I've done business in Japan for over 15 years. One thing that really sets the nation off is a threat to their islands. They are nearly 100% dependent upon outside resources. Threaten it and you have threatened the people. The one true natural resource they have is their people and their culture. This is defended overtly and subtly. It is hard for a round eye to ever break that "code".
So you can see that cutting off their oil and coal, as we threatened, was cause for war.