Why did Soviet forces invade Czechoslovakia in August 1968?

In August 1968, Soviet-led forces invaded Czechoslovakia to suppress the Prague Spring, a period of political and economic liberalization initiated by the country's leader, Alexander Dubček.12

The Soviet Union and its Warsaw Pact allies viewed these reforms—which included the removal of censorship, the guarantee of civil rights, and the pursuit of "socialism with a human face"—as a dangerous counterrevolution that threatened the stability of the socialist bloc. Moscow feared that Czechoslovakia’s move toward greater freedom of expression and potential shifts in international relations would damage the fundamental interests of other socialist countries.3124

This intervention was justified by the Brezhnev Doctrine, a foreign policy stance asserting that the Soviet Union had the right and duty to intervene in any socialist country where the established order was under threat. Following the invasion, the reformist government was forced to accept the Moscow Protocol, which effectively ended the liberalization movement and initiated a period of "normalization" under hard-line leadership.125