Stinnett answers that and details the American plan to force Japan to make the first strike. I have never seen a better documented book! This is primary historical research at its best. When you are done with the book you will see the start of the Second World War in a different light. And, just to be sure, the book isn't necessarily anti-Roosevelt.
Perhaps the most interesting part for me was the review of American efforts to make sure the coming attack was kept secret. Also interesting was the fate of the army and navy commanders at Pearl who were kept out of the loop. I guess it was necessary to have a couple of fall guys.
Buy the book! Excellent! And, the proof! Wow!