In my opinion, I think the war with Japan was inevitable and, if not on Dec. 7th, 1941, then in a proximity not far from that date. You have to remember Japan's overall sentiment toward the United States at the time. Besides feeling as if the Washington Conference (of 1921/22 I think) was directed specifically toward them, by the U.S., in an effort to stem Japanese interests in the Pacific (I know, an oversimplified perspective), they also felt left out and betrayed after their WWI alliance with the U.S./Great Britain (i.e., Treaty of Versailles stuff). Add to that the oil and steel embargo, which the Japanese desperately needed at that time, being (after all) an island, they had really no choice but to time the Dec. 7th attack with their desire to capture the oil reserves of the Dutch East Indies. Don't forget, the Japanese people were in an increasingly impoverished state at the beginning of their expansionist efforts in 1935 China. This, they attributed to the betrayal by the U.S. for their efforts in WWI. The Washington Conference and the Oil/Scrap Metal embargo that followed raised Japanese anti-American sentiments to a feverish state.
Had all these factors come to a head earlier, or perhaps later, in history, then I think there might be some question as to the timing of a war with Japan, and if that war would have ever occurred. Why do you think Gen. Billy Mitchell and Admiral Richmond Kelly Turner were already predicting a war with Japan many years before 1941 in the first place? Because, under all the circumstances at that time, it was inevitable and, in the foreseeable future. Ahh, but we're just speculating right?
Anyway, a great book which spells it all out in great detail is, "The Eagle and the Rising Sun" by Alan Schom.
