Vulnerable US Alliances in Northeast Asia: The Nuclear Implications

Despite rising threats and challenges in Northeast Asia, the US commitment to its allies there has become less certain. In part, this is by design. President Trump argued that less categorical signals would encourage US allies to do more, either in their own defense or to support (and finance) forward deployed US forces. Hearing this, Japanese and South Korean (ROK) leaders have been led to consider alternatives to the status quo. They increased defense budgets, a welcome development in Washington, but they also have taken measures that may complicate alliance dynamics, undermine crisis stability, and weaken the broader project of balancing Chinese power. Early in his term, President Biden pledged to improve alliance relations. But confronted with uncertainty, Japan and Korea continue to edge toward offensive systems, including missile forces, which may prove destabilizing in crises. They have also moved away from the rolesand missions-based specialization of military labor that has enhanced alliance efficiencies for decades. The widening discussion of nuclear weapons in both countries is perhaps most striking. While nuclear breakout could strengthen Japanese and South Korean self-defense, it would not necessarily enhance balancing. Indeed, given the