I really struggle to believe that any major power could plan and execute a conspiracy like this - for no other reason than that they would rely on too many ordinary citizens to execute the plan and one of them would be sure to talk.
However, I was always a bit perplexed by the lack of aircraft debris at the Pentagon, which kind of lent some credibility to the idea that it was a rocket attack, but this video on YouTube explains why nothing was found pretty well. And it's narrated by Carol Vorderman, so it must be true.
http://www.youtube.com/watch?v=dWpRG...elated&search=