CNN's Ivan Watson reports on the buildup that has led to protesters clashing with riot police in Hong Kong.

Protesters stage a sit-in rally at the arrival hall of the Hong Kong International Airport in Hong Kong, Tuesday, Aug. 13, 2019. Protesters clogged the departure area at Hong Kong's reopened airport Tuesday, a day after they forced one of the world's busiest transport hubs to shut down entirely amid their calls for an independent inquiry into alleged police abuse.

(AP Photo/Vincent Thian)