Riot police stand in line as anti-national security law protesters march at the anniversary of Hong Kong's handover to China from Britain in Hong Kong, China July 1, 2020. Hong Kong police fired water cannon on Wednesday to break up the first protest since China introduced sweeping security legislation and they made their first arrests under it, warning of punishment for advocating secession or subversion. REUTERS/Tyrone Siu

Riot police disperse anti-national security law protesters during a march at the anniversary of Hong Kong's handover to China from Britain in Hong Kong, China July 1, 2020. Beijing on Tuesday unveiled the details of the much-anticipated law after weeks of uncertainty, pushing China's freest city and one of the world's most glittering financial hubs onto a more authoritarian path. REUTERS/Tyrone Siu

Riot police stop and search people during a march against national security law at the anniversary of Hong Kong's handover to China from Britain in Hong Kong, China July 1, 2020. As thousands of protesters gathered downtown for an annual rally marking the anniversary of the former British colony's handover to China in 1997, riot police used pepper spray to make arrests, while shops and one metro station closed. REUTERS/Tyrone Siu

Riot police stop and search people during a march against national security law at the anniversary of Hong Kong's handover to China from Britain in Hong Kong, China July 1, 2020. As thousands of protesters gathered downtown for an annual rally marking the anniversary of the former British colony's handover to China in 1997, riot police used pepper spray to make arrests, while shops and one metro station closed. REUTERS/Tyrone Siu

Anti-national security law protesters march at the anniversary of Hong Kong's handover to China from Britain in Hong Kong, China July 1, 2020. As thousands of protesters gathered downtown for an annual rally marking the anniversary of the former British colony's handover to China in 1997, riot police used pepper spray to make arrests, while shops and one metro station closed. REUTERS/Tyrone Siu

Anti-national security law protesters march at the anniversary of Hong Kong's handover to China from Britain in Hong Kong, China July 1, 2020. As thousands of protesters gathered downtown for an annual rally marking the anniversary of the former British colony's handover to China in 1997, riot police used pepper spray to make arrests, while shops and one metro station closed. REUTERS/Tyrone Siu