[Commentaire du GNI] Des relations basées sur les avantages mutuels : La République de Corée peut-elle compter sur la dissuasion nucléaire étendue des États-Unis ?

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Editor's Note

The extended nuclear deterrence provided by the US aims to protect South Korea from a third-party aggressor such as North Korea. However, there are issues related to the provider’s credibility and reliability. In this commentary, Professor Mason Richey, associate professor of international politics at Hankuk University of Foreign Studies, examines whether South Korea should continue to rely on US extended nuclear deterrence by considering the status of the current US-ROK alliance. Professor Richey suggests three “mutually reinforcing paths” including strengthening South Korea’s conventional deterrence capabilities, initiating a Korean Peninsula Nuclear Planning mechanism, and having South Korea take post-US presidential election measures to improve relations with the US. As much as Seoul’s national security depends on Washington, US domestic political factors affect South Korea’s security. In this regard, the upcoming US election may provide a crossroad for the US-ROK alliance. Professor Richey argues that alliance recovery will be easier if Biden gets elected since his administration’s priority is to repair US alliances.

The extended nuclear deterrence provided by the US aims to protect South Korea from a third-party aggressor such as North Korea. However, there are issues related to the provider’s credibility and reliability. In this commentary, Professor Mason Richey, associate professor of international politics at Hankuk University of Foreign Studies, examines whether South Korea should continue to rely on US extended nuclear deterrence by considering the status of the current US-ROK alliance. Professor Richey suggests three “mutually reinforcing paths” including strengthening South Korea’s conventional deterrence capabilities, initiating a Korean Peninsula Nuclear Planning mechanism, and having South Korea take post-US presidential election measures to improve relations with the US. As much as Seoul’s national security depends on Washington, US domestic political factors affect South Korea’s security. In this regard, the upcoming US election may provide a crossroad for the US-ROK alliance. Professor Richey argues that alliance recovery will be easier if Biden gets elected since his administration’s priority is to repair US alliances.

The logic of and motivation for extended nuclear deterrence are clear. The extension of the US nuclear umbrella to South Korea is intended to deter North Korea (and possibly other states such as China and Russia) from launching a nuclear attack on South Korea. This aims to promote stability in the East Asia region. It reduces South Korea’s incentive to develop an independent nuclear deterrent, helping prevent a proliferation arms race among neighboring states seeking their own paths of nuclear breakout. Moreover—and arguably more importantly—US extended nuclear deterrence for South Korea is intended to increase conventional deterrence as well, as Washington’s nuclear backstop for Seoul in theory disincentivizes[1] Pyongyang from launching a major[2] conventional attack for fear that it could escalate to an unwinnable nuclear conflict.

The logic of extended nuclear deterrence may be clear, but there always lingers the question of the credibility and reliability of the provider of extended nuclear deterrence. This is true both in general and in the particular case of the Korean peninsula.

US extended nuclear deterrence for South Korea is central to the security of both the Korean peninsula and East Asia writ large, yet is politically fragile. Hence the question: should South Korea count on US extended nuclear deterrence? This article examines the question from several perspectives, notably in light of strategic considerations and the current state of the US-ROK alliance.

Casting Doubt

If the conceptual logic of extended nuclear deterrence is clear, the willpower to execute its fundamental underpinning—launching a US nuclear strike against a third-party state on behalf of an ally—is highly uncertain. The clarity of the logic obscures the gravity of the act: the use of a uniquely[3] destructive weapon that potentially entails the death of millions and uncontrolled escalation presenting existential risk to humanity (if additional nuclear powers were to be drawn in). Ordering a nuclear attack on any state—even one directly at war with the US—is an enormous psychological burden for any US president; to do so primarily for the benefit of an ally, rather than primarily for the US and its population, requires an almost unimaginable level of fortitude. The credibility of extended nuclear deterrence rests, however, precisely on the assumption that this presidential fortitude is reliable, that the US president would trade San Francisco for Busan.[4] This unimaginable, yet reliable fortitude is necessary, and a heavy lift, even in the most favorable of circumstances, which, one hastens to add, do not obtain with the current situation of US extended nuclear deterrence for South Korea. Credible, reliable extended nuclear deterrence requires—in order to buttress the requisite presidential fortitude—a rock-solid relationship between allies (including between ally leaders), as well as the patron state’s principled purpose and clarity about the strategic value of meeting its extended nuclear deterrence obligations. There is reason to doubt this in the current situation under US president Donald Trump.

