In 1997, the United Kingdom returned Hong Kong, which it had governed for 99 years under a lease extorted from the Qing Dynasty, back to the People’s Republic of China. At the time, the PRC promised to preserve the political autonomy and freedoms the city had enjoyed under the British until 2047. The national-security law and the crackdown it initiated marked the breaking of that promise.
Beijing’s move to exert increased control over the city reflects several factors, first and foremost among them the rise of Xi Jinping.