This is fundamental:
In a post
at Booman Tribune that examines Bush's various failures, author Steven D writes: (emp add)
National Security Failures
Under his watch, the 9/11 attacks occurred despite the insistent and constant warnings he was given by the principal intelligence and counter-terrorist analysts in the government that terrorist strikes against the United States were likely to occur during the summer of 2001. Then he tried and failed to cover up his own administration's malfeasance. He failed to eradicate Al Qaida as a force in the winter of 2001-2002, opting instead to divert resources to an invasion of Iraq, thus allowing Al Qaida and its Taliban allies to reconstitute themselves in Western Pakistan and Eastern Afghanistan. He did nothing to reign in support for radical Sunni based terrorists affiliated or aligned with Al Qaida by Saudi Arabia and Pakistan, despite proclaiming them as our essential allies in the War on Terror.
Bush benefited politically from the attack, dispite the fact that he was dismissive of the threat. It gave him the political edge that enabled him to invade Iraq and authorize unconstitutional acts like spying and torture.
It's a remarkable instance of someone being rewarded for failure.
Bush gets criticized for the Iraq War, Katrina, poor economic stewardship, obstruction on environmental issues, and so on. But rarely does he get blamed for 9/11. Why?
It's the big lie. It's such a massive violation of the public trust, that no-one can think about it for too long without being overcome with such rage that they want to beat the shit out of Bush, and since they can't do that, they repress it. He was then able to judo flip that unhealed wound in the American Psyche into support for the Iraq War. We'll see the aftershocks of this for the rest of our lives.
Because a lot of people can't draw a line between "Bush benefited from the attacks" and "Bush executed/directly caused the attacks."
The first is clearly true, the second may or may not be true, but makes you look and sound like a tin foil hat conspiracy lunatic by even being associated with it.
Bush II could not have formulated the 9/11 plan, he's just not that inventive. However, the same thing can not be said about Cheney, Rumsfeld, Bush I, and Kissinger.