I don't know the exact involvement of al-Qaeda or Hussein. But there was definite Iraqi involvement. Nichols or McVeigh could not have built that bomb without technical help.
VEry plausible they got the technical help (and money?) from al-Qaeda through the Filipino connection.
And then there are the "cutter charges" placed on the support columns some of which did not trigger, hence the call that there are "still devices in the building" during rescue ops. And who went in to disarm and retrive those??? Nice cover up on their part.
Also just how did the "truck bomb" take out the bulk of the fedscum building but not do near as much damage on the other side of the street? Oh yeah and the crater under the truck was minuscule compared to the building damage. So are we supposed to believe that Mc Veigh made a shaped charge out of the truck?