Czechoslovak government-in-exile
After World War II, the Czechoslovak government-in-exile returned. Normal relations continued until 1948, when the communists seized power and relations froze rapidly. The Soviet invasion of Czechoslovakia in August 1968 further complicated U.S.-Czechoslovak relations. The United States referred the matter to the United Nations Security Council as a violation of the United Nations Charter, but no action was taken against the Soviets.