I have tried, in the first four chapters, to provide a variety of useful items to go into our conceptual and theoretical toolbox. With that foundation, we will now move on to the first of four applications of the ways in which geopolitical approaches can help us understand international relations and international conflict and cooperation. In this chapter the toolbox will be applied to help us understand alliances through the broader context of geopolitics and geopolitical perspectives on international relations. Using the Sprouts’ ecological triad framework and the opportunity and willingness framework, alliances are viewed as part of the web of geopolitical constraints that affect possibilities in the international system. Alliances are viewed as part of the set of incentive structures that affect foreign policy decision making and as a central mechanism that permits decision makers to overcome the geopolitical constraints of the system. Drawing on analogies with technology and borders, alliances can be viewed as important tools for overcoming the constraints of geopolitics and for changing the meaning of the supposedly “permanent” nature of international geography.