A massive police presence ringed China’s Tiananmen Square today, the 20th anniversary of the bloody crackdown on pro-democracy activists, as the government continued an overwhelming drive to muzzle dissent and block commemorations.

Fifteen years after the bloodshed, the exiled student leaders of China’s 1989 pro-democracy protests are settled abroad as academics and entrepreneurs. But they nurture one wish above all – to come home to a new system.

Chinese activists have been forced to leave their homes and placed under watch by authorities two days before the 25th anniversary of the Tiananmen Square crackdown on pro-democracy demonstrators, a human rights group said today.