Evidence of foreign intelligence backing for the 9/11 hijackers?

http://www.guardian.co.uk/print/0,3858,4976002-103677,00.html

:eek: Uh, what the hell? This is the first time I’ve ever heard of this - is there any truth to it?

Maybe this has no factual answer and should go in Great Debates? I was hoping someone would be able to give me a link to supporting facts outside of the opinion piece I link to, but if not…