Commonly held general causes for WWII are the rise of nationalism, the rise of militarism, and the presence of unresolved territorial issues. In Germany, resentment of the harsh Treaty of Versailles, specifically article 231 the "Guilt Clause", the belief in the Dolchstosslegende, combined with the onset of the Great Depression fueled the rise to power of Adolf Hitler's militarist National Socialist German Workers Party (the Nazi Party); meanwhile the treaty's provisions were laxly enforced, due to the fear of another war. The League of Nations also failed in its mission of preventing war, for similar reasons. Closely related is the failure of the British and French policy of appeasement, which also through fear of war, gave Hitler time to re-arm.\n\nJapan in the 1930s was ruled by a militarist clique devoted to Japan's becoming a world power. Japan invaded China to secure additional natural resources to compensate for Japan's lack of natural resources. This angered the United States, which reacted by making loans to China, giving China covert military assistance (see Flying Tigers), and instituting progressively more inclusive embargoes of raw materials against Japan. The embargo of oil and other raw materials by the U.S. would have eventually wrecked Japan's economy; Japan was faced with the choice of withdrawing from China or going to war in order to conquer the oil resources of the Dutch East Indies. It chose to go ahead with plans for the Greater East Asia War in the Pacific\n\nAs far as the US joining, we Pearl Harbor pushed us into joining, but we were supporting the allies via trade for much of the war anyway, and many people were pushing us to join. We hesitiated because for many people it seemed like a War that had nothing to do with us, we really weren't protected ourselves, just coming to the allies aid. Remember, we weren't superpowers until after WWII.