Oil played a big part in the military and simply economic plans of each country. Japan entered through that specifically but also Japan for some time felt as though they were treated as a “little country” they wanted to be a world power so the best way to get to that is a booming economy and bolstered military. At that time the U.S. supplied Japan with a majority of it’s fuel. As did the U.S. to Germany but when the U.S. entered the war it was very much a moral cause but at the same time it was over resources. Germany, Japan, and the U.S. shortly before the war had a time of great economic gains.