OPINION:
President Biden and South Korean President Yoon Suk Yeol signed a bilateral nuclear agreement on April 26 that addressed U.S. concerns about allied nuclear proliferation and South Korean doubts of the viability of the American extended deterrence guarantee. How durable will this agreement prove to be?
The Washington Declaration was a response to a surge in South Korean advocacy for an indigenous nuclear weapons program or redeployment of U.S. tactical weapons to the Korean Peninsula. Both nations attained their objectives, but the accord could be undermined by either the escalating North Korean threat or the vicissitudes of American policies.
South Korea’s new nuclear advocacy was driven by several factors. The most obvious is North Korea’s escalating nuclear and missile threats. But there are also increasing doubts about whether the U.S. would risk nuclear attacks on its cities by North Korean ICBMs in defense of South Korea.
In addition, there is concern that a future isolationist U.S. administration could seek to degrade the bilateral alliance, as well as injured South Korean national pride at not having the nuclear status of some U.S. allies in Europe.
Nongovernment experts were most strident in pushing for an indigenous nuclear program, arguing that the United States would never fulfill its treaty obligations to defend South Korea if it risked American cities. Public polling showed strong domestic support, but responses were less positive when the consequences to South Korea of a nuclear program were explained.
The South Korean government repeatedly affirmed it didn’t seek any nuclear options but instead sought strengthened extended deterrence from the United States. Mr. Yoon was a wild card, several times suggesting support for nuclear options, only to have him or senior officials quickly walk back such statements.
In any case, South Korean officials were frustrated by a perceived U.S. lack of transparency on nuclear policy and sought greater involvement in nuclear planning and operations, possibly commensurate with NATO nuclear-sharing arrangements. Washington was reluctant to divulge sensitive nuclear information but, responding to growing South Korean government concerns and public nuclear advocacy, undertook a monthslong initiative to prevent a crisis in the alliance.
Washington increased nuclear information-sharing, enhanced bilateral consultations, initiated tabletop exercises that included North Korean nuclear-use scenarios, and escorted South Korean delegations to nuclear bomber and submarine bases. By the time of the presidential summit, South Korean officials privately expressed much greater confidence in the U.S. extended deterrence guarantee than at the beginning of the year.
In the Washington Declaration, the United States agreed to a new bilateral Nuclear Consultative Group, pledged to consult with South Korean leadership on use of nuclear weapons on the Korean Peninsula, and to enhance nuclear information-sharing, planning, exercises and cooperative decision-making. While not guaranteeing U.S. use of nuclear weapons in response to North Korean nuclear use, Washington affirmed that such North Korean action would lead to the end of the regime.
In return, South Korea affirmed its commitment to the Non-Proliferation Treaty and the bilateral U.S.-South Korean civilian nuclear agreement, as well as declaring its “full confidence in U.S. extended deterrence commitments,” thus firmly closing the door on an indigenous nuclear weapons program. Seoul also agreed to coordinate, if not indirectly integrate, its new Strategic Command with the U.S.-South Korean Combined Forces Command.
The Washington Declaration is focused more on enhancing reassurance to Seoul than increasing deterrence to Pyongyang. Last year, the U.S. and South Korea resumed large-scale conventional military exercises, repairing the degradation to alliance military readiness wrought by the unilateral 2018 U.S. decision to cancel and constrain combined exercises. Washington and Seoul announced they would increase military exercises this year, including at least 10 large-scale exercises.
In 2022, Washington also resumed rotational deployment of nuclear-capable strategic assets after a four-year hiatus, to enhance alliance deterrence against North Korea and reassure South Korea of America’s commitment. In 2022-23, the U.S. deployed strategic bombers, dual-capable fighter aircraft, submarines and aircraft carriers to the Korean Peninsula. Mr. Biden pledged to further enhance the regular visibility of strategic assets including the first visit of a ballistic missile submarine to a South Korean port in 40 years.
The Yoon administration achieved its objective of a more prominent voice in U.S. nuclear decision-making, and the bilateral alliance now includes a formalized nuclear role for South Korea. The extent of the change is unclear, but it’s unlikely to be publicly delineated given the sensitivity of discussion nuclear strategy. The U.S. president will retain full authority over the use of U.S. nuclear weapons; South Korean officials won’t be involved in nuclear targeting.
South Korean nuclear advocates will criticize the Washington Declaration since they seek nothing less than a full-fledged indigenous nuclear weapons program, regardless of the consequences for South Korea. While Mr. Yoon may have previously appeared to be on their side, it is now clear that he opposes a nuclear option. As such, advocates will now be swimming upstream to overturn government policy.
Less certain is the degree to which the South Korean public will embrace the new agreement with Washington. The Yoon administration will need an effective strategic messaging program to convince the populace that greater integration with the U.S., not an independent nuclear program, is better for South Korean national security.
Going forward, South Koreans will remain nervous over North Korea’s growing nuclear and missile arsenal, the regime’s escalating provocative behavior, and uncertainty over the future dependability of its American ally. Washington will need to show progress in incorporating South Korea into its nuclear planning to prevent another crisis in credibility.
• Bruce Klingner is senior research fellow for Northeast Asia at The Heritage Foundation and previously served as the CIA deputy division chief for North Korea.
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