The USSR invaded Czechoslovakia in 1968 and crushed the 'Prague Spring'.
In 1968, The Czechoslovakia goverment, headed by Alexander Dubcek, planned to implement reforms aimed at granting greater political freedom, economic policies that would ensure less state control, more reliance on free market economics and Dubcek insisted on greater freedom from Russian and Soviet domination. Alexander Dubcek was no revolutionary, or even anti Communist or against the USSR in anyway. In fact he was quite the opposite. Dubcek, with his background and training in Russia, was seen by the USSR as a safe pair of hands. “Our Sasha”, as he was known back in Moscow. He became the new First Secretary of the Communist Party of Czechoslovakia on 5 January 1968, with the complete and utter support of Moscow. However once he took power, he did try to change the more harsher Stalinist aspects in Czechoslvakia, and to give the Communist/Socialist regime a "human face", which would be less rigid and authoritarian and more open and tolerant. He sought to win popular support for the Communist government by eliminating its worst, most repressive features, allowing greater freedom of expression and tolerating political and social organizations not under Communist control.
Alexander Dubcek. The sudden atmosphere of freedom that Dubcek was encouraging took root, and Czech citizens embraced and celebrated the new tolerance for free exchange of ideas and open discussion in what came to be known as the “Prague Spring.” The USSR response to Dubcek's reforms and the general atmosphere that prevailed in Czechoslovakia in those years, to what would later become known as the “Prague Spring”, was to invade Czechoslovakia. On the night of August 20, 1968, more than 250,000 Warsaw Pact troops crossed into Czechoslovakia and headed for the capital city of Prague. In just over a day, the entire country was occupied; within a week nearly three-quarters of a million foreign troops were in Czechoslovakia.
Soviet troops occupying Czechoslovakia. Anti-Soviet riots broke out in Prague, but these were viciously crushed and thousands of Czechs fled the country. The United States and NATO turned a blind eye to the evolving situation in Czechoslovakia. The United States made it clear that it would not intervene on behalf of the Prague Spring, giving the USSR a free hand to do as it pleased. It took the USSR a full eight months to quell the inspired non-violent resistance of the Czech and Slovak population, in contrast to the original Soviet military's estimate of four days. The Soviet military presence in Czechoslovakia would last until 1991. Even though Czechoslovakia's spirit of rebellion and reform were crushd by the USSR, they were not destroyed, and they would make a comeback in 1989 with the "The Velvet Revolution", which would result in the collapse of communist regime in Czechoslovakia.