To begin with, Trump is notorious for his unreliability as a partner, an ingrained aspect of his psychological profile that extends back to his period as a businessman and has remained prominent during his White House mandate. Beyond his general propensity for personal betrayal, Trump has repeatedly denigrated US allies, including South Korea. Why should South Korea—and, perhaps more importantly from an extended deterrence perspective, North Korea or another nuclear-weapon-possessing adversary of South Korea—believe a generally mendacious and unreliable Trump would honor the US obligation of a retaliatory nuclear strike on behalf of South Korea when doing so potentially would put the US in danger, clearly violating Trump’s “America First” foreign policy orientation?

Beyond the sheer problem of the unreliability and alliance hostility of Trump—who might, after all, soon be out of office and succeeded by Joe Biden, a seasoned supporter of US alliances—what he represents about the US body politic is also discouraging for US extended nuclear deterrence for South Korea. Trump’s administration—which, despite being riven with corruption, grift and graft, lawless opportunism, incompetence, and negligence, enjoys the support of 35%-45% of the population, who ipso facto finds this behavior benign—is an expression of how little the US government and broader population are dedicated to upholding the rule of law. This problem is unlikely to vanish even with Trump out of office—it is, rather, a flaw in the national character of the US at the moment. This raises the question—critical for South Korea—of how seriously a state that does not sufficiently respect domestic rule of law can be expected to respect its defense commitment to a treaty ally.

Additionally, one must recall that Trump’s foreign policy—including alliance hostility that casts doubt on extended nuclear deterrence for South Korea—is also an expression of the aggregate preference of the US population to be less militarily engaged abroad. The historical default foreign policy preference of the broad US population is moderate isolationism, with the more interventionist, proactive, alliance-focused post-WWII period an exception. It is worth asking if the US can be trusted to support a policy as laden as extended nuclear deterrence for South Korea—with the major risks that entails—given that the US population clearly supports removal of trivial numbers of US troops even from places such as Afghanistan, Syria, and Iraq, which have extremely limited capacity to inflict damage on the US territory.

Turning from domestic political factors in the US to the international strategic context for US extended nuclear deterrence for South Korea, the situation is also unfavorable. Any realistic adversary scenario involves a third-party state (North Korea, China, Russia) that could strike US territory with a residual (third) strike, if the US were itself to retaliate (second strike) on behalf of South Korea in reprisal for the third-party state’s initial (first) strike against South Korea. The US and South Korea may game out the scenarios to locate a point of US dominance on the escalation ladder (indeed this is one of the reasons for the US introduction of low-yield warheads for SLBMs in the western Pacific), but the bottom line is that the third-party states most likely to be involved in conflict with South Korea are sufficiently nuclear-armed that, under conflict conditions, a strike on US territory cannot be excluded. Consequently, there is a chance that the US president would avoid that risk by not launching a nuclear attack against said third-party state in accordance with US extended nuclear deterrence commitment.

South Korea must know this. North Korea certainly does. Indeed Pyongyang just provided a vivid picture of its own deterrence capabilities in its latest October 10 military parade, which displayed a new, larger ICBM and a new variant of the Pukguksong series SLBM. The ICBM (provisionally known as the Hwasong-16), which can strike anywhere in the continental US, is presumably capable of carrying multiple warheads and decoys or a larger thermonuclear warhead with better and more robust penetration aids and other countermeasures. These technologies seem designed to defeat US ballistic missile defense, which is a problem for extended nuclear deterrence because a sufficiently reliable and comprehensive missile defense sys-tem would buttress the US perception that it could strike North Korea without fear of reprisal. That is, to the extent that North Korean capabilities cast doubt on the effectiveness of US ballistic missile defense, they erode the credibility of extended nuclear deterrence for South Korea.[5] Less is known about the new Pukguksong SLBM, but its deployment would also complicate US calculations of its deterrence capabilities vis-à-vis North Korea.

