President Trump had previously been non-committal about whether he would sign the bill, saying he was “with” Hong Kong but also that President Xi was “an incredible guy”.
However, the bill had widespread congressional support, which meant that even if he vetoed it, lawmakers could potentially have voted to overturn his decision.
President Trump also signed a second bill, which bans the export of crowd-control munitions to the police in Hong Kong – including tear gas, rubber bullets and stun guns.
He said: “[The bills] are being enacted in the hope that leaders and representatives of China and Hong Kong will be able to amicably settle their differences, leading to long-term peace and prosperity for all.”
The bill was introduced in June in the early stages of the protests in Hong Kong, and was overwhelmingly approved by the House of Representatives last month.
It says: “Hong Kong is part of China but has a largely separate legal and economic system.
“The [annual review] shall assess whether China has eroded Hong Kong’s civil liberties and rule of law as protected by Hong Kong’s Basic Law.”
Among other things, Hong Kong’s special trading status means it is not affected by US sanctions or tariffs placed on the mainland.
The bill also says the US should allow Hong Kong residents to obtain US visas, even if they have been arrested for being part of non-violent protests.
Hong Kong’s protests started in June against a proposed law to allow extradition to mainland China but it has since transformed into a larger pro-democracy movement.
The protests have also seen increasingly violent clashes, with police being attacked, and officers firing live bullets.
The last week elections saw a landslide victory for the pro-democracy movement, with 17 of the 18 councils now controlled by pro-democracy councilors.
Pro-democracy campaigners hope they will be able to increase their representation on the council, which traditionally has some influence in choosing the city’s chief executive.
Pro-Beijing candidates are urging voters to support them in order to express frustration at the upheaval caused by continuous clashes between protesters and police.
Polls opened at 07:30 local time on November 24.
According to government figures, by 16.30 more than 2.1 million people had voted (52.14% of all registered voters) compared to 754,705 (24.18%) within the same timescale in the last such elections in 2015.
In total, 1.467 million people voted in the last poll. Only 3.1 million people were registered to vote in that election.
More than 1,000 candidates are running for 452 district council seats which, for the first time, are all being contested. A further 27 seats are allocated to representatives of rural districts.
Currently, pro-Beijing parties hold the majority of these seats.
Police were seen outside some polling stations and on the streets but correspondents said they kept a low profile.
Chief Executive Carrie Lam said after voting: “Facing the extremely challenging situation, I am pleased to say… we have a relatively calm and peaceful environment for (the) election today.”
Counting will start immediately after polls close at 22:30. Results are expected to start coming in before midnight.
The local councilor, Andrew Chiu Ka-yin, reportedly was attempting to prevent the attacker leaving the scene when the man bit off a section of his ear. Witnesses said the attacker was badly beaten by passersby who intervened, before police arrested the man.
The injured woman told the South China Morning Post that the attacker drew a knife after arguing with her sister and her husband, who were also injured.
According to the Hong Kong Free Press, the attacker was a Mandarin-speaking pro-Beijing supporter.
Hong Kong has experienced five months of sometimes violent demonstrations by pro-democracy activists, who first took to the streets to protest against a bill that would have allowed extradition to mainland China, but evolved into a broader revolt against the way Hong Kong is administered by Beijing.
The pro-democracy protests continued this weekend, days after a high-profile activist, Joshua Wong, was banned from standing in local elections.
Police fired tear gas into crowds of demonstrators in the eastern suburb of Taikoo Shing, home to the Cityplaza where the knife attack occurred.
Hong Kong has now seen 13 successive weeks of demonstrations.
The movement grew out of rallies against a controversial extradition bill – now suspended – which would have allowed criminal suspects to be sent to mainland China for trial.
It has since become a broader pro-democracy movement in which clashes have grown more violent.
During protests, crowds gathered by Prince Edward and Mong Kok stations in Hong Kong’s Kowloon neighborhood.
Police said in a tweet they had responded at both sites after reports of “radical protesters” assaulting citizens and damaging property.
In a statement, Hong Kong’s government also said some protesters had “committed arson and “hurled miscellaneous objects and iron railings” on to railway tracks, “completely disregarding the safety of other passengers”.
Forty people were subsequently arrested for unlawful assembly, criminal damage and the assault of police officers, police spokesperson Yolanda Yu told reporters.
However, several people complained of excessive force used by the authorities.
MTR, which operates the city’s subway line, told local media that three stations – Prince Edward, Mongkok and Kowloon Bay – had been closed as a result of the incident.
Protesters took to the streets in the Wan Chai district, many joining a Christian march, while others demonstrated in the Causeway Bay shopping district in the pouring rain. Many carried umbrellas and wore face masks.
Demonstrators took to the streets in the Wan Chai district, many joining a Christian march, while others protested in the Causeway Bay shopping district in the pouring rain. Many carried umbrellas and wore face masks.
On the 13th weekend of protests, demonstrators – chanting “stand with Hong Kong” and “fight for freedom” – gathered outside government offices, the local headquarters of China’s People’s Liberation Army and the city’s parliament, known as the Legislative Council.
