North Korea’s leader, Kim Jong Un, started 2023 with a January 1 missile launch and kept at it throughout the winter. This followed record-breaking 2022 North Korean missile tests and demonstrations, which totaled approximately 70 launches of around 100 projectiles.
Given the near-zero prospects for North Korean denuclearization and the growing arsenal at Pyongyang’s disposal, it is understandable that any South Korean president would be focused on Korean Peninsula security issues.
The audacious nature of Yoon Suk Yeol’s refocusing on South Korean security—following attempts to broaden Seoul’s global influence—was surprising and controversial, however.
On January 11, apparently fed up with perceived South Korean vulnerability to its nuclear-armed consanguine, and perhaps irritated with the Joe Biden administration’s slow realization of this South Korean sentiment, Yoon made a pronouncement that no democratic leader in Seoul had ever made publicly before:
He stated that South Korea – which benefits from US extended nuclear deterrence – could still consider acquiring its own nuclear weapons, if “North Korean provocations continue intensifying.”
This set off a diplomatic kerfuffle that has resonated on both sides of the 38th parallel, as well as in Washington and Beijing.
Given the provocative nature of Yoon’s statement, the South Korean presidential office later backtracked, “clarifying” that Yoon was simply expressing his “firm commitment to defending the nation” against North Korea’s nuclear threats, and that while the “worst case scenario must be taken into consideration,” “the principle of abiding by the [Nuclear] Nonproliferation Treaty holds.”
In any event, Washington took notice of its anxious ally, responding with demonstrations of commitment to extended deterrence for South Korea – including a visit by Secretary of Defense Lloyd Austin and strategic asset deployments to South Korea.
All this was in addition to regular combined military exercises and naval exercises featuring US aircraft carrier strike groups. Washington also consented to more bilateral consultation with Seoul regarding the US nuclear umbrella.
The saga concluded – at least for the present – with the Washington Declaration promulgated at the Biden-Yoon summit in late April.
The declaration promises tightened US-South Korea extended deterrence coordination and consultation, while the leaders’ summit – in the context of Yoon’s state visit to celebrate 70 years of US-South Korea alliance relations – functioned as a renewal of Washington-Seoul ties.
These ties are now perhaps as strong as they ever have been. If Pyongyang reckoned that increased belligerence would decouple the US-South Korea alliance, it seemingly miscalculated.
Long confined to the loony fringe, South Korean conservative rhetoric advocating nuclear weapons development has gone mainstream in 2023.
South Korea has had – and perhaps still has – legitimate questions and concerns about the credibility of US extended deterrence in the face of North Korea’s growing nuclear weapons arsenal. The North now can strike continental US targets – thus complicating and injecting uncertainty into a potential US decision to retaliate with nuclear weapons in the event of a North Korean nuclear attack on South Korea.
These questions and concerns – clear in elite conservative political discourse – explain most of the rhetoric supporting South Korean development of an independent nuclear deterrent.
There are elements of desire for (inter)national prestige and worry about the need to hedge against rising China built into the pro-nuclear weapon discussion in South Korea. But what seemingly motivates South Korea’s conservative political elites to broach “going nuclear” is a perceived lack of US reassurance vis-à-vis the North Korean nuclear threat.
Domestic political opportunism presumably also plays a role, as some South Korean conservative politicians have – perhaps incorrectly – interpreted high popular support (60-70%) for South Korean nuclear weapons as (a) stemming from a lack of US extended deterrence credibility, and thus (b) a ground for shoring up political support ahead of 2024 general elections.
After Yoon’s crossing of the nuclear Rubicon during his January 11 presser, Hong Joon-pyo, a veteran heavyweight in the conservative People Power Party (PPP), indicated support for the president’s position.
Also in mid-January, Seoul mayor Oh Se-hoon, a star conservative, argued for South Korean nuclear weapons. Oh intensified that stance in a high-profile March interview with Reuters in which he called for South Korean nuclear weapons even in the face of costs and risks from international opprobrium (sanctions, strained diplomatic ties, etc).
