Listen to Pres Roosevelts speach to the nation on BigBadWulffs post above---I listen to it live that day. Lucky489 above said our country already knew it was comming--I had been hired to be one of the first to work at a newly planned air base a week before the attack. The planes at the air base near Pearl were moved close together weeks before so that they would be harder to sabotaged from the ground--and that made them easier to bomb.
I always remember the ending of the movie Tora-Tora when the Japananese comander said "Im afraid we have awoken a sleeping tiger"