NATO, the North Atlantic Treaty Organization, was created in 1949 as a post-WWII effort to create a defense alliance to deter Soviet expansion into Western Europe. When the Cold War began, NATO served as the primary form of Soviet deterrence for the West, utilizing the strategy of containment of communism. The Soviets retaliated by forming the Warsaw Pact including Eastern European nations to create their own alliance, thickening the Cold War plot. The Cold War ended with no actual fighting, slightly easing US-Russia tensions, but maintaining a stark divide between Western and Eastern Europe. In the 1980s, Mikhail Gorbachev was rising through the ranks of the Russian communist party, becoming Soviet leader and implementing reform initiatives to rebuild the USSR and further align the nation with Western advancements. Despite these efforts, the Soviet system was collapsing.