Book excerpt: Defence Industries in the 21st Century explores the transformation in the global defence industrial production through examining the interaction between international and domestic factors. With the global defence industry and arms market likely continue to expand and mature, the ways in which this progression could influence international politics remain obscure. In practice, as the contents of this book show, the defence industrial bases and arms export policies of emerging states display significant variance. This variance is the result of a unique balance between domestic and international factors that has shaped the defence industrialisation behaviour and policies of the less industrialised states. One of the most important conclusions of the book is that the interplay between domestic and international factors clearly influences the variation in the emerging states’ defence industrialisation policies, as well as their success or failure. While international factors create opportunities, they also limit the options available to emerging economies. Domestic factors also play an important role by shaping the policy choices of the states’ decision makers. Exploring the balance between international and domestic factors and the ways in which they influence defence industrialisation in emerging states, Defence Industries in the 21st Century will be of great interest to scholars of Defence Industries, Arms Manufacturing, and Defence, Strategic and Security Studies more generally. The chapters were originally published in Defence Studies, Comparative Strategy and All Azimuth.