Adastral,
Your point about America's involvment in WWII prior to Pearl Harbor is flawwed. You are looking at it through the jaundiced eyes of time. Prior to 1941 America did not wish to be a world power (militarily) we were quite content to see after ourselves. Our nation is huge, vast, and can supply much if not all of what we needed. On the other hand may European nations had to trade, interact etc. for survival. We did get involved belatedly in WWI, however, as sonn as it ended, America quickly returned to its isolationist ways. It took a direct attack on Pearl harbor to force us to enter the war. Now many in the world expect, or feel it is America's duty to rush to the aid of any nation that needs it, but there was a time when the world looked elsewhere.