(Non)intervention in intra-state conflicts

There are two factions in a conflict. A third party may choose to intervene by supporting one of the factions. We consider a third party maximizing a weighted sum of the welfare of the warring factions and the non-combatant population. The third party's intervention decision is influenced by the nature of the conflict success function, the difference in ability between the combatants, his belief of how protracted the conflict will be in the absence of intervention, the weight he places on the welfare of the combatants relative to the rest of the population, and whether he can intervene militarily or non-militarily. Under certain conditions, the third party intervenes for sufficiently extreme values of the weight placed on the warring factions but does not intervene for intermediate values.