Since the London bombings, there has been a palpable feeling in the air here in the U.S. that another terrorist attack is imminent. Maybe not as bad as 9/11, perhaps a train or subway bombing. Or maybe it will be something worse. There were fevered rumors circulating over the last few weeks about massive attacks on New York and Washington scheduled for Aug. 6 and 9, to mark the anniversaries of Hiroshima and Nagasaki. But now Aug. 6 and 9 have come and gone. More significantly, 47 months have come and gone since 9/11 without a major terrorist attack on...