Ronald Reagan entered the White House determined to offer a direct challenge to the Soviets. Reagan and Secretary of State George Shultz believed that détente would become feasible only after the United States achieved military supremacy over the Soviet Union. Reagan also took strong measures to fight communism around the globe, from Central America to the Middle East. Yet military superiority alone would not defeat the Soviet Union. A shift of leadership within the USSR, as well as a worldwide protest movement for nuclear disarmament, helped bring an end to the Cold War and prepare the way for the dissolution of the Soviet empire.