China's ruling Communist Party unleashed a controversial national security law for Hong Kong, a move seen as a major blow to the city's freedoms.
The law to ban "betrayal, secession, sedition and subversion" could bypass Hong Kong lawmakers.
Critics say China is breaking its promise to allow Hong Kong's freedoms not to be seen elsewhere in China.
It is likely to fuel public anger and may even trigger new protests and demands for democratic reforms.
The plan was submitted to the annual National People's Congress, which largely makes decisions about stamps already taken by the communist leadership, but it is still the most important political event of the year.
Hong Kong should always have introduced these laws after it was handed over to Chinese rule in 1997.
This has never been possible and, following last year's wave of continuous and violent protests, Beijing is now trying to force them.
Beijing believes that "legal and vigorous measures" should be taken to "prevent, stop and punish" these protests in the future.
What's in the proposed Beijing law?
The "draft decision" – as it was known before the NPC's approval – was explained by Wang Chen, vice chairman of the NPC Standing Committee.
It consists of an introduction and seven articles. Article 4 may be the most controversial.
This article says that Hong Kong "must improve" national security, before adding: "When necessary, relevant national security organs of the Central People's Government will establish agencies in Hong Kong to fulfill the relevant duties of safeguarding national security in accordance with the law".
China could essentially put that law into Annex III to the Basic Law, which covers national laws that must be implemented in Hong Kong – by law or decree.
China's Prime Minister Li Keqiang spoke at the congress and spoke about the economic impact of the coronavirus,
In Hong Kong (and also in Macau), he made the following reference: "We will establish sound legal systems and enforcement mechanisms to safeguard national security in the two special administrative regions.
What do opponents say are the dangers?
Hong Kong is what is known as a "special administrative region" in China.
He has observed a "one country, two systems" policy since Britain returned sovereignty in 1997, which allowed certain freedoms that the rest of China does not have.
Pro-democracy activists fear that China, enforcing the law, could mean "the end of Hong Kong" – that is, the effective end of its autonomy and freedoms.
Last year's mass protests in Hong Kong were triggered by a bill that would allow extraditions to mainland China.
The project was paused and withdrawn – but the protests continued until the virus outbreak later in the year.
The U.S. also contributed, with President Trump saying the U.S. would react strongly if it passed – without giving details.
It is currently considering the possibility of extending Hong Kong's preferential trade and investment privileges.
Why is China doing this?
Wang said the security risks had become "increasingly noticeable" – a reference to last year's protests.
"Considering the situation in Hong Kong today, efforts should be made at the state level to establish and improve the legal system and enforcement mechanisms," he said in state media.
Beijing may also fear the September elections for the Hong Kong legislature.
If last year's success for pro-democracy parties in the district elections is repeated, government projects could be blocked.
What is the legal situation in Hong Kong?
Hong Kong was under British control for more than 150 years until 1997.
The British and Chinese governments signed a treaty – the Sino-British Joint Declaration – which agreed that Hong Kong would have "a high degree of autonomy, except in foreign and defense affairs", for 50 years.
This was enshrined in the Basic Law, which ends in 2047.
- What is Basic Law and how does it work?
- Why are there protests in Hong Kong? All the context you need
As a result, Hong Kong's own legal system, borders and rights – including freedom of assembly and freedom of expression – are protected.
But Beijing has the ability to veto any change in the political system and, for example, has ruled out the direct election of the chief executive.