when did the cold war start

The Cold War started after the surrender of Nazi Germany in 1945, when the uneasy alliance between the United States, Great Britain, and the Soviet Union began to unravel. The tensions stemmed from disagreements about the postwar world, especially regarding the control and political future of Eastern Europe. Key moments leading to the Cold War include the Potsdam Conference in July 1945 and the subsequent division of Germany and Europe into Western and Soviet-influenced zones. The Cold War was solidified by 1947-48 when the United States implemented the Marshall Plan to aid Western Europe, while the Soviet Union established communist regimes in Eastern Europe. The Truman Doctrine of 1947 marked the U.S. policy of containment against Soviet communism, officially setting the stage for the Cold War. Thus, the Cold War is generally considered to have started in the immediate aftermath of World War II, around 1945, becoming more defined politically and ideologically by 1947-48.