What China's new security law means for Hong Kong

Beijing has imposed sweeping new national security legislation on Hong Kong, criminalising 'secession, subversion, terrorism and collusion with foreign forces'. Critics fear the law will enable a crackdown on protest and dissent as China seeks to exert new levels of control over the semi-autonomous territory. The Guardian's Beijing bureau chief, Lily Kuo, explains what this means for the city after a year of unrest