His specialization is applied mathematics. His research interests are split between theoretical mechanics and international relations. In the latter area he has focused on the development and study of models of international conflict, with work published in the Journal of Conflict Resolution, Synthese, and the Journal of Theoretical Politics. More recent work is concerned with models of the inter-nation network of friendship and enmity, and the impact of this network on sequences of disputes. In addition he is exploring ways in which dynamic models, especially those concerned with arms races, can be given a game theoretic foundation. Current interests are in evolutionary game theory and its uses in studying security as a public good.