Last month, South Korean President Yoon Suk-yeol warned that in the face of mounting North Korean provocations, South Korea might consider building its own nuclear weapons or asking the United States to deploy tactical nuclear weapons to the South, as it did during the Cold War. Although Yoon later stressed that his comments did not represent official policy, they were still significant—marking the first time that a South Korean president has raised the prospect of acquiring nuclear weapons since Washington withdrew its own nukes from the South in 1991.
Yoon’s comments are not the only indication that U.S. allies in East Asia are growing concerned about the credibility of Washington’s so-called extended deterrence commitments. These allies have little doubt that adversaries of the United States would think twice about attacking the U.S. homeland for fear of overwhelming retaliation; Washington is ably deterring that sort of aggression. They are increasingly uncertain, however, that U.S. deterrence extends to them. Would the United States honor its pledges to use the full range of U.S. capabilities, including nuclear weapons, to deter and, if need be, defeat external attacks on the territory and sovereignty of its allies?
