He is generally regarded as the driving force behind the attempted democratization of Czech political life in 1968 that became known as the Prague Spring. At this time he and other liberal members of the government made plans for a new constitution as well as legislation for civil liberties and began to pursue a foreign policy independent of the Soviet Union. In response, Warsaw Pact forces invaded Czechoslovakia in August 1968 and Dubček was removed from office the following year. After the abandonment of Communism at the end of 1989 he returned to public life and was elected speaker of the Federal Assembly in a new democratic regime.