The US was sleeping on watch. Pearl shouldn't have happened. We had told Imperial Japan to get out of China, armed the Chinese in their war with the Japs, and embargoed Japanese oil which put them in a position of accepting defeat without a fight and likely colonization or going to war with the US.
They sure didn't tell me this stuff in school. The story I got was that everything was fine and then one day those sneaky Japs attacked us completely out of the blue. Yes, they were ungentlemanly and attacked prior to formally declaring war but a retarded child could have foreseen the attack.
It was their error and our good luck that they didn't mount an invasion of the islands.