The worst thing about the Tiananmen square massacre is that it was totally effective. Movements for democractic reform ended in China, and through out the communist world. They have not returned. Chinese youth have become depoliticized. The protestors still remain in prison.
The lesson of history is clear. Iran is already threatening to "crack down" on the protestors. Eventually, they'll make good on those threats. Its going to be ugly, and as long that the state can prevent local media from accurately reporting about the events, its going to be the end of the movement for liberalization in Iran.
The problem with public street demonstrations is that they are only effective if the people being protested care about the opinions of the demonstrators or about the opinions of people who are influenced by the demonstrators. That is rarely the case.
The Party leadership expelled Zhao Ziyang from the Politburo Standing Committee of the Communist Party of China (PSC), because he opposed martial law, and Zhao remained under house arrest until his death. Hu Qili, the other member of the PSC who opposed the martial law but abstained from voting, was also removed from the committee. He was, however, able to retain his party membership, and after "changing his opinion", was reassigned as deputy minister of Machine-Building and Electronics Industry. Another reform-minded Chinese leader, Wan Li, was also put under house arrest immediately after he stepped out of an airplane at Beijing Capital International Airport upon returning from his shortened trip abroad, with the official excuse of "health reasons." When Wan Li was released from his house arrest after he finally "changed his opinion" he, like Qiao Shi, was transferred to a different position with equal rank but mostly ceremonial role. Several Chinese ambassadors abroad claimed political asylum....
State media mostly gave reports sympathetic to the students in the immediate aftermath. As a result, those responsible were all later removed. Two news anchors who reported this event on 4 June in the daily 1900 hours (7:00 pm) news report on China Central Television were fired because they showed their sad emotions...
Several editors were arrested, with Wu Xuecan, who organised the publication of an unauthorised Extra edition, sentenced to four years' imprisonment.
Rob Gifford, a National Public Radio journalist, said that much of the political freedoms and debate that occurred post-Mao and pre-Tiananmen ended after Tiananmen.... Gifford added that people born after 1970 had "near-complete depoliticization" while older intellectuals no longer focus on political change and instead focus on economic reform...
The Tiananmen square protests dampened the growing concept of political liberalization in communist countries that was popular in the late 1980s; as a result, many democratic reforms that were proposed during the 1980s were swept under the carpet. Although there has been an increase in personal freedom since then, discussions on structural changes to the PRC government and the role of the Communist Party of China remain largely taboo.