He was Khrushchev's successor who quieted people who spoke out against the government, otherwise known as dissidents. Brezhnev invested in a huge military buildup. In the Brezhnev Doctrine, he asserted that the Soviet Union had a right to intervene militarily in any Warsaw Pact nation. He also pursued detente and disarmament with the United States. The Soviets invaded Afghanistan to ensure Soviet influence in that neighboring nation, which ended in 1979.