| This dissertation asks why and under what conditions the US seeks allies for foreign military interventions and when multilateralism pays for a state with a unilateral option. It is not a study of whether to intervene or not, but rather the motivations and payoffs for hegemonic choices between unilateralism and multilateralism in post-Cold War US military interventions. By way of guiding that study, I evaluate several externally generated hypotheses---domestic politics, normative constraints, and regional power dynamics---and add one internally generated hypothesis---a state's time horizon and the operational payoff of multilateralism---theoretically. I then conduct detailed case studies and cross-case comparisons of the Gulf War, Haiti, Afghanistan, Iraq, as well as three negative cases---Bosnia (1992-95), North Korea (1994), and Rwanda (1994)---to test the hypotheses and assess causal arguments.While domestic politics and regional power dynamics explain some of the variation between unilateralism and multilateralism in post-Cold War interventions, I find the most support for the internally generated hypothesis. In this I argue that (1) how immediately state interests are threatened or the costs of not acting quickly (time horizon) and (2) the potential benefits associated with multilateral burden-sharing create a set of incentives and constraints that determine whether a state with a unilateral option such as the US is likely to pursue an intervention multilaterally. This logic finds strong support from the case studies and is most likely to dominate behavioral outcomes when its analytical predictions diverge from those of the alternative hypotheses.This research helps mediate both theoretical and policy debates on US cooperation behavior. It first addresses the more theoretical question of whether choices of unilateralism are a function of US power or rather whether other factors are better predictors of US decisions to circumvent multilateral channels and intervene unilaterally. It also addresses the policy debate of whether and when multilateralism pays for a state with a unilateral option for intervention. I conclude that unilateralism is not a temptation of unipolarity because of the enduring incentives to intervene multilaterally, and that as a result, any rumors of multilateralism's demise may have been highly exaggerated. |
