There is a ton of documentary evidence for the change, in the form of statements and publications of those in and around the Bush Administration advocating the policy and noting the opportunity for it provided by 9-11. You don't need Chomsky, if that's whom you're referring to, to show this. Of course, appreciating Chomsky helps you appreciate evidence when it turns up.
As for the success of the Allies in Afghanistan (which I, like many others, underestimated), that story has many chapters yet to unfold.
mbs
----- This maybe true, but I doubt it. If it is it would be thanks to Osama. People seem to forget that Bush repeatedly said he was against nation-building during the 2000 campaign and Rumsfeld echoed this up until September 2001. Also, I'm skeptical of those who once predicted either that Bush was going to starve Afghanistan into submission or that the heroic Afghan fighters would do unto the Allies what they did to the Soviets.
Speaking of the Soviets, since the Cold War is over maybe the hyperpower can risk a little overreach.
Peter