If it walks like a duck, quacks like a duck (and tastes good to eat), its most probably a duck.. Irrespective of whether USA govt officially accuses it to be a duck or not..
So in other words, you have no evidence and you mean you're a conspiracy theorist too? Good to know. More and more bharatis coming out of the conspiracy theory closet. The fact alone that US has not officially accused Pakistan makes you a conspiracy theorist - look no further.
Why do you also believe the official 9/11 and 2008 Mumbai attack story, then? You do know that the same argument can be applied just as well to either of those.. being cherry pickers, are we?