If you let them build up without any restrictions, as AQ did under the Taliban and in Sudan, you end up with quantity and scale of attacks which border defense can't mitigate sufficiently.
I am off the impression that the quantity and scale of attacks which was seen in 9/11 is currently being restricted by a locked door in airplanes, and less passive passengers.
Terrorists have weapons other than planes, you know.
yeah,like Afghan soldiers are going to attack USA at its borders with tanks and fighter aircrafts... they did not give a f. about America until USA came to invade them.
Actually, rdl was referring to Bin Laden's folks who, as non-Afghans, were using the country for a base of operations early on to train.