Three key organizers of a public commemoration have been sentenced to prison for inciting subversion. The commemoration marked the 1989 Tiananmen Square massacre. The organizers' imprisonment is part of a national security crackdown that has been ongoing for years.

The trio were key figures in a group that organized an annual vigil to remember the victims of the massacre. The event commemorated the moments when tanks were sent in to quell peaceful democracy protests in Beijing's Tiananmen Square.

Further details about the sentencing and the crackdown are available from the source, including the context and implications of the imprisonment.