If war broke out tomorrow....

[alien space marine]

You cannot forget that Japanese military philosophy at the time conciderd surrender or peace as a sign of cowardice and dishonnor infact soldiers were orderd to commit suicide rather then be captured,Japan had been militaristic for centuries and their own pride and arogance prevented them from seeing reason.While there was definently some who wanted to end the war the ones in charge wouldnt untill they got their asses burned too the ground.

I think the Nuking regretably was inevitable,It was to show that those Japanese zealots had zero chance of winning and if they didnt call it quits they would be wiped out off the face of the earth one by one and be remeberd as idiots and fools for not surrendering.