Pearl Harbor was not an accident, a mere failure of American intelligence, or a brilliant Japanese military coup.
It was the result of a carefully orchestrated design, originated in the Office of Naval Intelligence. According to a key memorandum, eight actions were taken to make sure America would enter the war by this means. Pearl Harbor was the only way, leading officials felt, to galvanize the reluctant American public into action.
This great question of Pearl Harbor--what did we know and when did we know it?--has been argued for years.