Amid North Korea's advancing nuclear capabilities and the declining credibility of U.S. extended deterrence, South Korea has a strong motive to pursue its own nuclear deterrent. With its advanced nuclear energy program, South Korea possesses the means to develop nuclear weapons indigenously. However, its opportunity to do so is constrained by the prohibitive economic, security and reputational costs of nuclear armament. To circumvent these costs, Seoul is engaging in "nuclear hedging," pursuing the capability to develop nuclear weapons rapidly while stopping short of actual weaponization.   Drawing on Korean- and English-language documents, archival materials, and interviews with South Korean security experts, Lami Kim offers the most comprehensive analysis to date of South Korea's pursuit of nuclear hedging as an alternative to both nuclear restraint and outright nuclear armament. South Korea's renunciation of its nuclear weapons program in the 1970s—and its subsequent restraint—should not be mistaken for an absence of nuclear ambition grounded in confidence in U.S. extended deterrence. Instead, under both conservative and progressive governments, Seoul has sought the ability to acquire nuclear weapons rapidly, if necessary, as an insurance policy. A major contribution to the literature on nuclear deterrence, nonproliferation, and Korean studies, this book delivers timely and insightful policy recommendations for both Washington and Seoul.