In the Admiralty district, some demonstrators threw fire bombs towards officers. Earlier, protesters marched near the official residence of embattled leader Carrie Lam, who is the focal point of much of the anger.
Police had erected barriers around key buildings and road blocks, and fired tear gas and jets of blue-dyed water from the water cannon. The colored liquid is traditionally used to make it easier for police to identify protesters.
The recent demonstrations have been characterized as leaderless.
On August 30, police had appealed to members of the public to cut ties with “violent protesters” and had warned people not to take part in the banned march.
Police made a number of arrests on August 31.
During a 24-hour police crackdown, at least three activists – including prominent 23-year-old campaigner Joshua Wong – and three lawmakers were detained.
Joshua Wong, who first rose to prominence as the poster boy of a protest movement that swept Hong Kong in 2014, was released on bail after being charged over the protests which have rocked the territory since June.
Hong Kong is part of China, but enjoys “special freedoms”. Those are set to expire in 2047, and many in Hong Kong do not want to become “another Chinese city”.
Beijing has repeatedly condemned the protesters and described their actions as “close to terrorism”. The protests have frequently escalated into violence between police and activists, with injuries on both sides.
Activists are increasingly concerned that China might use military force to intervene.
On August 29, Beijing moved a new batch of troops into Hong Kong, a move Chinese state media described as a routine annual rotation.
Protesters initially gathered in Mong Kok, a Hong Kong district where violent clashes took place during pro-democracy protests in 2014.
A group of demonstrators briefly blocked access to the Cross Harbour Tunnel, causing traffic chaos, while others set up make-shift barricades on shopping streets.
As the demonstrations dragged into the night, protesters gathered outside the police station in Tsim Sha Tsui district. Officers then fired tear gas at the activists.
The South China Morning Post published a police statement saying the “radical” group had set fires nearby and had thrown bricks into the building.
The march comes after a group of civil servants – ordered to be politically neutral – joined demonstrations in their thousands on August 2.
The rally followed the publication of an anonymous letter on Facebook complaining about “extreme oppression” and listing five key demands – the complete withdrawal of the extradition bill; waiving charges against those arrested; an end to descriptions of protests as “rioting”; an independent inquiry into the unrest; and resuming political reforms.
Supporters of Hong Kong’s police force also gathered earlier for a rally in Victoria Park.
Some unions and organizations have reportedly already agreed to take part in the strike planned for August 5. There are also further demonstrations planned for August 4.
Tear gas has been fired by Hong Kong riot police at an unauthorized protest held by tens of thousands of people to condemn an attack by armed masked men last week.
As a small group of protesters refused to disperse in the northern district of Yuen Long, police fired rubber bullets.
The protest took place where pro-democracy protesters had been attacked by suspected triad gang members.
Police have been accused of turning a blind eye and colluding with the attackers, claims they deny.
There were seven weeks of anti-government and pro-democracy protests in Hong Kong sparked by a controversial bill that would have enabled extraditions to mainland China.
The government has since halted the legislation but protesters have demanded its complete withdrawal, as well as an inquiry into police violence, democratic reform, and that Hong Kong’s leader Carrie Lam resign.
The July 27 rally had been banned by the police, a highly unusual move in the territory, where protests are usually allowed.
Police say they refused permission because they feared violent clashes between protesters and residents.
The march was planned as a response to last Sunday’s attack, in which about 100 men descended on Yuen Long’s metro station, beating protesters – as well as passersby and journalists – with wooden and metal sticks.
The attack left 45 people injured and was widely blamed on triad gang members. They appeared to target those wearing black, the color people had been told to wear for the protest.
Triads are known to be active in Yuen Long – located in a rural northern district in Hong Kong, near mainland China – and many local villagers have also expressed opposition to the pro-democracy protests.
Tens of thousands defied the police ban and approached Yuen Long on July 27, marching down some of the main roads.
Police observed and filmed the start of the protest, and riot police could be seen on standby.
They said some protesters were holding iron poles and shields, and “even removing fences from roads”.
Some protesters also surrounded and vandalized a police vehicle, “causing danger to the life of the police officers on board”, they said.
Shortly after 17:00 local time, police began firing several rounds of tear gas in an attempt to disperse the crowd.
The protesters – most wearing masks and hard hats – threw projectiles and swore at police – but also parted to allow ambulances to go through.
Later in the evening, in an attempt to clear several hundred demonstrators, police fired rubber bullets, injuring at least nine people, according to the AFP news agency.
Protesters have been demanding an independent inquiry into police violence, saying police used excessive force in several anti-extradition bill and pro-democracy protests.
Demonstrators and pro-democracy legislators have alleged that the authorities – including the police and pro-government legislators – had advance knowledge of the attack.
Police say suggestions that they colluded with criminal gangs were a “smear”, and that 12 people have so far been arrested, including nine men with links to triads.
There have also been growing tensions between protesters and pro-Beijing groups.
Earlier this week, pro-Beijing legislator Junius Ho’s office was ransacked, and his parents’ graves were vandalized.
Junius Ho had come under criticism after video footage showed him shaking hands with white-shirted men on July 27 shortly before the attacks.
He said he did not know about the attack, but defended the men, saying they were simply “defending their home and people”.