To what extent was the USA responsible for the outbreak of the Cold War?
I believe the US shares some responsibility for the outbreak of the Cold War with the Soviet Union, but to a lesser degree. By 1943, the alliance between the two countries fighting Germany was already strained. As soon as the war ended, the Cold War was inevitable.
Think of it, the US and the Soviets were really the only two empires surviving the war. France had been occupied, Britain was broke, and Germany and Japan devastated and defeated. The remaining two empires had completely opposite forms of government with different goals for foreign policy. The US could have simply not reacted to Soviet communist expansion and the Cold War would not have happened, but that was pretty much impossible in the environment of the times.
To answer this question, first, one needs to look at at least 4 historical documents: Atlantic Charter ('41), Teheran Conference ('43), Yalta Conference (Feb '45) and Potsdam Conference (Jul '45). Second, reading (best) biographies of, or reading about Roosevelt, Truman, Kennan, Marshall, to get a flavor of the US position and doing the same for Stalin to get a sense of the Soviet position, would give you some perspective of the "playing field." (Adding Churchill, de Gaulle and Adenauer would be best.) Third, develop a solid understanding of the geo/political importance of Germany to both the West and the East post- War II. Fourth, remember that rarely is one country "responsible" for historic events.
This doesn't specifically answer your question, except to point out that many factors affected development of the Cold War, and through your own "discovery learning," you will develop a better appreciation for these factors and for the historical period.