Ice, Ice, Baby! The Coldness of the Cold War

Reasons contributing to the Cold War: the US' paranoia over communism, general distrust for Stalin in America and Truman in the USSR, and need for the economies of both the US and USSR to set up identical systems in other countries after the end of WWII. All of these reasons created high tension between the US and the USSR. However, I feel as though there was one MAIN cause that caused the Cold War, and that was the atomic bomb.
The bomb was not needed to end the war in the Pacific, so the reason that the US even dropped the bombs on Japan was to end the war before the Soviet Union could join in and get a say in the fate of post-war Asia. This signaled to the Soviet Union that there was a definite aire of hostility between the two countries, and they could sense it. Neither country had completely trusted the other, but now it was more "out in the open". High-stakes competition erupted, and thus began the Cold War. I am not saying that it was completely the fault of the US, however. During the post-WWII agreements between the Allies the Soviet Union had been demonstrating a desire for power, and to gain the upper hand over the US. The US realized this, and took the more decisive step in acting on it by dropping the bomb. After the USSR saw throught the whole "saving lives" smoke screen, it became apparant to people in government, Stalin in particular, that they needed to act against the US, but indirectly. This was to happen by attempting to spread Communism, and develop military advantages. They began work on their own nuclear weapons, which let to very close calls later on. This was particularly evident during the Cuban Missile Crisis, which was the closest the world had ever come to nuclear war.
So no, fingers should not be pointed at any one country, or event, for solely causing the Cold War. But the dropping of the atomic bombs on Japan was definitely a major turning point in world history.

The Potsdam Conference

Okay, so for my topic I chose the Potsdam Conference. The conference took place in Potsdam, Germany, near Berlin. The "Big Three" leaders (Truman, Stalin, Churchill, and Attlee after Britain's election) met there to discuss and come to agreements about how to deal with post-war arrangements in Europe. The meeting, which ran from 16 July 1945 to 2 August 1945, was recorded in history as the last true conference of World War II. The leaders had trouble agreeing on most of the topics (reparations, the Oder/Neisse Line, how to deal with Japan, Russia joining the war in the Far East, and Allied control of defeated Germany), but did come to a concise decision when it came to Japan. During the conference, the leaders released the Potsdam Declaration, which demanded the Japan agree to their terms of an unconditional surrender, or face "prompt and utter destruction". Truman had told those at the meeting that the United States had created a weapon of awesome power, but that seemed an insignificant detail to leaders with millions of troops stationed in Eastern Europe. The Potsdam Declaration contained no direct reference to the atomic bombs, only that doom awaited Japan if she did not surrender. The warning went unheeded, and the atomic bombs were dropped on Japan about one week later.