Korean National Security Policy at the Crossroads

Professor Christoph Bluth │University of Bradford

The changing security environment in East Asia and the challenge facing South Korea

In the 21st century, South Korea is facing a complex security environment as one of the few liberal democratic states persistently threatened by a neighbor and, therefore, is a frontline state in the struggle for the emerging configuration of regional geopolitics. The persistent rivalry between the Democratic People’s Republic of Korea (North Korea) and the Republic of Korea (South Korea) is, in part, a consequence of post-Second World War ideological divisions that developed into the Cold War. A dividing line between North and South Korea (since 1953: the demilitarized zone) also has been a border between East and West. As a consequence, the scope for developing any kind of inter-Korean relationship was limited. At the same time, the embedding of the two Koreas on the different sides in the Cold War was also a stabilizing factor as both Koreas enjoyed external security guarantees, and the United States had nuclear weapons deployed on the Korean peninsula to reinforce extended deterrence.

The risk of armed conflict between states in the contemporary international system is low except in some specific crisis regions such as South Asia or the Korean peninsula.(1) During the Cold War, nuclear weapons were central to the struggle between the Soviet Union/Warsaw Pact and the United States/NATO. These weapons were the dominant factor in the military balance that involved substantial strategic nuclear arsenals with a triad of long-range delivery systems, preparations for large-scale conventional conflict in Europe supported by tactical nuclear forces, and proxy conflicts in other regions. Although the United States and Russia still maintain substantial strategic nuclear forces, their role has changed fundamentally. As the prospect of large-scale warfare in Europe retreated, the United States developed effective global power projection capabilities based on conventional weapons while Russia’s conventional military capabilities declined to the point that Moscow considered nuclear weapons as essential for a deterrent of last resort, as well as Russia’s only claim to be a Great Power.

However, since Russia launched its war of aggression against Ukraine, the role of nuclear weapons in the increasing tension between the Great Powers needs to be re-examined. The Ukraine War has also resulted in the development of a strategic axis between North Korea and Russia, as North Korea is assisting Russia in replenishing stocks of artillery munitions and ballistic missiles. This may involve cooperation on missile development that will enable North Korea to develop and deploy advanced intercontinental ballistic missiles.(2)

The first decade after the Cold War seemed to confirm the view that the nuclear powers would not face military contingencies where nuclear weapons would be required as a deterrent or as a useful military tool. Indeed, for the first time in their history, the countries of Western and Central Europe did not face an external enemy. For example, when conflict broke out in the Balkans four nuclear powers were engaged with their armed forces, but their nuclear weapons had no relevance for their conduct or the course of the conflict. As very few states faced an external threat that would compel them to acquire nuclear weapons, almost all non-nuclear states joined the Nuclear Nonproliferation Treaty (NPT). The tensions on the Korean peninsula and the emerging nuclear threat appeared to be an outlier in the overall global security landscape.

The changing strategic environment on the Korean peninsula

The strategic environment is changing in a way that reduces the credibility of extended deterrence. North Korea began 2023 as it had ended 2022 – with the same saber-rattling in the form of missile flight tests. Having launched more missiles in 2022 than in any other year, on the morning of January 1, 2024, North Korea tested a large new multiple-launch rocket system that, according to Supreme Leader Kim Jong-un, can strike any part of South Korea with tactical nuclear warheads.(3)

On the same day, Kim called for the North to “exponentially increase” its stock of nuclear weapons. There has been frequent reshuffling at the top of the military as part of an effort to push the military harder to achieve greater readiness and combat capability. However, Pyongyang’s recent displays of belligerence have drawn swift reactions from Seoul. After five drones penetrated South Korean airspace (one violating the no-fly zone over the presidential office in Seoul), South Korean President Yoon Suk-yeol reprimanded the South Korean military for not shooting them down and ordered a review of the 2018 Comprehensive Military Agreement with North Korea. The agreement established air, land, and sea buffer zones to reduce the risks of armed conflict. North Korea’s repeated violations of the agreement led to speculation that Seoul could cancel the deal, which it finally did in June 2024. Analysts in both Seoul and Washington, meanwhile, have been watching developments in Pyongyang carefully, after North Korea revised its nuclear law in September 2023. The law declares that North Korea’s nuclear doctrine now mandates an “automatic and immediate nuclear response,” which has put Korea’s security on a knife-edge.

