I was half drawn into this. But the Moussaoui trial makes me feel confident it was al Qaeda, and not the U.S. government sabotaging its own people:
"Moussaoui, 37, a French national of Moroccan descent, admitted last year that he conspired with al Qaeda, the terrorist group responsible for September 11, to hijack and crash planes into prominent U.S. buildings.
Until he testified at his trial, Moussaoui insisted he had no role in the plot or advance knowledge of specific plot details.
But on the witness stand, Moussaoui said he knew in advance of the plan to crash planes into the World Trade Center and was to pilot a fifth plane into the White House on September 11.
Moussaoui's self-incriminating testimony severely damaged the defense case. His attorneys suggest that Moussaoui hopes to become an al Qaeda martyr."
http://www.cnn.com/2006/LAW/04/06/moussaoui/index.html
Obviously he wouldn't admit to all of this if al Qaeda hadn't even been involved--just the opposite.