This book chronicles the political-military development of the Korean Peninsula since 1945, with particular attention to North Korea's pursuit of nuclear technology and nuclear weapons, and how it has shaped Northeast Asian security and non-proliferation policy and influenced the strategic choices of the United States and all regional powers. I focus on North Korea's leaders, institutions, political history, and the system's longer-term prospects. How has an isolated, highly idiosyncratic, small state repeatedly stymied or circumvented the policy preferences of much more powerful states, culminating with its withdrawal from the Non Proliferation Treaty (the only state ever to do so) and the testing of nuclear weapons in open defiance of adversaries and allies alike? What does this portend for the region's future? Unlike most of the literature that focuses on US non proliferation policy, this is a book about decision making in North Korea and the state's survival in the face of daunting odds. It draws on extensive interviews with individuals in China, South Korea, Japan, Russia, and the EU who have had ample experience in and with North Korea, additional interviews with former US policy makers, and the results from two visits to the North. The author makes extensive use of archival materials from the Cold War International History Project, enabling a far fuller rendering of North Korean history than appears in most of the literature on the North Korean nuclear weapons issue.