In an elaborate ceremony in August this year, North Korea celebrated the delivery of 250 nuclear-capable missile launchers to frontline military units. To a crowd of spectators, leader Kim Jong Un declared that North Korea needs to bolster its nuclear deterrence capabilities and that the launchers were an “up-to-date tactical attack weapon” that he “personally designed.”

A month later, President Yoon Suk-yeol promised that South Korea’s conventional weapons, coupled with U.S. extended deterrence, would deter North Korea. South Korea has for almost a decade pursued a conventional counterforce strategy, where it seeks the capability to target North Korea’s nuclear weapons preemptively. In addition, it threatens North Korean leaders with massive punishment. However, despite introducing new weapons, such as the Hyunmoo-5 ballistic missile, South Korea’s deterrence strategy is in dire straits.

As North Korea’s deployment of the new missile launchers attests, South Korea has found itself in an asymmetric arms race that is impossible to win. No matter what conventional capability South Korea introduces, North Korean nuclear weapons will always have the upper hand. This fundamental asymmetry could severely impact crisis stability on the Korean Peninsula. This dynamic, and Pyongyang’s predictable reaction to Seoul’s strategy, provides a sobering lesson for other actors interested in conventional counterforce capabilities, such as Japan.

South Korea’s strategic options are all bad. While conventional counterforce is proving counterproductive, the pursuit of nuclear weapons is a path ridden with danger. Moreover, while South Korea may attempt to ease tensions with the North, working for disarmament is likely a fool’s errand. Extended deterrence is therefore the least bad alternative for South Korea. However, confidence in the alliance is eroding, and no matter who is elected in November, the United States will need to craft its alliance management policies carefully, reassuring South Korea while avoiding accelerating what is already a worsening arms dynamic.

Good Money After Bad?

The South Korean government continues to invest significant proportions of its defense budget in its counterforce and countervalue capabilities. When combined, these capabilities, also known as the three-axis system, include command and control systems, sensors, and weapons such as ballistic and cruise missiles that are aimed at nullifying North Korea’s nuclear capabilities while also punishing its leadership. There is also a missile defense component aimed at intercepting incoming North Korean missiles. All of these capabilities soon will be placed under the newly formed Strategic Command, which is charged with not only controlling a large number of systems across the services but also implementing greater integration of the South Korean conventional systems with U.S. nuclear capabilities.

The problems with this approach are numerous. First, conventional counterforce is extremely difficult to enact, even against a weak nuclear adversary. In the early stages of North Korea’s nuclear weapons program, when it possessed a small number of liquid-fueled missiles that were slow to prepare for launch, South Korea may have had a chance at a degree of success in a counterforce strike. In recent years, however, North Korea’s nuclear weapons capabilities have improved dramatically, and its arsenal of particularly short-range missiles has expanded rapidly. As a result, conventional counterforce on the Korean Peninsula has become almost impossible to operationalize. To preempt a North Korean nuclear attack, South Korea would have to strike possibly hundreds, if not thousands, of targets within a severely constrained time frame. Arguably, North Korea only needs to have one nuclear warhead get through South Korea’s defenses for such an attack to succeed.

Further, there is evidence that the conventional deterrence strategy negatively affects strategic stability. The arms race pressures it creates are obvious and in evidence. Unfortunately for leaders in Seoul, it is much easier for North Korea to expand its nuclear weapons program than it is for South Korea to maintain conventional capabilities that can credibly counter it. In addition, in a crisis, North Korean leaders would potentially have incentives to use nuclear weapons early, facing a “use them or lose them” dilemma. The signals in its 2022 nuclear law that “a nuclear strike shall be launched automatically and immediately” if nuclear command and control “is placed in danger owing to an attack by hostile forces” are an entirely predictable response to South Korea’s threats against North Korean leaders.

To be sure, the three-axis system has given South Korea a conventional warfighting capability that virtually all modern militaries would covet. It now possesses substantial magazine depth and a range of weapons linked to advanced command and control systems that enable strategic-, operational-, and tactical-level strikes against North Korea. Hence, from a conventional perspective, what South Korea has built has significant deterrent potential.

