The fact is, no WMD were found in Iraq. The intel was wrong, and probably intentionaly manipulated by Bush and his team to get the data they wanted, which was then used to scare everyone into thinking he had them.
Manipulation was not needed.
Post Gulf War I, Saddam went total passive-aggressive against the West. He refused to play nice in any respect He couldn't just build country with a normal civilian economy and normal internal policies, he had to tweak the West's nose at every opportunity, playing the spoiled baby acting out because it didn't get its way. We had to put up no-fly zones, protect his neighbors, stop his smuggling, and deal with him playing "you can't catch me" with weapons inspectors. When someone is playing "you can't catch me" and you know he started out with some, during the game you've caught him several times with some and caught him smuggling in all sorts of prohibited components and caught him at attempts to make more, and then the game continues and you go through a short stretch where, no, you haven't found any fully finalized and functional WMD's, do you wrap up and go home on the assumption that you got them and that everything is in order and will be hunky-dory until the end of time, or do you take the safe route and keep looking under the real possibility that maybe he just got better at hiding these things? The inspectors did NOT have free reign to go wherever they wanted in Iraq at whatever time, and weapons ARE portable.
Saddam played these games down to a very short fuse, then 9/11 happened and the concept of the threat posed by WMD's out in the world suddenly came crashing home. What if someone set off a chemical weapon bomb in the Manhattan subways? What if a dirty bomb was set off on the streets above, contaminating everything for hundreds of years?
This isn't some distant concept of science fiction.
Saddam thought he could play his games in safety. He thought we were soft -- that as long as he didn't do anything directly against us that we wouldn't have the balls to step up against him. He was wrong. 9/11 pissed us off in general and we took it out on that fucker. No cutsie -- he repeatedly violated several U.N. resolutions and so made it clear that the only way to get him to ever be in compliance was to invade, and the civilized nations of the world were with us in that. WMD's or not did not matter at that point; his system alone posed a threat -- that of the endless babysitting of an unruly child -- so his system had to be removed. The weight of his history and his continued actions did strongly support the notion that there still were WMD's in Iraq so why wouldn't that belong in the pile against him? There was
certainly nothing to say, "Holy shit, Iraq has been scrubbed clean! We looked in his mouth to see if Saddam brushed, and he did! What a good boy!" His mouth was clamped shut, he was dragging his heels -- it looked like he was hiding something so we went with, "He's hiding something," on that front. If he had been completely transparent on that front it still would not have excused everything else, so the invasion was still completely justified.