I've been reading Dower's"Embracing Defeat: Japan in the Wake of World War II" and I think embarrassment is a significant factor, though this is not exclusive w

I've been reading Dower's"Embracing Defeat: Japan in the Wake of World War II" and I think embarrassment is a significant factor, though this is not exclusive with your explanations. While the nation as a whole may not exhibit signs of shame, the Japanese culture at the time seemed to encourage the direction of moral responsibility upwards. So while (particularly) the need for oil can't be overstated in this case, I think that there was a degree of self-consciousness that DID characterize the actions of the upper military acting on pressure from those "beneath" them. I don't think the pressure was directly to attack, but there was enough power concentrated in the hands of the few that their decisions were allowed to be implemented rapidly and without much resistance.