ABSTRACT
Military alliances have been an enduring and recurrent phenomenon throughout history. The scholarship on military alliances has been a source of theoretical innovation, has provided insights into understanding the dynamic of international politics across time and space, and has informed the policy choices of great and small powers alike. This chapter considers sequentially four themes that have emerged in the vast literature on military alliances: the systemic and unit-level imperative(s) for alliance formation; the categorization of alliances in terms of stability, credibility, and system-type; the benefits and costs of alliance formation; and the factors contributing to alliance cohesion and disintegration. The chapter concludes with a discussion of alliances as instruments of collective securitization in the contemporary international system.
