Hong Kong authorities on Monday strengthened a crackdown on 16 overseas-based activists who were previously targeted by bounties on suspicion of endangering national security, implementing measures that include banning financial support to them and canceling passports for most of them. The activists were among 19 people who were targeted with arrest warrants in July for alleged roles in Hong Kong Parliament, a group the police called a subversive organization abroad. Three of the original 19 activists were already targeted by similar measures last year.