Some analysts believe that Pyongyang’s new nuclear posture is a response to Yoon’s statement that South Korea should consider preemptive strikes against the North’s command-and-control systems. Most analysts believe South Korea probably can strike North Korea’s leadership using precision guidance missiles and high-level reconnaissance capabilities in the case of a crisis. While this is said to be a retaliatory “kill chain”, these systems could also be used preemptively, a strategy that Yoon championed during his 2022 election campaign. This was subsequently underlined when he took U.S. President Joe Biden on a visit to the “kill chain command center.”

On the Korean peninsula, the geographic distances are relatively short – the capital, Seoul, for example, is only 23km south of the Military Demarcation Line and North Korea. Early warning against a surprise missile attack is practically non-existent, raising the risk of pre-emptive strikes.

Yoon has declared North Korean denuclearization to be the minimum requirement for the South to engage with the North on security and economics.

On August 15, 2023 – Korea’s Liberation Day – Yoon made an offer with incentives for the North to denuclearize in return for what he called “an audacious plan that will vastly strengthen North Korea’s economy and improve the quality of life for its people.”

Seoul’s principal concern is that North Korea has recently become “more hostile and aggressive with its provocations based on its confidence over its nuclear and missile capabilities.” The Yoon government once again has designated North Korea as “the enemy” in the National Defense White Paper.

The reliability of the US-ROK alliance and South Korea’s nuclear dilemma

During the Trump administration, disputes over the cost of U.S. forces based in South Korea and the Theater High-Altitude Air Defense (THAAD) missile defense system created severe tensions in the bilateral alliance, leading to doubts about the reliability of Washington’s extended nuclear deterrence. Biden has restored some level of confidence – but he is a well-known advocate of nuclear arms control and “no first use” of nuclear weapons and has refused to advocate nuclear use against conventional threats.

As the Trump administration cast doubt over the credibility of the U.S.-ROK alliance, conservatives in South Korea increasingly have voiced the need for South Korea to develop its own nuclear arsenal to counter North Korea. Pyongyang’s missile testing, as well as Kim’s recent statements, have revived these voices. But the Yoon administration knows that any movement toward an independent nuclear deterrent would put its relations with Washington at risk and could even result in U.S. sanctions.

Alternatively, U.S. nuclear weapons could be redeployed on South Korean territory. They were withdrawn by the George H.W. Bush administration in 1991 at the end of the Cold War. Yoon raised this as a possibility during his presidential campaign, but the Biden administration does not support such a move, which would seriously antagonize China and go against Biden’s political instincts.

The fundamental problem with the approach of the current South Korean government is that it has no chance of success in reducing inter-Korean tensions. Over the past three decades, all efforts to persuade North Korea to forego nuclear weapons have failed – so engagement that is conditional on complete denuclearization is a non-starter.(4)

However, it is conceivable that the South and the North could strike some kind of deal to limit the North’s development of nuclear weapons and scale back its testing and military provocations in return for political engagement and the lifting of some sanctions. South Korea and the U.S. could consider this to limit the potential for serious escalation.

China and regional security

China’s greater assertiveness is one of the key factors of the changing strategic landscape. The Biden administration believes that it is confronting a more belligerent China, which now seems to have decided to expand its long-range strategic nuclear arsenal. This and the threat to Taiwan along with the South China Sea issue means that the risk of armed conflict in East Asia is increasing, while the willingness or even the ability of the U.S. to engage in such a conflict is now coming more into question.(5)

The United States is confronting the reality that the Chinese military is in the process of modernization, including force projection capabilities based on a large navy and air force. This means that the United States will have to both enhance its forces in the region, as well as rely more on its allies, including Australia and the United Kingdom. However, this poses a potential new challenge for regional allies, namely Japan and South Korea. Although this is not yet being discussed publicly, it involves the potential participation of Japan and South Korea in conventional force projections beyond their national self-defense.

