looking at it that way: 9/11 worked very very effectively as a sort of propaghanda supporting the idea of terrorism, which caused great fear across the world especially the US. fear can be used as a form of control. one way it is used is to conjur up plans for what the government refer to as extra security against the terrorists (remember, the terrorism thing has been milked by the government through the media in order to make it seem a bigger issue/threat than it is). in the nationwide fear, the public will agree to these new security efforts even if otherwise they would not have. "but it's protecting us from the terrorists...." one particular security tactic is the proposed use of id cards for everyone. i am not going to go into detail on the many cons to this, you can read them up online elsewhere if you want. anyway, this has been in the works for a long time. look up online and you will see why the government want the id cards and the lengths they're going to have them implemented.
so effectively, 9/11 = control, and has led way to the government attempting to manipulate the public
p.s. the government did not necesserily "cause" 9/11. i am not sure what to think in that respect. perhaps they "accidentally" made a "blunder" and did not prevent it from happening when they knew it was going to. maybe they did cause it.