Slightly off topic, but I guess WW2 was a series of separate conflicts that had been brewing / under way for a while but all got joined together due to the treaties that were in place, or shared political ambitions?
Japan had been conducting a war in China since 1936 ( I think) They needed raw materials to continue this war, all the raw materials they needed were there in South East Asia, with the colonial powers otherwise occupied in Europe they, concluded an alliance with Hitler, tried to knock the Yank navy out of the war at Pearl Harbor, invaded and plundered the spoils of the Philippines, Malaya, and Indonesia. The famous "Axis" did not operate as one, Germany needed to threaten the Allies with Japan and vice versa. Had they really operated as a strategic alliance, and had Japan advanced to India from Burma, whilst the Germans had advanced South from the Caucasus, and East from Africa, who knows what the outcome would have been. But both nations were military dictatorships and presumably organically incapable of trusting one another.