Al-Quaeda was part of a network of Wahabist terror organisations; wahabism is chiefly sustained and funded by the Saudi establishment, and Al Quaeda had its financial base there. Most of the perpetrators of 9/11 were Saudi, and two of these had strong contact with Saudi intelligence. There are circumstantial pointers too, such as the head of Saudi intelligence being summarily dismissed days before the attacks, having served in post since 1979.