In your scenario, America would have had to maintain an enormous force for an insane amount of time, perhaps decades. I don’t think that is a good solution to the current problem.
Do you think we should have maintained an enormous presence there or do you have an alternative solution?
And what would you call our presence in Europe, Japan, and Korea? After any significant conflict, we have had to maintain a credible military presence to keep that part of the world stable and on an acceptable path.
We are the main presence on the planet for a number of reasons and one of those reasons has been keeping former enemies honest.
We should have maintained a large, well-trained and credible force in Iraq. I won't argue that GW Bush was right to go in - but once in, we had to finish the fight and keep Iraq and its neighbors stable.
The other choice is to renounce our place in the world, let others like China, Russia, Iran, and so on take the lead and get ready for what happens next.
Don't like having to maintain a preeminent military force? New Zealand beckons.