War, implementation costs and minimal winning coalitions

Riker's theory of the minimal winning coalition has found relatively little use in explaining international alliances. One reason for this is that international alliances, unlike coalitions in political systems which have established authority structures, must bear the cost of implementing decisions. In so doing they may be liable to great costs (e.g., money, casualties), and efforts to reduce these costs may result in the expansion of the coalition beyond minimal winning size. The utility of implementation costs as an addition to Riker's theory is illustrated in a case study of American attitudes toward the entry of the Soviet Union into the war against Japan.