There is only one politically serious explanation...

page type::article thing type::quote

Quote
There is only one politically serious explanation of this now-indisputable fact: powerful forces within the US military/intelligence complex wanted a terrorist incident on US soil in order to create the needed shift in public opinion required to embark on a long-planned campaign of military intervention in Central Asia and the Middle East. Whether or not they knew the scale of the impending attacks and what the precise targets would be, they acted in such a way as to block the arrest of known terrorist operatives and allow them to carry out their plot.

Origin
This has been attributed to Lt. Col. Anthony Shaffer, but it appears to originate with an article on the World Socialist Web Site.

Attribution History

 * 2005-08-19 9/11 commission told of Atta cover-up: source of quote
 * 2005-08-19 Never Forget: correctly attributes it to WSWS
 * 2005-10-02 Maybe they'll start listening now ...: a commenter attributes it to a source no longer available
 * 2006-09-14 Treason Inc.: Bush Junta Complicity in 9/11: implies via formatting that Shaffer said it
 * 2007-10-13 All the "Conspiracy Theories" About George W. Bush have come true: attributes it to Shaffer
 * 2007-10-15 repaste of the Existentialist Cowboy post: same misattribution, but links to a source no longer available