Neither of these new sys-tems has been tested, and are ostensibly not ready for operational deployment. And in the case of North Korean SLBMs, there are enormous unanswered questions about command-and-control, the survivability of North Korea’s noisy and outdated submarines, and other aspects of reliability. Nonetheless, the ongoing quantitative and qualitative development and improvement of Pyongyang’s nuclear arsenal represent a technological wedge for decoupling Washington from Seoul. From a strategic perspective, the incentive structure to provide extended nuclear deterrence for the purpose of order building/maintenance and nonproliferation changes when the third-party state has nuclear weapons that can strike the extended nuclear deterrence provider.[6]

Effects and Responses

The bottom line is that in the current environment, South Korea cannot truly trust US extended nuclear deterrence. Yet it is also, seemingly, consigned to do so, absent a fraught attempt at developing an independent nuclear deterrent that would likely break the US-ROK military alliance and have grave effects on both the South Korean economy (which might face economic sanctions for proliferation activities) and regional stability in Northeast Asia. So, how might South Korea mitigate the downsides of this unenviable situation?

Three potentially mutually reinforcing paths come to mind. The first task is strengthening South Korea’s conventional deterrence capabilities. North Korea’s nuclear weapons do, of course, represent a risk to South Korean security, whether through inadvertent or intentional use, but both of these scenarios are exceedingly unlikely, and it is in fact North Korean conventional capabilities (with, to be sure, Pyongyang’s nuclear sword of Damocles hanging in the background) that are the greater and more direct threat to South Korea. If Seoul successfully invests in conventional deterrence capabilities,[7] it can likely raise the cost of North Korean conventional aggression sufficiently that North Korean leadership will not have a competitive strategy for enacting it. South Korea is already taking some of these steps, both through its rising defense budget—including for R&D and procurement—and the conceptual triad of Kill Chain, Korean Air and Missile Defense, and Korea Massive Punishment and Retaliation. One notes also that Seoul should expect Pyongyang to continue to engage in “grey zone” actions that undermine South Korean security and resolve slowly over time, while no single action rises to a level sufficient to warrant a major South Korean kinetic response. It would behoove Seoul to develop better strategies, and the requisite capabilities for applying them, to deter, and if necessary, counter, these “grey zone” actions.

A second step is considering initiating a Korean Peninsula Nuclear Planning mechanism in which South Korea would have a role. With some adjustment for different contexts, this would be analogous to the Nuclear Planning Group au sein de l'OTAN. Cela renforcerait la confiance concernant les questions de politique nucléaire — stratégie, options d'utilisation nucléaire/ciblage, etc. — des deux côtés de l'alliance États-Unis-Corée du Sud. De manière cruciale, cela intégrerait formellement Séoul dans le processus d'examen et d'adaptation de la politique de dissuasion nucléaire étendue en fonction de l'évolution des menaces. Cette approche — qui a déjà été proposée, et qui présente certains inconvénients, notamment la courbe d'apprentissage apparemment abrupte de Séoul dans ce domaine en raison de son manque d'expérience — constitue une étape intermédiaire entre l'inaction et le redéploiement[8] d'armes nucléaires américaines sur le territoire sud-coréen, ce qui serait clairement très provocateur vis-à-vis de la Corée du Nord et de Pékin, et pour lequel il n'y a pas suffisamment de soutien populaire en Corée du Sud. Les États-Unis ne sont, en règle générale, disposés à envisager ce type de coopération de défense de haut niveau qu'avec leurs alliés les plus proches, groupe auquel la Corée du Sud appartient toujours. Malgré quelques turbulences récentes dans l'alliance — dont beaucoup découlent des idiosyncrasies du président Trump — il existe une histoire de coopération institutionnelle entre les ministères des affaires étrangères et de la défense des États-Unis et de la Corée du Sud, ainsi que des niveaux élevés de soutien populaire à l'alliance parmi la population plus large des deux pays. Ces piliers de coopération pourraient être utilisés pour soutenir la création d'un mécanisme de planification nucléaire pour la péninsule coréenne.

