This paper presents a model of strategic interaction in which a third party intervenes on behalf of a government in its conflict with insurgents. It examines whether it is better for the intervenor to adopt an input-based strategy (i.e., specify the total resources it will spend) or an outcome-based strategy (i.e., specify the goal that it will achieve), and it shows that outcome-based strategies are better for the intervenor than input-based ones if and only if in the absence of intervention the insurgents are stronger than the government. A system of benchmarks that are tied to the efforts of both parties outperforms both input-based and outcome-based strategies. Lessons from the theory are applied to U.S. strategy in Iraq.
Miller, Nolan. "Outcome Commitments in Third-Party Intervention: Theory and Application to U.S. Policy in Iraq." HKS Faculty Research Working Paper Series RWP08-041, September 2008.