Why not? The war part of the mission in Iraq was accomplished in short order. The peacekeeping crap was botched. We shouldn’t be in that business anyway. We should break things where they need to be broken and leave.
That’s exactly the point - there was still a ton of work to be done. And at the severe risk of getting off topic, we effectively signed up for that job when engaging in Iraq in the first place. Large military missions have never been about “get in and get out”... we rebuilt Europe; we rehabbed Japan. Those things are necessary to avoid...well, exactly what has happened in Iraq.