I don't believe in most of the conspiracy theories but I do think that the Intelligence agencies must of knew about the planned attack on the towers but allowed the attack to happen so it would give them the green lights to and invade Afghanistan and then Iraq which IMO was criminal (especially the invasion of Iraq).
Thats my thinking
.However to actual accuse them of knowing about the attack on twin towers and allowing it to go ahead is quite frankly ludicrous,im aware our security services peddle in a grubby underhanded trade,but no way i can accept that theory.
scot