It's pretty funny how ridiculous some of the posts are in this thread. As far as invasions go, whether you are for them or against them, they don't get any better than the invasion of Iraq. It was quick and the number of American casualties were minimal.
Our military definitively proved that a small, well trained and maneuverable force is highly effective in an invasion. Once the enemy forces have been neutralized, you move into a different phase. You are no longer an invasion force, you are an occupation force. An occupation needs way more people than an invasion force, because they are a peace keeping force. They have to guard and secure facilities.
We got an A+ on our invasion and a D- on the occupation. Security forces weren't moved in quick enough and with enough numbers to secure weapons stores and other facilities. We paid dearly for that mistake, because all those weapons were converted into IEDs and used on our troops.
The blame for that falls completely on the shoulders of Rumsfeld for continuing to insist on keeping the occupation force small, despite what all the ranking officers were saying; and on George Bush for going along with Rumsfeld. If the transition from invasion force to occupation force had gone smoother and the occupation force had been significant enough, we would not be discussing this now.
As to topic, whether you agree that the U.S. should have invaded Iraq or not, allowing what is happening to continue is like pissing on the graves of all the soldiers who died there.
I hate Monday morning quarterbacks, but the thing I hate worse is when leaders are in denial about a crisis and are incapable of seeing an obvious way out. This has happened under the past 2 administrations.