When people want evidence of government foreknowledge (at the least, letting it happen) on 9/11, they really need look no further than the concerted inaction of the men at the top of the U.S. defense command, meaning Bush, Rumsfeld (along with his deputy Wolfowitz and the officer in charge at the Pentagon’s National Military Command Center), and the Acting Chairman of the Joint Chiefs. The VP was the only one who actually did something during the attacks, and what he was doing was virtually participating in the attacks (tracking Flight 77 on its way to the Pentagon) according to the eyewitness account of the Secretary of Transportation, whose testimony the 9/11 Commission had no choice but to ignore.
I actually give Bush the benefit of the doubt, because I don't think that conspirators would let a person that stupid in on the plot. Bush was a puppet and a useful idiot in the cover-up, dragging his feet on appointing a commission for as long as he could, and then (no one could make this up) trying to appoint Henry Kissinger to head it. I’m sure it was also not Bush’s decision to sit around the Sarasota schoolhouse for half an hour after it was known that America was under attack and his whereabouts as a potential prime target were known. That’s on the Secret Service, presumably under orders from someone who somehow knew that Bush and the school kids and teachers were not in the slightest bit of danger. Just keep Bush there doing nothing for as long as you can.
But what about our other defense “leaders”? There’s the rub. The Secretary of Defense, the Acting Chairman of the Joint Chiefs, and the chief operating officer at the NMCC in the Pentagon all went into hiding during the attacks. Rumsfeld holed up in his office listening to his daily CIA briefing like nothing was happening while his subordinates tried to get a handle on things, then he went outside the building after the Pentagon itself was hit so that he couldn’t be found by those same subordinates. (Those concerned subordinates didn't include Rumsfeld deputy Wolfowitz, who continued with a routine Pentagon meeting after both towers were hit because he didn't think there was anything to be done at the moment.) The Acting Chairman General Myers holed up with Senator Max Cleland on Capitol Hill to chat about his confirmation, not to be disturbed by anything as distracting as an attack on America. The NMCC chief operating officer just happened to have that morning off, leaving the NMCC in the hands of a greenhorn, then showed up to "take charge" when the attacks were over. In sum, when the attacks were all over, the leaders of the U.S. defense command came out of their holes to suddenly assume their duties.
It is telling that the 9/11 Commission didn't have the guts to ask Rumsfeld or General Myers to explain their behavior, even though the Family Steering Committee specifically requested that the commission ask Rumsfeld to explain himself. Myers openly committed perjury right in the middle of his confirmation hearing testimony a few days after the attacks, and was rewarded for his lying with unanimous confirmation. It is also worth noting that his fellow military brass told so many lies during the 9/11 hearings that the commission considered having them indicted for perjury. But of course the commission didn't have the guts to do that either.