Besides, the americans had already used biological agents against their own people. So attacking them was clearly justified, even if the Japanese were not able to defeat the FDR Dead Enders who had imposed all of the dark evils of their tyrannical regime upon the peace loving people of america who would have greeted the japanese with flowers as liberators were it not for the FDR Dead Enders and their completely failed fiscal policy.
Ok, yes, many would argue that the Japanese Pre-emptive strike was misplaced. But hey, it would have been a hardship for the japanese to have attacked the Islamic Extremists in Iran. So why not attack the FDR Dead Enders?
Ah yes.... and to think, prior to 9/11, americans once thought it was impolite to attack a nation without a declaration of war. Thank GOD that the day that changed everything has corrected those defects in the failed liberal ideology.