This chapter introduces the core research questions. How does a state’s relational web of support in the form of security assistance (amity) influence its relationships of threat (enmity)? How does a state’s relational web of enmity influence its relationships of amity? These questions pertain to many salient conflicts of our time. The chapter considers the ubiquity of proxy wars, recognizing that most conflicts are embedded in broader networks of support and threat relationships. It also explores the case of security assistance from the US and ponders the challenges for the US in maintaining a big-tent order. Key theoretical concepts are defined, and the chapter briefly summarizes the book’s arguments and findings. Finally, the chapter introduces the major cases used to illustrate and probe the limits of the arguments throughout the book: proxy wars in late–Cold War Southern Africa and Central America as well as contemporary dynamics in the Indo-Pacific.