 Cleared for travel to Eastern Bloc countries, in 1966 he was part of a delegation visiting East Germany, and in 1969 and 1974 visited Bulgaria.In August 1968 the Soviet Union led an invasion of Czechoslovakia to put an end to the Prague Spring, a period of political liberalization in the Marxist–Leninist country.Although Gorbachev later stated that he had had private concerns about the invasion, he publicly supported it.