Even before I gave up TV, the common refrain from those in and around government (granted, quite a large and revolving motley crew) through the mainstream media (another motley crew) were regularly being quoted to the effect of "it's a given that there will be another future terrorist strike within continental united states. it's only a matter of time, when and how"
If one has the perspective that those in and around government are the true terrorists, it makes perfect sense that they and their crystal ball are in a better position than anyone else to be so confident in declaring there will be a future "terrorist" event. Oriented as such, even the detective team of Barney Fife and double-not spy Jethro Bodean could sniff out this one.