Bicchieri (The grammar of society: The nature and dynamics of norms, 2006, xi) presents a formal analysis of norms that answers the questions of “when, how, and to what degree” norms affect human behavior in the play of games. The purpose of this paper is to apply a variation of the Bicchieri norms analysis to generate a model of norms-based play of the traditional deterrence game (Zagare and Kilgour, Int Stud Q 37:1–27, 1993; Morrow, Game theory for political scientists, 1994), the paradigmatic model of conflict initiation in International Relations. The deterrence game is modeled here as a sequential decision problem. As such, our analysis is an adaptation of Bicchieri’s game-theoretic formalization of norms to what we will call the norms account of the game. We find that the standard account of the traditional deterrence game is a special case of the norms account of the game. We also show that the adaptation of Bicchieri’s analysis of social norms yields new and interesting claims regarding when, how, and to what degree norms operate as a constraint on risk-related behavior in the traditional deterrence game. Moreover, we discuss how the results of the model provide testable propositions of relevance to the role of norms in international interactions.