Now, the issue is:
(A) honoring our word to the Kurds, et al, who trusted us, (if for no other reason, so that other will trust us in the future);
(B) not allowing Iraq to become a chaos s-hole like Somalia and/or Afganistan, which breeds jihadis; and
(C) not allowing Iran to take over Iraq, which it would do if we let things run the course.
Complex? Certainly.
But Ron Paul's and Jack Murtha's cut-n-run approach is not the answer.
Then we shouldn't be so foolish to give our word to people who wouldn't do the same for us. In any event the Kurds can take care of themselves. And I actually agree to an extent. We can wait out the Sunni-Shia civil war in Kurdistan as well as Kuwait and Qatar.
Iraq is already a training ground for jihadists, and continued occupation won't change that. By the way, the outcome of imperial wars is for some of the natives to repatriate to the mother country. The same thing is going to happen here, and the odds are near certain we will import a terrorist cell.
Iran already operates with a relative free hand in southern Iraq. Again, an additional 20,000 troops in the Sunni region won't change that. (We don't dare step heavily in the areas controlled by Shi'ite militias, as they enjoy broad popular support.)
No good solutions at this point, frankly, which is what some of us were saying from the start.