Q: Would it have happened if we had had 25,000 troops still on the ground?
Petraeus: No one knows whether forces there would have given us an influence. That’s the question for the ages. They were out of combat, out of the cities and out of the advising.
So you have to ask what the mission would have been. And again, without knowing what mission Prime Minister Maliki would have allowed them to do, it’s hard to say how much influence they might have achieved, again noting that there was a quite a robust security assistance force and that did not seem to translate.
http://www.pbs.org/wgbh/pages/frontl...nt-a-surprise/