Fred Halliday in openDemocracy:

The most dramatic events of 1968, and the ones with the greatest long-run consequences were not, however, in either Europe and north America or in the “third world” – but in the “second” (that is, communist) world. Two events here in particular – the Soviet invasion of Czechoslovakia in August 1968 which crushed the liberalising “Prague spring” under Alexander Dubcek, and the apogee of China’s cultural revolution in 1967-68 – signalled the brutal imposition of authoritarian and coercive bureaucratic communism.

In Prague, Moscow and Beijing – a world away from the liberal and culturally experimental world of Paris or Berkeley – it was not the emancipatory imagination but the cold calculation of party and state that was “seizing power”. Yet in the longer run the counter-cyclical reinforcement of hardline communist rule in its two major centres proved less durable than appeared likely at the time.

Indeed, the repression of 1968 contained the seeds of the demise of the regimes that deployed it. In Europe, the decision by Leonid Brezhnev and his associates to invade Czechoslovakia in effect killed what were already the last, threadbare hopes that a progressive evolution of communist societies was yet possible. The casualties included the next generation of intra-party reformers, who thus had few reserves of loyalty or enthusiasm to call on beyond the party nomenklatura – and who were challenged by dissidents now hardened by experience to contemplate only communism’s demise rather than its reform.