This book provides an in-depth examination of the technological, geopolitical and normative pressures driving the world into a new, more complex and potentially more dangerous Third Nuclear Age. By adopting an innovative framework for analysis, the book challenges the constrained focus of much of the existing literature by explaining that the pathways to nuclear security for different actors across the globe will vary considerably in this new context. It argues that the Third Nuclear Age will be defined by friction and conflict between “Nuclear Traditionalists,” “Technological Transformers,” “Hedgers and Balancers,” and “Activists and Protestors,” as different interests and visions of the nuclear future clash. The book draws on dozens of interviews and non-English language sources to provide a global approach and looks at the security politics driving the political debate in 20 different countries across the globe. This book will be of much interest to students of nuclear politics, security studies and International Relations. The Open Access version of this book, available at www.taylorfrancis.com, has been made available under a Creative Commons Attribution-Non Commercial-No Derivatives (CC-BY-NC-ND) 4.0 license.