The Czechoslovak Communist Party began an ambitious reform agenda under Alexander Dubček. The plan to limit central control and make the economy more independent of the party threatened bedrock beliefs. On 20 August 1968, Soviet leader Leonid Brezhnev ordered a massive military invasion by Warsaw Pact forces that destroyed the threat of internal liberalization. At the same time, the Soviets threatened retaliation against the British-French-Israeli invasion of Egypt. The upshot was a collapse of any tendency toward détente and the resignations of more intellectuals from communist parties in the West.