NUCLEAR WEAPONSOptions for Strengthening South Korea’s Nuclear Assurance

North Korea has been vastly increasing its nuclear weapon threat and plans to accelerate this process in the future. North Korea has also adopted an extremely hostile campaign of threatening the Republic of Korea (ROK) and the United States with nuclear attacks. China is also vastly increasing its nuclear weapon capabilities and is no longer trusted by most people in the ROK.

A new report from RAND says that to counter these threats, the United States provides extended deterrence for the ROK and promises a nuclear umbrella to cover the ROK so that the ROK does not need its own nuclear weapons. The United States wants a nuclear weapon–free Korean Peninsula to avoid imperiling the Nuclear Non-Proliferation Treaty, the foundation of U.S. nuclear nonproliferation policy. The United States has constructed its nuclear umbrella on a high degree of strategic ambiguity in the belief that this ambiguity will achieve the most-effective deterrence of North Korean aggression.

But this ambiguity, the growing North Korean threat, and U.S. withdrawal from other allied countries (e.g., Afghanistan) have caused many in the ROK to question the existing U.S. commitment and seek more-concrete assurance. Sensitive to this concern, President Joe Biden supported ROK President Suk Yeol Yoon with the Washington Declaration in April 2023. This report proposes options that the United States and the ROK could exercise to strengthen ROK nuclear assurance consistent with the Washington Declaration, including enhancing strategic clarity, coercing North Korea to freeze its nuclear weapons, and committing U.S. nuclear weapons to support the ROK.

Key Findings

·  North Korea has a nuclear weapon force that may already pose an existential threat to the ROK and is on the verge of posing a serious threat to the United States. The North hopes to use its nuclear weapon threats to help break the ROK-U.S. alliance.

·  China poses very serious nuclear weapon threats to the ROK and the United States.

·  ROK assurance in the U.S. nuclear umbrella has faltered because of these growing threats and the ambiguity in the U.S. commitment to ROK security, leading to calls for ROK development of nuclear weapons.

·  Because of these developments, the U.S. nuclear umbrella requires greater strategic clarity for both deterrence and ROK assurance.

·  The Washington Declaration promises greater strategic clarity. However, it needs greater implementation details to increase ROK nuclear assurance.

·  The United States could pursue strategic clarity akin to the efforts taken with the North Atlantic Treaty Organization in the 1960s.

·  A ROK-U.S. coercive campaign to freeze North Korean nuclear weapon development could strengthen ROK nuclear assurance.

·  The United States could commit U.S. nuclear weapons to establish some level of parity against the North Korean nuclear weapon threat to the ROK. Doing so might avoid a future decision by the ROK government to produce its own nuclear weapon force.

·  ROK nuclear weapon production could lead to international sanctions on the ROK that would seriously damage the ROK economy, cause political controversy and instability, and increase global nuclear weapon proliferation.