The actions states take toward one another are of primary importance in determining whether a rivalry will result in war. From their interactions, states learn that force and war are the only way of resolving the issue at hand. In this sense, interstate interactions can be viewed as one set of constraints in which the leadership of a state operates. The dynamics of the relationship close off certain possibilities, while encouraging other actions that will increase tensions. These interactions, however, do not take place in isolation; they interact with a second set of constraints, the domestic political context in which the leadership of each side must operate. This chapter will examine how external interactions produce those domestic consequences which encourage more hostile (and escalatory) steps to be taken within a rivalry and within a crisis.

Although various aspects of the causes of war have been researched by those taking a scientific approach to international relations, the domestic prerequisites have received little attention. Not much consideration has been given to how leaders try to mobilize a society for the decision to go to war or how the domestic political environment encourages a government to make, or restrains it from making, a foreign policy that is apt to lead to war.