Amid warnings that “the end of the world is only 89 s away” and Russia’s frequent threats to use nuclear weapons, one of the most alarming and unpredictable threats to global security is North Korea’s nuclear armament and aggressive posture. North Korean leaders appear to believe that by acquiring intercontinental ballistic missiles capable of striking the U.S. mainland, they can undermine the credibility of U.S. nuclear extended deterrence for South Korea. Operating under this belief, they have openly threatened nuclear attacks on—and the annexation of—South Korea. Furthermore, North Korea has effectively revived its Cold War-era alliance with Russia, formalizing a strategic partnership and dispatching military personnel to support Russia’s war in Ukraine. Existing deterrence theories and policies have demonstrated significant limitations in accounting for North Korea’s increasingly provocative nuclear buildup and aggressive maneuvers. Against this backdrop, serious discussion is required on the critical issues raised by North Korea’s nuclear buildup, including the disruption of the global nuclear balance, the erosion of nonproliferation norms, and the growing challenges to traditional deterrence theory.