Check, 08/21/68: An unidentified man comments on the Soviet invasion of Czechoslovakia. On the night of August 20, approximately 200,000 communist troops from five Warsaw Pact nations–the Soviet Union, Bulgaria, Hungary, East Germany, and Poland–invaded Czechoslovakia. The invading force detained government leaders and transported them to Moscow, as well as seized control of Prague television and radio stations. More than 120 Czechoslovakian civilians were killed, most of them protesters. The attack was intended to crush the democratic reforms of the "Prague Spring," a brief period of liberalization in the otherwise communist country. On August 27, Czechoslovakia's First Secretary Alexander Dubček returned to Prague and announced he had agreed to curtail his progressive reforms. Dubček was forced to resign in April 1969 following anti-Soviet riots.