A Chinese government-backed think tank has accused the U.S. and other Western governments of using social networking sites like Facebook  to spur political unrest and called for stepped-up scrutiny of the wildly popular sites.

As China’s online population — the world’s largest — surges past the 400 million mark, its Communist government is growing increasingly sensitive to any online threats to its authority. Although Beijing operates an extensive system of monitoring and censorship to block material deemed subversive, the Internet is still the most open and lively forum for discussion in a society where traditional media are controlled by the state.