Further, in any peninsular scenario involving the use of nuclear weapons, it is highly unlikely that conventional and nuclear use will be ring-fenced. South Korea’s strike and missile defense capabilities will play a substantial role in fighting North Korea. Hence, proponents of the strategy can also legitimately argue that it may both produce uncertainty among North Korean leaders and contribute to damage limitation, thereby changing the risk calculus in Pyongyang. The strategy does not, however, provide deterrence stability on the peninsula.

Other Bad Options: Nuclear Pursuit, or Hoping for Disarmament

The challenges facing the conventional counterforce strategy seem to be tacitly, if not openly, acknowledged in Seoul. Among the South Korean elite, many are now in favor of bolstering nuclear latency, or strengthening their country’s capability to acquire nuclear weapons rapidly but without building them. South Korea has an advanced nuclear industry and sophisticated delivery vehicles but lacks the enrichment and reprocessing capabilities necessary for producing fissile material for nuclear weapons. A challenge of this approach, as Lami Kim has recently highlighted, is that openly calling for stronger nuclear latency undermines the chances that Washington will approve it. Moreover, while useful as an insurance policy, hedging does not solve immediate deterrence challenges, as building nuclear weapons would take time, even if South Korea did possess enrichment and reprocessing technology.

Calls for a full breakout, and indigenously developing nuclear weapons, have also grown stronger. Among the public, support for nuclear armament has consistently averaged over 70 percent for years. However, nuclear breakout remains fraught with danger and is therefore an unattractive option, something that South Korean elites currently seem to acknowledge. South Korea would risk international opprobrium, sanctions from key trading partners (including the United States and China), and a breakdown in the alliance. Moreover, in the period between a breakout decision and acquisition, it would potentially be vulnerable to a preventive strike from North Korea.

Another approach would be the revival of diplomatic initiatives that were supported by the previous South Korean administration. To be sure, easing tension between the two Koreas could be worthwhile and may lessen the likelihood of armed conflict. However, North Korea’s stance has hardened significantly in recent years. In January 2024, Kim stated that the division between North and South Korea was permanent and that South Korea was the primary foe. Military agreements aimed at mitigating potential flashpoints have also been annulled. Over the short term, it is highly unlikely that North Korea will be receptive to diplomatic overtures emerging from South Korea or Washington. Even the Moon administration, which spoke much more softly regarding North Korea, still sought to carry a big stick, something that North Korea, of course, noticed.

Hopes for disarmament appear equally if not more unrealistic. North Korea has signaled clearly that it is a nuclear state. The longer South Korea, the United States, and the rest of the world formally refuse to accept this reality and insist on disarmament, gradual or otherwise, as a condition of improved relations, the longer this impasse will persist.

Back to Leaning on the United States

That South Korea is now seeking closer strategic integrations with the United States, including leaning on extended deterrence in political and signalling rhetoric, reflects the shortcomings of its other strategic options. In continuously designing around South Korean capabilities, North Korea has forced Seoul to reduce its emphasis on creating a counterforce capability that can function with reduced or no U.S. assistance.

The nuclear consultative group, announced in the Washington Declaration, provides a framework that includes planning, exercises, and consultations for what is now termed “conventional and nuclear integration” between the United States and South Korea. Of course, South Korea’s conventional counterforce capabilities can contribute to extended deterrence. However, it is unclear how this will change the deterrence calculus in Pyongyang. The new relatively new strategic concepts of conventional counterforce and conventional-nuclear integration will not mitigate the possibility of all actors being trapped in a deterrent loop. In essence, reassurance linked to the perceived need for “increased deterrence” through the provision or introduction of more capabilities risks continuously raising the strategic stakes on the peninsula.

The United States, massively superior to North Korea in terms of nuclear weapons, continues to avoid committing to the use of nuclear weapons in response to a North Korean nuclear attack. Fundamentally, therefore, with one exception, nothing has changed in terms of North Korean-U.S. nuclear relations. The one exception is North Korea’s capability to strike the U.S. homeland with a nuclear weapon.

