Would not surprise me at all if there is a huge nest of would-be terrorists in the heartland of the US. The attacks on NYC and DC might be a ruse to keep focus on big cities, when in fact, more damage could be done 'out in the middle of nowhere' where movement can go almost unnoticed.
Actually it's easier to hide in the urban areas, everyone seems to know each others business in the rural areas, and they (rural) notice more minute changes....