I'm not sure how you could call The Iraq war "a complete and utter success" as 58539672 has. Murdering 141,802 people cannot be called a success. But it can be called unjust, contrary to what Jonnykelly said. It can especially be called when the war was illegal according to a U.N. charter. How dare you say "we defeated and conquered the strongest middle eastern nation"! Is that what mattes to you, conquering and murdering hundreds of thousands of innocent people! Is that what it means for you to be an American?
The United States declaring war on Iraq after 9/11 was wrong on many levels; it was done for the wrong reason, the ulterior motive was insensible and there was no clear exit strategy. Bush Sr. Made the right choice when he decided not to overthrow Saddam Hussein, because if he had, it would have destabilized the country and forced us to occupy, and in turn rule Iraq.
If your talking about our motives for invading, then their are valid arguments for both ends. If your talking about the invasion itself, then it was a complete and utter success. We defeated and conquered what many considered the strongest middle eastern nation in 21 days with minimum casualties. If your talking about the occupation (and yes, that is different than the invasion) then we had very few problems until we started handing over authority to the new government. Our allies simply weren't ready to do the job properly.
I acknowledge that in the long run, the invasion turned out badly. But if you look from the president's point of view, it's a little more understandable. 3000 Americans were killed brutally. The public is demanding that someone pay. Saddam Hussein is a corrupt leader, and he is known to be housing terrorists. While it's not a great reason for invasion, it isn't totally unjust either.