There is no shortage of plausible scenarios describing North Korean regime collapse or how the United States and North Korea's neighbors might respond to such a challenge. Yet comparatively little attention has been paid to the strategic considerations that may shape the responses of the United States, the Republic of Korea (ROK), Japan, China, and Russia to a North Korean crisis. These states are most likely to take action of some kind in the event the North Korean regime collapses. For the ROK (South Korea), North Korean regime collapse presents the opportunity for Korean reunification. For the other states, the outcome in North Korea will affect their influence on the peninsula and their relative weight in Asia. This study identifies the interests and objectives of these principal state actors with respect to the Korean Peninsula. Applying their interests and objectives to a generic scenario of North Korean regime collapse, the study considers possible policies that the principal state actors might use to cope with such a crisis. The goal of this study is to motivate policymakers to consider how the United States would respond to regime collapse, not to identify the most plausible scenario. It is the precrisis planning process that is necessary in order to develop a comprehensive understanding of the issues, choices, and priorities that will challenge U.S. diplomacy in the event of North Korean regime collapse. In particular, Washington must plan for the likelihood that while the United States and South Korea will seek to be the primary actors in a crisis induced by North Korean regime collapse, the actions of China and North Korea will profoundly influence U.S. decisions and room to maneuver. The United States will also need to gain the cooperation of Japan and Russia, as well as the support of the United Nations, to achieve politically acceptable outcomes.

The United States has no good options for resolving the North Korean and Iranian nuclear challenges. Incentives, pressures, and threats have not succeeded. A military strike would temporarily set back these programs, but at unacceptable human and diplomatic costs, and with a high risk of their reconstitution and acceleration. For some policymakers, therefore, the best option is to isolate these regimes until they collapse or pressures build to compel negotiations on U.S. terms. This option has the veneer of toughness sufficient to make it politically defensible in Washington. On closer scrutiny, however, it actually allows North Korea and Iran to continue their nuclear programs unrestrained. It also sacrifices more achievable short-term goals of improving transparency and securing vulnerable nuclear materials to the uncertain long-term goal of denuclearization. Yet these short-term goals are deemed critical to U.S. national security in the 2010 Nuclear Posture Review (NPR) and Quadrennial Defense Review (QDR). North Korea and Iran are very different states that share at least one crucial similarity: decades of estrangement from Washington and U.S. efforts to isolate them from the international community. They also play destabilizing roles in the regions they inhabit, lack respect for basic democratic freedoms, and maintain policies antagonistic to the United States, its friends, and its allies. It is hardly surprising that the Washington consensus still supports isolation. What is striking, however, is the pronounced international consensus in favor of engagement, which sharply constrains an already limited U.S. policy arsenal. Assessing two decades of nuclear diplomacy with North Korea and nearly a decade of efforts with Iran, it is clear that Washington needs a more promising strategy. Nothing short of a paradigm shift away from denuclearization is required to alter the pattern of bad outcomes in both cases. The new paradigm, predicated on strong bipartisan support, would recognize the national security advantages of a negotiated nuclear pause as a prelude to denuclearization. Allowing North Korea and Iran to retain their current nuclear capability would give them an important incentive to cooperate with international monitoring aimed at improving the transparency of their nuclear programs and capabilities, and securing vulnerable nuclear materials-the goals identified by the NPR and QDR as vital to national security. Denuclearization would remain the publicly declared-and indeed desired-endstate of negotiations, but an outcome requiring a long time horizon to achieve. In the meantime, a nuclear pause diminishes the risk of further nuclear advances by these states and brings North Korea and Iran "inside the tent" through international monitoring. It also buys time to develop new policy mechanisms to further contain their programs. More crucially, it could open up political space in both states for moderation overall, including accommodation (vice defiance) of international demands, especially on the nuclear issue. This comparative study of U.S. nuclear diplomacy toward North Korea and Iran suggests that the North Korea case offers policymakers crucial lessons applicable to Iran. It provides policy recommendations based on four key conclusions: that a common paradigm (nuclear pause) must be applied to both states; that nuclear deals negotiated with international outliers like North Korea and Iran must draw on widely accepted policy or practice; that these deals should be linked to political/diplomatic strategies relevant to the domestic and regional policy context of each state; and that the success of a nuclear pause must be judged by whether it accomplishes nuclear policy goals, not broader policy goals. Time is of the essence. North Korea's leadership transition could prove destabilizing to the region, and Iran's enrichment capability is steadily advancing.

The Institute for National Strategic Studies (INSS) is National Defense University's (NDU's) dedicated research arm. INSS includes the Center for Strategic Research, Center for Complex Operations, Center for the Study of Chinese Military Affairs, Center for Technology and National Security Policy, Center for Transatlantic Security Studies, and Conflict Records Research Center. The military and civilian analysts and staff who comprise INSS and its subcomponents execute their mission by conducting research and analysis, publishing, and participating in conferences, policy support, and outreach. The mission of INSS is to conduct strategic studies for the Secretary of Defense, Chairman of the Joint Chiefs of Staff, and the Unified Combatant Commands in support of the academic programs at NDU and to perform outreach to other U.S. Government agencies and the broader national security community.