The first seeds of the Cold War between the Soviet Union and its socialist states and the Western democracies were actually planted before the end of the Second World War.
The three largest and most powerful nations opposing Nazi Germany were the United States, Great Britain and the Soviet Union. This grand alliance was wrought with suspicion on both sides. The Soviet Union's Premier, Joseph Stalin, believed the Western Allies were allowing his nation to bear the brunt of the German onslaught. He feared they held a secret goal of sweeping across Europe late in the war and installing their own governments once Germany was defeated, with his Red Army too depleted to resist.
The debating and mistrust continued at the February 1945 meeting of the "Big Three" Allies in Yalta. By this time, it was apparent that the war in Europe was to be over soon. What was not clear was how the peace would be handled. U.S. President Franklin Roosevelt and British Prime Minister Winston Churchill wanted assurances that the Soviet Union would hold free elections in the Eastern European states the Red Army had liberated through their drive west to Berlin. Stalin wanted assurances that he could keep his military stationed in countries like Poland and the Ukraine as a buffer against further aggression. The three also debated on how to divide the defeated Germany, and in particular, its capital city.
Berlin became a microcosm for the postwar situation in Europe and eventually the Cold War itself. In the summer of 1945 the Third Reich was defeated and the Allies divided Germany into four sectors (one each for the British, French, Americans and Soviets). In the first few years of occupation it was unclear which direction the country was headed. As the rubble was cleared out, the Nazi military machine dismantled, and the displaced peoples of all sides relocated, Germany seemed an untouched piece of clay ready to be molded. Parties on both sides had their designs for an urban utopia in cities like Berlin and Munich, and a simple, agricultural system in the countryside. Each side hoped their new system of nation-building would spread throughout a shattered Europe and replace some of the Old World establishments.
The capital of Germany remained Berlin. This resulted in a delicate and volatile arrangement as the city was also divided between the same four nations, yet it was located in the heart of the Soviet sector. In other words, the American, British, and French sectors in the western part of Berlin were to become an island of democracy surrounded by a region that was shifting toward socialism and communism. As the dust settled and the actual rebuilding began, distrust between the camps caused leaders in post-war Germany to polarize themselves and their efforts. Intelligence services that once cooperated against a common enemy were now spying on each other and stealing information. In the Soviet sector of Germany and throughout Eastern Europe communist governments were elected, although many doubt the fairness of some of these elections. The Western Democracies feared the impoverished German populace would turn to a communist government rather than starve under their strict sanctions. They shifted their policy toward one of rebuilding West Germany's economic infrastructure and using it as their own buffer against communism's spread through Europe. They intended it to be a shining example of the vast resources of democracy in the face of their newly forming rival. East Berliners began fleeing to the west of the city in droves, and early versions of the Berlin Wall dividing the city were constructed. In 1948 the Soviets prevented food and supplies from reaching the citizens of West Berlin as the entire city was surrounded by their military. The United States took a chance and made a massive supply drop from cargo planes in an event known as the "Berlin Air Lift." This further polarized the two competing superpowers.
In 1949 the nations of East Germany and West Germany were formally created. In this same year the Soviets became the second nation to detonate an atomic bomb and the "Red Scare" spread throughout the Western World. An Iron Curtain had descended along the very center of Europe.