Enfin, Séoul devrait prendre des mesures — après l'élection présidentielle américaine — pour améliorer la détérioration de ses relations avec Washington. Cela sera probablement plus facile avec une administration Biden, compte tenu de ses déclarations selon lesquelles une priorité majeure de sa politique étrangère serait de réparer les alliances américaines. Cependant, c'est essentiel quelle que soit l'issue de l'élection. En fin de compte, la dissuasion nucléaire étendue n'est crédible que dans la mesure de la solidité de l'alliance dans laquelle elle est intégrée. À cette fin, Séoul devrait examiner dans quelle mesure cette solidité pourrait être renforcée en s'intéressant davantage aux préoccupations de sécurité américaines dans la région plus large de l'Asie de l'Est. C'est difficile pour les gouvernements sud-coréens qui sont naturellement préoccupés par la péninsule coréenne et craignent d'offenser Pékin, mais il serait salutaire pour l'alliance États-Unis-Corée du Sud, et donc pour la dissuasion nucléaire étendue, que Séoul indique qu'elle a également un intérêt dans les politiques régionales de Washington. Une bonne action en mérite une autre. ■

[1] Le paradoxe « stabilité/instabilité » nonobstant. Voir : Glenn Snyder, Deterrence and Defense (Princeton, NJ : Princeton Univ. Press, 1961), p. 226.

[2] Les agressions de bas niveau et asymétriques sont abordées ci-dessous.

[3] En effet, il existe toute une littérature discutant de la manière dont le caractère sui generis des armes nucléaires a produit une forte interdiction normative — le « tabou nucléaire » — sur la première utilisation des armes nucléaires.

[4] Pendant la Guerre Froide, la France a poursuivi une dissuasion nucléaire indépendante en dehors du contexte de l'OTAN précisément parce que Charles de Gaulle ne croyait pas que les États-Unis « échangeraient New York contre Paris ».

[5] C'est également vrai pour le Japon.

[6] Encore une fois, c'est également vrai pour le Japon.

[7] Y compris, mais sans s'y limiter, les avions de chasse, les missiles et la défense antimissile/antiaérienne, la technologie de guerre anti-sous-marine, le renseignement/la surveillance/la reconnaissance, les systèmes de combat terrestre améliorés, les systèmes autonomes et la robotique pour atténuer les futures pénuries de main-d'œuvre dues à la démographie, les capacités cybernétiques, etc.

[8] Il y a eu quelques débats récemment sur la possibilité de réintroduire des armes nucléaires tactiques américaines sur le territoire sud-coréen.

• Mason Richey est professeur associé de politique internationale à l'Université des études étrangères de Hankuk (Séoul, Corée du Sud) et contributeur principal à l'Asia Society (Corée). Le Dr Richey a également occupé les postes de chercheur invité POSCO au East-West Center (Honolulu, HI) et de boursier DAAD à l'Université de Potsdam. Ses recherches portent sur la politique étrangère et de sécurité des États-Unis et de l'Europe appliquée à la région Asie-Pacifique. Des articles universitaires récents ont été publiés (entre autres) dans Pacific Review, Asian Security, Global Governance, et Foreign Policy Analysis. Des analyses plus courtes et des articles d'opinion ont été publiés dans 38North, War on the Rocks, Le Monde, le Sueddeutsche Zeitung, et Forbes, entre autres. Il est co-éditeur du volume The Future of the Korean Peninsula: Korea 2032 (Routledge, à paraître en 2021).

• Gestion et édition : Jin-kyung Baek, chercheuse à l'EAI
              Contact : 02 2277 1683 (poste 209) | j.baek@eai.or.kr