The continued mixed messages from the Yoon administration regarding South Korea’s nuclear desires suggest that the Nuclear Consultative Group has not fully assuaged doubts in Seoul. Neither have high-profile military activities such as the visit of a U.S. nuclear ballistic missile submarine to Busan in July 2023. This leads to the possibility that with every North Korean advance in its missile and nuclear capabilities, the United States will be faced with increased calls for nuclear reassurance measures from South Korea. These measures could include permitting South Korea to build nuclear latency, committing to a nuclear response should North Korea use nuclear weapons, the deployment of strategic assets on the Korean Peninsula, or the stationing of U.S. nuclear weapons on South Korean soil.

Although the current U.S. administration has been reluctant to go down any of these paths, calls for policy shifts will likely only increase in the future. The next U.S. president will be confronted with the challenge of alliance management in the face of an intractable adversary.

Managing the Alliance

Barring a major strategic shift, the next administration will also have to consider the degree to which it seeks to support South Korea’s conventional counterforce strategy. In essence, Washington has two broad options.

The first is for Washington to maintain the status quo. Given the inexorable development of North Korean nuclear weapon capabilities, this is likely to continue the current degree of policy inertia where South Korea is incrementally provided with or allowed to develop ever greater strategic capabilities. Such continued investments will do little to bolster deterrence stability on the peninsula.

The second option is to pay less attention to South Korean requests for greater capabilities while continuing to provide extended deterrence. Given Seoul’s reliance on the United States for multiple capabilities, this policy path may have benefits, such as dampening the arms race pressures on the peninsula. However, it also produces longer-term risks. If the United States is perceived as ignoring South Korea’s legitimate security concerns, it risks damaging a relationship that is crucial in the U.S. competition with China.

To be sure, the differences between these two options is one of degree. Most likely, the future U.S. administration will try to thread the needle and support some of South Korea’s capability acquisition, while holding back in other instances. However, U.S. policymakers should be aware that relentless South Korean pursuit of conventional counterforce has risks. A fruitless policy of capability one-upmanship with North Korea should be avoided. A nuclear North Korea cannot be wished away, and policymakers in both Washington and Seoul should prioritize maintaining strategic stability.

Conventional Counterforce?

The challenges arising from South Korea’s conventional counterforce strategy provide lessons for other actors, including Japan. Although Japan’s pursuit of what it refers to as “counterstrike” capabilities is not yet as far advanced as South Korea’s, it is acquiring several new long-range strike options, including Tomahawks and a domestically produced cruise missile. Although the “counterstrike” capabilities are designated for standoff strikes against an enemy invading Japan or its territorial waters, several of the weapons Japan is acquiring can also be used preemptively for counterforce strikes against North Korea (or even parts of China). Analysts have called for South Korea and Japan to coordinate and in effect create a joint preemptive counterforce strategy.

Similar to the South Koren case, Japan’s acquisition of long-range strike capabilities makes eminent sense from a deterrence and warfighting perspective in a conventional context. It is understandable that Japan is abandoning its past restrictions on long-range strike options. However, regardless of Japanese intentions, its acquisition of long-range strike capabilities when linked to nuclear threats could create some of the same risks to strategic stability as those created by South Korea’s programs. It will impact the postures of Japan’s adversaries and may create new escalation risks. Indeed, Chinese strategists are also concerned about the conventional precision-strike capabilities of both the United States and its allies. Most importantly, in this context, Japanese possession of conventional precision-strike capabilities is unlikely to deter North Korea or China from using nuclear weapons if leaders in those states see no other option.

Unfortunately, the missile and nuclear buildups in Asia will be extremely difficult to stall. However, explicitly linking conventional precision capabilities to nuclear deterrence increasingly seems to be a losing proposition — and a recipe for worsening arms race pressures in the region.

Ian Bowers is a senior researcher at the Norwegian Institute for Defence Studies and an adjunct researcher for the Oslo Nuclear Project.

​Henrik Stålhane Hiim is an associate professor at the Norwegian Institute for Defence Studies. He works on nuclear strategy, arms control, and security in East Asia.

Image: Baek, Jong-sik via Wikimedia Commons