During the opening stages of World War II, the Soviet Union laid the foundation for the Eastern Bloc by invading and then annexing several countries as Soviet Socialist Republics , by agreement with Nazi Germany in the Molotov–Ribbentrop Pact . These included eastern Poland (incorporated into two different SSRs ),  Latvia (which became the Latvian SSR ),   Estonia (which became the Estonian SSR ),   Lithuania (which became the Lithuanian SSR ),   part of eastern Finland (which became the Karelo-Finnish SSR ) and eastern Romania (which became the Moldavian SSR ).  
Even as Reagan fought communism in Central America, however, the Soviet Union was disintegrating. In response to severe economic problems and growing political ferment in the USSR, Premier Mikhail Gorbachev (1931-) took office in 1985 and introduced two policies that redefined Russia’s relationship to the rest of the world: “glasnost,” or political openness, and “perestroika,” or economic reform. Soviet influence in Eastern Europe waned. In 1989, every other communist state in the region replaced its government with a noncommunist one. In November of that year, the Berlin Wall–the most visible symbol of the decades-long Cold War–was finally destroyed, just over two years after Reagan had challenged the Soviet premier in a speech at Brandenburg Gate in Berlin: “Mr. Gorbachev, tear down this wall.” By 1991, the Soviet Union itself had fallen apart. The Cold War was over.