A national assemblyman and former chairperson of the PPP, Chung Jin-suk, broached South Korean indigenous nuclear weapons in late February. North Korean defector and current South Korean National Assemblyman Thae Yong-ho has been on the record multiple times calling for South Korean nuclear weapons.
Whether intended or not, this dam-break in loose nuke talk accelerated, broadened and deepened attempts by Washington to enhance extended deterrence (in fact this was already underway in 2022 with the revived Extended Deterrence Strategy and Consultation Group).
The initial Biden administration response to the outbreak of nuclear armament discussion in early 2023 seemed to focus on deterrent capabilities: air warfare training featuring F-35s, F-22s, B-52s, and B1Bs; aircraft carrier strike group visits to exercise with South Korean naval units; increased trilateral exercises (including on missile defense) with Japan.
But the crux of South Korea’s anxieties does not concern capabilities, about which there is no doubt in Seoul or Pyongyang. The real issue is reassurance, which is ultimately a question of political will.
Consequently, Washington decided to offer Seoul greater possibilities for US-South Korea extended deterrence consultations, and to institute joint nuclear-focused table-top exercises that could give South Korean officials and officers better insight into US nuclear-use decision-making for extended deterrence.
With the subject of South Korea’s independent nuclear deterrent still alive in April, during the lead-up to President Yoon’s state visit to Washington, DC and accompanying summit, US National Security Advisor Jake Sullivan was foreshadowing “major deliverables” on extended deterrence.
That turned out to be the Washington Declaration, which commits the alliance to “deeper, cooperative decision-making on nuclear deterrence, including through enhanced dialogue and information regarding growing nuclear threats to the ROK and the region.”
To this end, the Washington Declaration establishes the Nuclear Consultative Group (NCG), which institutionalizes a high-level consultation mechanism enabling South Korea to better understand US policy, posture and logic regarding nuclear use in an extended deterrence context, and on that basis to communicate Seoul’s position.
The Washington Declaration also institutionalizes the table-top simulations mentioned above and promises regular “visible” strategic asset deployments on and around the Korean Peninsula, starting with the first US nuclear ballistic-missile submarine (SSBN) port call in South Korea since 1981.
The quid pro quo was Seoul’s reiteration of dedication to the Nuclear Nonproliferation Treaty, effectively quieting the South Korean indigenous nuclear weapon debate.
Whether it remains quiet is likely, in the short-to-medium term, to depend on the quality, personnel-rank level, rhythm, momentum and effectiveness of NCG meetings, as well as the identity of the occupant of 1600 Pennsylvania Ave on January 20, 2025.
Another factor will be the connection of the incipient South Korean conventional Strategic Command with the capabilities and planning of US-South Korea Combined Forces Command, and, by extension, to the US Strategic Command.
In the long term, South Korea’s satisfaction with extended deterrence is likely to depend on the interplay of North Korea’s nuclear arsenal advancement or rollback and the evolution of the NCG toward a status similar to that of NATO’s Nuclear Planning Group. (One notes that the US has pointedly denied that the NCG could morph into a NATO-style nuclear-sharing arrangement.)
If Pyongyang’s nuclear weapons growth goes unchecked, or if the NCG fails to progress, the Washington Declaration will end up a temporary band-aid on South Korean desires for nuclear weapons. Indeed, the conservative media in South Korea were critical of the Washington Declaration and NCG even before Yoon landed in Seoul after his trip to Washington.
Mason Richey is an associate professor at Hanguk University of Foreign Studies in Seoul. This article, abridged from one originally published by the Pacific Forum in Honolulu, is extracted from Comparative Connections: A Triannual E-Journal of Bilateral Relations in the Indo-Pacific, Volume 25, Number 1, May 2023, is republished with kind permission.