The Communist Party mouthpiece People's Daily published a rallying cry for stability yesterday.
In a front-page editorial, the paper called on the people to back the leadership to curb attempts by "hostile forces to infiltrate, subvert and split" China.
"We must resolutely trust the leadership of the party's Central Committee even more, and consciously safeguard the authority of the Central Committee even more," it said.
Stability has been the watchword as authorities braced for trouble in the run-up to June 4.
Actions that sabotaged stability and political unity should be "nipped in the bud", the paper said.
The paper defended the 1989 crackdown, saying the decisive move was "very timely and very necessary".
The crackdown "forcefully protected our nation's independence, dignity, security and stability, and guaranteed the continued healthy development of reform and opening up and economic construction", it said.
The anniversary has prompted an apparently coordinated closure of Internet chat rooms. One of the most popular said on Tuesday it was closing for 10 days.
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