Please. You're smarter than this.
Most of the terrorists were selected with Saudi backgrounds because the visa requirements for that country were so loose.
There are enough real idiots around. Don't work at it to pretend to be one.
The terrorists were al Qaeda, based in Afghanistan, with the support of the government of Afghanistan at that time. This was easy to find out.
Nobody in Afghanistan said "are we really going to blow up a part of two cities in a country up to its ass in nuclear missiles?" Deterrence is for sane people, who are not "brain dead."
Which, of course, is the point you evaded.