Police are keeping a close watch on students, intellectuals and the grave of former Communist Party leader Hu Yaobang to prevent public commemorations of the tenth anniversary of the start of the Tiananmen Square democracy movement protests. Hu Yaobang was ousted for being too liberal shortly before his death in April 1989. This triggered the student protests that brought over a million to Beijing's Tiananmen Square and which ended seven weeks later with tanks and troops.