as Beijing undermines” Hong Kong’s autonomy, he said from the Senate floor Tuesday.

But the bill comes amid a trade war stalemate and a sensitive Dec. 15 deadline to decide whether to renew a major set of tariffs on Chinese goods.

While both Republicans and Democrats see the act as a key component of the U.S.’s promotion of democracy and human rights abroad, Trump’s commitment to such advocacy has been questioned. On Hong Kong, he has mostly avoided commenting.

If Trump chooses to exercise his veto powers, he can still be overridden by a two-thirds vote in both the Senate and the House.

How has Beijing responded?

Beijing has denounced the legislation as an intrusion on its sovereignty. Foreign Ministry Spokesperson Geng Shuang said the act “neglects facts and truth” and warned China would “have to take strong countermeasures.”

Communist mouthpiece Global Times said Wednesday the policy should be renamed the “Support Hong Kong Violence Act” as it has “overtly taken sides with rioters who are destroying the rule of law.”

Why is Hong Kong’s trading status so important?

Hong Kong was granted special trade status under the 1992 United States-Hong Kong Policy Act, which says the city should continue to be treated as a “separate territory” from the Chinese mainland “in economic and trade matters.”

The status has meant that as trade tensions between the U.S. and China escalate, Hong Kong’s exports are exempt from U.S. tariffs and other protectionist measures on Chinese goods.

But experts warn that any termination of Hong Kong’s special status would hinder not just the city and Beijing, but also U.S. business interests. According to the State Department, more than 1,300 U.S. companies operate in Hong Kong, benefiting from proximity to China, as well as the city’s independent judiciary and rule of law.

For now, the act is mostly symbolic, since any adjustments to the trade status hinge the conclusions of an annual review, says Willy Lam, an adjunct professor at the Chinese University of Hong Kong. “For the protestors and the pro-democracy camp, this is a fairly important piece of moral support coming from the U.S.,” he says.

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