During a state visit to Washington to mark the seventieth anniversary of the U.S.-South Korea alliance, the Joe Biden and Yoon Suk-yeol administrations have addressed head-on the immediate issue most likely to generate cracks in the alliance. That issue is the question of the credibility of U.S. pledges to defend South Korea from North Korean threats to use nuclear weapons against either the United States or South Korea to perpetuate regime survival.
The combination of North Korean threats of preemptive attack using tactical nuclear weapons and its ongoing expansion of missile capabilities have heightened a sense of vulnerability among South Koreans around its dependence on the United States for defense and retaliation against possible North Korean nuclear use. In response, Presidents Biden and Yoon have issued the Washington Declaration.
The declaration opens the door to the establishment of a Nuclear Consultative Group (NCG) between the governments of the United States and South Korea, modeled on nuclear consultations within NATO. The establishment of this group extends, to the nuclear realm, the principle of joint response that already exists with the Combined Forces Command, through which U.S. and South Korean military forces work every day to deter a conventional attack.
Through this group, the United States and South Korea would engage in joint planning and implementation of responses to North Korean nuclear use. The establishment of a nuclear consultative mechanism would presumably give South Korea a greater voice in preparations surrounding nuclear retaliation while the United States would retain control over the nuclear weapons themselves.
The declaration also reaffirms South Korea’s intention to stay in the Nuclear Nonproliferation Treaty (NPT), indirectly pledging not to pursue an independent nuclear weapons capability. In this respect, the Yoon administration is pledging to set aside the prospect that South Korea would develop and deploy an independent nuclear weapons capability in favor of a robust alliance-centered response. Such an approach enhances the likelihood that North Korean efforts to provoke differences between the United States and South Korea due to its continued military advances, which could lead to the dissolution of the U.S.-South Korea alliance, will be unsuccessful.
The pledges contained in the Washington Declaration are credible and convincing, but the biggest question is whether it will prove to be durable. In this respect, the Washington Declaration and the establishment of the NCG faces two primary challenges.
The first challenge is the ability of the envisioned NCG to stay ahead of future North Korean military developments. North Korea has persistently and deliberately expanded its missile capabilities and types of platforms available to deliver nuclear weapons, as well as extend the range, speed, and credibility of its missile delivery capabilities. The U.S.-South Korea NCG must demonstrate a capability to stay ahead of North Korea’s military advancements. Thus, the priority following the declaration should be on the swift creation and implementation of the joint response mechanism.
A second challenge to the credibility of the Washington Declaration is the ability of the two governments to sustain visible efforts in strengthening deterrence against North Korea even after the summit afterglow has faded. The Biden administration will return to other concerns including the war in Ukraine, the competition with China, and U.S. domestic politics and policies. The Yoon administration will face its own domestic and foreign political challenges. Despite these competing priorities, the South Korean public will require political assurance that the resolve present during the announcement of the Washington Declaration continues day after day. That is why the U.S. task of providing political assurances requires constant attention and exertion of political will at the leadership level, even alongside the establishment of stronger nuclear consultation mechanisms with South Korea.