some things to think about from a neutral outsider.
It is oft times easy to forget that the attack on Pearl Harbor was not exactly unprovoked. it was, as you were a "preemptive strike", as you will understand when you read about the dynamic in relationships between the Empire and the US prior to US involvement in WWII.
now, the US knew it was forcing Japan's hand, but it also had interests in, I believe, Manila ( or some other place, something about rubber production) and when it saw Japanese expansionism as a threat to it's interests it tried to choke the Empire, in effect setting in motion the events that would lead to US involvement in the conflict.
that being said, the Japanese were INSANE during the war because they had religious fervor about it, you have to remember that the History of Shinto Buddhism in Japan was strong and everyone that was in some way better or bigger or awe inspiring in anyway was "divine" in other words, they fought for their emperor who they believed was a sort of deity.
"kamikaze" means "divine wind" not "death wind" or "death from above wind" why do you think that is?
so, while it doesn't justify them, it does explain their viciousness when pursuing the expansion of the empire, ironically enough adapted from a faith that was based on the search of compassion and wisdom (sound familiar?) so they committed horrible atrocities, but, sadly, so did everyone in WWII.
everyone.
in Japan's defense though, and like The Lizard Mentioned, Pearl Harbor was a Military target and when the bomb sites for the two A-bombs were selected, military targets were also offered, but the US command deemed that civilian targets would have a greater "psychological impact" (again, that sounds familiar) and thus chose them.
and while Pearl Harbor was hideous, soldiers know war.
I've seen photos of Children charred and half-dead women, with their flesh almost falling away from their side.
It just seems like....I don't know.
I really don't.