The end of World War II did not produce an enduring peace, but rather a new and continuing conflict between the former Allies. Soviet expansion in Eastern Europe was countered by a policy of containment, a policy that allowed the Soviets a free hand in the East, but firmly opposed expansion toward the West. In support of its western allies, the United States provided military and financial assistance under the terms of the Truman Doctrine and the Marshall Plan.
The tension between the Soviets and the West tended to focus on the status of Germany and particularly that of Berlin. The restoration of civilian government in Western Germany and its eventual admission into NATO led the Soviets to establish East Germany, create the Warsaw Pact and the formal division of Europe. Berlin, lying deep in East Germany, was particularly vulnerable to changing political tension between the superpowers. The divided city was truly the symbol of the division of Germany and of Europe.
The Cold War policy of containment was based on the belief that, should the West be politically firm and economically prosperous, it could outlast and overcome the aggressive tendencies in the Soviet system. In the end, the "cost" of waging the Cold War was more than the Eastern economies could bear.