I never liked the Powell doctrine (here is a piece by someone who has changed their views)--that one could only use force if one was willing to give the military whatever it needed to fight only those battles that have wide support and have easy goals to reach. That might be a slightly unfair characterization, but the idea was to have only Iraq 1991's and not Bosnia (Powell pushed against that rather successfully for some time).*
* To be clear, one can violate this doctrine in a number of ways--but mostly by not having clear goals and/or by not using decisive force. Rumsfeld and Franks violated the second part by sending as small a force as possible to Iraq in 2003.
The problem with the Powell doctrine was how it defined the goal of the use of force to achieve military and not political ends. I am a Clausewitzian, so there is no use of force without politics. The question is, rather, how can the use of military force affect the politics of a situation. The surges in Iraq and Afghanistan illustrated this quite well: the idea was to use more force to create a bit of momentum and a breathing space in which politics might be able to work out BUT that the surges themselves would not provide a political outcome that resolved the conflict.
Which gets us back to Iraq today: how does providing more force get us to a desirable outcome? So far, giving more help to Iraq has not made it less dependent on Iran and has not made it any more willing to credibly commit to providing political access to the Sunnis. Without that, there is no victory. As long as the political calculations of elites in Baghdad conflict with what the US wants, adding more troops or escalating is not going to improve things much.
The funny thing is that the place where politics is supposed to be taken most seriously, the State Department, seems to be the one where sunk costs logics are overwhelming reason:
The key is to figure out what American goals are and then figure out how force can or cannot play a role. If it is about degrading and containing ISIS, then maybe more force could be useful. But if it is about defeating it, well, that requires political changes in Iraq, which American soldiers simply cannot foster. Getting the politics right is the key, and it is why the last couple of wars have been so endlessly frustrating. The local actors simply do not have the same interests as the external ones.@smsaideman State in this instance = S/CT and INL who have billions tied up in kind items supporting Iraqi police, civic pgrms— Robert Caruso (@robertcaruso) June 14, 2015