First off, during the New Deal era, America focused on isolationism, and tried to keep to herself. The republican party, whose stance at the time was "America first" eventually realized that were Britain to fall, the nazis would be headed for us next. So, we discarded our neutrality stance in favor of helping britain defeat the nazis, so we could protect ourselves. This is relevant to the question for 2 reasons. 1, we needed to keep a tight grip on Germany so that Britain could rebuild before Germany so as to prevent a fourth reich (the German people were still very passionate about imperialism) and 2, we just wanted to show the communists that we had a big dick (just lile vietnam) in that, we could conquer a foreign power just as easily as they could, and the intention was to show Russia we were a force to be reckoned with. "Speak softly, but carry a big stick" -Theodore Roosevelt