We assert that the current, largely elected government of Iraq is, in fact, the legitimate authority in Iraq. If that is the case, then if they ask us to go, we must go. We must ask them to ask our troops to withdraw. We must then explain, humbly, that the wishes of a democratically elected government of a sovereign nation must be respected when it comes to their own territory.
Does the day we stop paying troops in Iraq, the defense contractors in Iraq, mean the end of the US commitment to Iraq? We must defend Iraq from any foreign army for a while, after all, we disbanded their military.
We must pay for training the Iraqis wish to receive, overseas, in both public administration and civil policing. We must pay for lots of stuff in Iraq that we have broken. Building new ministries, regional legislative, executive and judicial facilities, the foundation of any government, must be brought up to a certain standard, likely resulting in completely new construction in those locations.