South Korea’s nuclear dilemma

Relying on extended nuclear deterrence from an ally creates two potentially distinct and opposite problems for South Korea. The first is that adversaries might not consider the nuclear guarantee to be credible and, therefore, it could be ineffective. The second is that non-nuclear allies such as South Korea may have no veto of the threat or the actual use of nuclear weapons and, therefore, become embroiled in a conflict initiated by the guarantor.(6) South Korea faces both of these problems, although only the first one is subject to public discussion. To render extended nuclear deterrence more effective, forward deployment of nuclear weapons either in the region or on South Korean territory could address the credibility issue because these weapons systems would directly target the adversary while also being distinctly visible. If they were deployed on South Korean territory, the binding effect would be quite strong because, in the case of a North Korean attack, the U.S. could not risk the weapons being lost. On the other hand, this would raise other geopolitical issues because of China. Beijing without a doubt would see such weapons as a threat, and indeed the United States might see the deployment as having a dual deterrence purpose concerning North Korea and China over Taiwan. The Chinese reaction could be expected to be quite severe.(7)

As a result of the increasing challenge to extended deterrence, Yoon wanted Biden to highlight the U.S. commitment to nuclear deterrence. At the summit in April 2023, nuclear consultation arrangements that were agreed upon (the Washington Declaration), which included the establishment of a Nuclear Consultative Group, that could be a useful mechanism of reassurance for South Korea, especially if South Korea were to become a party to nuclear contingency plans for a Korean conflict.(8) At the August 2023 Trilateral Summit in Camp David involving cabinet-level members from the United States, Japan, and South Korea, the countries “affirmed their enduring commitment to strengthen trilateral security cooperation to deter nuclear and missile threats posed by the Democratic People's Republic of Korea (DPRK) and to achieve the complete denuclearization of the DPRK in accordance with relevant United Nations Security Council resolutions (UNSCRs).”(9)

However, the South Korean government might fear that they might not be sufficient to enhance deterrence with respect to North Korea, while the U.S. may not be willing to share such secrets or commit to specific contingencies.(10) This comes at the time when North Korea has formally abandoned the goal of Korean unification, withdrew from all forms of engagement and interaction with the South, and declared that it is preparing for war. This does not mean that armed conflict beyond small-scale skirmishes is likely. However, consistent with current global realignments, Northeast Asia’s security environment is deteriorating, which is creating profound challenges for the United States and its allies in the region.

1 Robert A. Wampler, Trilateralism and Beyond: Great Power Politics and the Korean Security Dilemma During and After the Cold War (New Studies in U.S. Foreign Relations, Kent State University Press, Kent, 2011.

2 Kelsey Davenport, “U.S. Says North Korea Shipped Arms to Russia”, Arms Control Today, November 2023.

3 Christoph Bluth, “North Korea: record number of missile tests in 2022 has raised fears of nuclear confrontation with the South,” The Conversation, 10 January 2023, https://theconversation.com/north-korea-record-number-of-missile-tests-in-2022-has-raised-fears-of-nuclear-confrontation-with-the-south-197174.

4 Sung-wook Nam, North Korean Nuclear Weapon and Reunification of the Korean Peninsula, World Scientific, London, 2019.

5 Nigel Inkster, “Strained US–China Relations and the Growing Threat to Taiwan,” Chapter 2 in Asia-Pacific Regional Security Assessment 2023, The International Institute for Strategic Studies, London, https://www.iiss.org/publications/strategic-dossiers/asia-pacific-regional-security-assessment-2023/aprsa-chapter-2/.

6 Brian Radzinsky, “Nuclear Risks in Northeast Asia: Opportunities and Challenges for Extended Deterrence and Assurance,” Journal for Peace and Nuclear Disarmament, Vol.1, Issue 2, 363-382, 2018, https://doi.org/10.1080/25751654.2018.1482527.

7 Kim Tong-Hyung, China, South Korea clash over THAAD anti-missile system, Defense News, 10 August 2022, https://www.defensenews.com/global/asia-pacific/2022/08/10/china-south-korea-clash-over-thaad-anti-missile-system/.

8 “Washington Declaration,” The White House, 26 April 2023, https://www.whitehouse.gov/briefing-room/statements-releases/2023/04/26/washington-declaration-2/.

9 “Camp David Principles,” The White House, 18 August 2023, https://www.whitehouse.gov/briefing-room/statements-releases/2023/08/18/camp-david-principles/#:~:text=As%20we%20move%20forward%2C%20we,shared%20norms%2C%20and%20common%20values.

10 Christoph Bluth, “US-Korea summit: Joe Biden’s ‘American Pie’ won’t include stationing nuclear weapons on the peninsula,” The Conversation, 28 April 2023, https://theconversation.com/us-korea-summit-joe-bidens-american-pie-wont-include-stationing-nuclear-weapons-on-the-peninsula-204628.