What determines US humanitarian intervention?

Why does the United States as a third party intervene abroad in responding to humanitarian crises? While liberals argue that the purpose of an intervention is to protect victims of human rights violations, realists contend that interventions have little relation to humanitarian concerns and aim, instead, at certain national interests such as securing an oil supply. Making scientific progress, in explaining the determinants of US humanitarian intervention, requires confronting these theoretical positions with data. Drawing on a cross-national, time-series data analysis of 153 countries for the years 1981–2005, the quantitative research presented in this study is the first of its kind to evaluate the relative importance of these competing theoretical perspectives. After controlling for other variables such as democracy and media coverage, this study finds evidence that the United States is likely to use force in a manner consistent with the theory put forth by liberals. This finding indicates that US humanitarian interventions are utilized for the purpose of preserving liberal norms and moral values rather than for pursuing national interests.