''If the US was involved, or let’s just say that Al Qaeda didn’t act alone, how come no terrorist talked about it?''

 I don't think anyone would believe any terrorist that said anything about America being involved. Also IF the US was invovled it would make them and Al Qaeda partners of sorts and there would obviousley have been and agreement that no one would say anything about American involvement.

 But as I said that's a pretty big 'if'. It's quite unbelievable really.