Oh right, I forgot. You cannot possibly get into a building with public access that exists for the sole purpose of commerce without the central government acting behind the scenes.
http://www.cnn.com/2014/03/20/us/new-york-world-trade-center-intruder/
If a sixteen year old kid with an obvious lack of judgement can just walk around the WTC in the middle of the night after 911, the security before 911 must have been virtually nonexistent! It wouldn't have been difficult for a few people to plant explosive charges inside the towers in case the pilots failed. And again, if the government were behind this, they probably would've attacked less critical points in our nation that would still cause the desired public outrage. Points such as, for example, a nuclear power plant, the St. Louis Arch, or anywhere but the offices of everyone who would benefit from the ensuing war(for example, the President, the people working at the Pentagon, influential businessmen vying for access to oil against OPEC). And if the attack was launched by the govt. to instigate a war over resources, we would've made at least part of the Middle East into territories. Simple, really.
The US government being involved in the terrorist attacks on 911 is illogical. Every shred of evidence I have seen so far shows that there was undoubtably someone inside the WTC. I never suggested that I disagree with that point. HOWEVER it is highly unlikely that our own government was responsible for the attack. I don't say this out of trust for our government - I wouldn't put something like this past them - but out of a basic understanding of survival instinct. The targets were too vital for us to risk; if an attack were to go
too well, we've destroyed our own chain of command, economy, and military intelligence center. And a terrorist organization wouldn't need our asistance; bureacracy and sheer incompetence did the work for them.
To summarize, Al Qaeda had no need for the US government to be complicit in their plans, the security was already at a level far below what would be needed to prevent the attack, and the government, although it is concievable that they had a motive for such actions, the targets hit and the actions of the government following the attack don't fit the motive, or any motive.