Herewith my annual plea that Roberta Wohlstetter's 1962 classic study, Pearl Harbor, be read by anyone interested in strategy, intelligence, and the post-9/11 world. (Here's a link to the googlebooks version.) As in 9/11, as Wohlstetter shows, U.S. leaders and military knew something was up, but the different "signals" were misinterpreted or not shared with other parts of the government. And unanticipated Japanese technological progress (combined with boldness) made possible a stunning attack. Try to track down her study of the Cuban missile crisis as well.
As I write this, I recall that the book was first called to my attention by the late Claremont professor Bill Rood. It would be fitting if this and Roberta Wohlstetter's other work were recalled at the 2012 APSA at the Claremont Institute panels.