That it could happen here is a given, even more so today, than a few years ago at ISIL's peak.
If you haven't read "Day of Wrath", get it & read it
It will change your perspective about a serious attack here.
Obviously, it is fiction, but the possibilities presented are beyond possible, at this point, & have become much more likely to occur.
It's a scary scenario to anyone with even 2 brain cells to rub together.
MM