North Korea’s nuclear, missile, and conventional forces are a formidable threat to the United States and its allies in northeast Asia. Pyongyang’s history of provocation and intimidation is a consistent indicator of the regime’s intent to achieve its political objectives through the threat of execution of force. Greater North Korean nuclear capabilities could undermine the effectiveness of existing allied military plans. Pyongyang could deter allied preemptive or retaliatory attacks, target U.S. forces arriving on the Korean Peninsula and allied forces preparing a counteroffensive advance into North Korea, and threaten the American homeland. Attaining an unambiguous nuclear ICBM capability could lead North Korea to perceive that conditions for reunifying the peninsula on its terms had become favorable. Pyongyang could feel emboldened to act even more belligerently and seek to intimidate the U.S. and its allies into accepting North Korean diktats. North Korea’s increasingly viable ability to target the continental United States with nuclear weapons exacerbates long-standing allied fears of abandonment and decoupling of alliances, encapsulated in the oft-cited phrase – “would the U.S. really trade San Francisco for Seoul?” While South Koreans repeatedly demand greater U.S. efforts at proving its commitment to defend its allies, deterrence is an allied responsibility and reassurance is a two-way street. Seoul must also take measures, including cooperation with Japan, to enhance allied deterrence and defense capabilities. The United States must ensure that it can protect the American homeland and U.S. forces in the Indo-Pacific region. Washington should coordinate with South Korea and Japan to improve comprehensive allied missile defenses. The United States and its allies must also have sufficient offensive capabilities to reduce the number of North Korean missiles that are launched.