Leonid Brezhnev was the General Secretary of the Communist Party of the Soviet Union from 1964 to 1982. He ordered the invasion of Czechoslovakia in 1968 to crush the Prague Spring, a period of political liberalization in the country.

Alexander Dubček was the First Secretary of the Communist Party of Czechoslovakia from 1968 to 1969. He was ousted from power after the Soviet invasion of Czechoslovakia and replaced by Gustav Husak.

The Prague Spring was a period of political liberalization in Czechoslovakia that began in January 1968. It was crushed by the Soviet invasion in August 1968.

The Prague Spring aimed to introduce democratic reforms, increase economic freedom, and promote cultural liberalization in Czechoslovakia.

The Soviet Union justified its invasion of Czechoslovakia by claiming that it was necessary to protect its national security, prevent a counter-revolution, and uphold the socialist order.

The Soviet invasion of Czechoslovakia was met with widespread condemnation from the international community, including from many Western countries and the United Nations.

The Prague Spring increased tensions between the Soviet Union and the West, as it demonstrated the Soviet Union's willingness to use military force to suppress dissent in its satellite states.

The Prague Spring led to the collapse of communism in Czechoslovakia in 1989, but it also led to a period of economic stagnation and political repression in the country.

The Prague Spring is seen as a complex event with both positive and negative aspects. It is seen as a symbol of hope and resistance against authoritarianism, but it is also seen as a reminder of the dangers of communism and the importance of democracy.

Yugoslavia was not a member of the Warsaw Pact. It was a socialist country, but it was not aligned with the Soviet Union and pursued a policy of non-alignment.

Václav Havel was a leading figure in the Prague Spring and later became the first president of the Czech Republic after the collapse of communism.

The Brezhnev Doctrine was a Soviet doctrine that justified the invasion of Czechoslovakia in 1968. It stated that the Soviet Union had the right to intervene in the affairs of its satellite states to protect socialism.

Amnesty International was founded in 1961, but its membership and activism grew significantly after the Soviet invasion of Czechoslovakia in 1968.

Charter 77 was a Czechoslovak underground organization that was formed in 1977 to protest the government's human rights abuses.

Miloš Forman was a Czechoslovak film director who made the documentary film "The Unbearable Lightness of Being" in 1988.