South Korea Needs a New Nuclear Strategy

South Korea Needs a New Nuclear Strategy

South Korea needs to formulate a nuclear diplomatic strategy that emphasizes the incentives its nuclear arsenal could offer to the alliance.


Considering South Korea’s neighbors’ ever-changing nuclear postures, Seoul’s strategic inflexibility and insistence on its existing policy are highly concerning. The uncontrolled nuclear arms race is worsening so rapidly that South Korea is approaching a scenario where it can no longer take direct assistance from third countries or unconditional nuclear retaliation for granted.

Fortunately, Washington’s interests in the Asia-Pacific favor Seoul playing a more significant role. Now that the Republic of Korea’s (ROK) commitment to trilateral cooperation with the United States and Japan is stronger than ever, Seoul must be prepared to become a more responsible ally. Amid regional instability, it needs calibrated nuclear diplomacy that reflects the different values it must pursue with each player.


Uncertainty, Volatility, and Anxiety

The current nuclear diplomacy fails to address uncertainty. Officials promote the Washington Declaration as if it’s new, but it is a rhetorical repetition of extended deterrence. The “overwhelming and powerful response” to put an end to Kim Jong-un’s regime would require using strategic nuclear weapons in response to North Korea’s use of tactical nukes. This is unrealistic because it would potentially involve the United States in a multisided nuclear war. A conventional first strike against a nuclear-armed state is even more dangerous.

There are commonly shared concerns about over-escalating regional tensions. In the past, South Korea has experienced precedents that show how the United States would possibly respond to a crisis. When a South Korean frigate was sunk and a northwestern island shelled in 2010, the United States rebuffed Seoul’s intention to counterattack out of fear of escalating tensions.

Anxiety arises from the fact that no one can ascertain if a nuclear state would proportionally provide immediate nuclear retaliation without considering political backlash. Ukraine abandoned its inherited nuclear weapons in exchange for security guarantees in 1994 but ended up waging a war with Russia. President Emmanuel Macron stated that France would not respond with nuclear weapons if Moscow nukes Ukraine. NATO also implied that it would not use nuclear arms on behalf of Kyiv. These cases expose conventionally armed states’ vulnerability.

North Korea: Justification and Benefits

The Joint Declaration on the Denuclearization of the Korean Peninsula has already been unilaterally obliterated by Pyongyang’s six nuclear tests and now expanding nuclear capabilities. Kim has officially declared that Pyongyang will never give up its nuclear arsenal; the North Korean leader is now focusing on acquiring nuclear-powered submarines and will have more than 200 nuclear warheads by 2030.

Nevertheless, South Korea did not nullify the joint declaration based on reciprocity, rather respecting it alone. It has essentially become a pledge of South Korean denuclearization. Seoul can thus legitimately suspend its adherence to the declaration before it is too late to counteract.

United Nations sanctions have had little impact on North Korean nuclearization. It has been largely limited as Beijing and Moscow exercised veto rights that facilitated North Korea to go nuclear faster. Going forward, U.S.-led sanctions on Kim will continue to be blocked by them, ultimately perpetuating the vicious cycle of a nuclear standoff.

As such, it is a foregone conclusion that North Korea will proceed with its seventh nuclear test, despite international opposition, with China and Russia’s acquiescence. South Korea then must acquire nuclear latency, first by revising the ROK-U.S. nuclear agreement and, in the worst-case scenario, convincing the White House that a conditional, U.S.-friendly nuclear armament for the purpose of denuclearization talks is inevitable.

A Burden-Sharing Alliance

The United States is considerably fatigued by its role as a “global policeman,” arousing international skepticism about U.S. power projection abroad. As a result, it will become increasingly challenging for South Korea to maintain its current defense policy, which almost solely depends on the ROK-U.S. alliance for Seoul’s potential national security crises. If Seoul’s defense-sharing costs continue to rise to re-introduce American tactical nuclear arms or more frequent visits to strategic nuclear delivery platforms, South Koreans will become more critical of the U.S. nuclear umbrella’s costs.

South Korea has the capacity not only to confront North Korea but also to be more active in supporting the United States against challenges to the international order, considering its close proximity to states opposed to U.S. hegemony. Therefore, it is crucial to emphasize that South Korean nuclear capabilities would strategically contribute to the alliance. A moderately sized South Korean nuclear arsenal would be committed to burden-sharing and responsible diplomacy.

Transforming the characteristics of the ROK-U.S. alliance is essential. The White House bears unique security risks in providing Seoul with a nuclear umbrella. Allies in Asia and Europe are accustomed to peace under the international order established by the United States; those in NATO, for example, have enjoyed a cost-effective defense since the deployment of American tactical nuclear forces. Similarly, South Korea has taken the nuclear umbrella for granted even though it is the basis of its national survival. Instead, if the ROK-U.S. alliance could be upgraded to a “strategic nuclear-based alliance” in the future with South Korea’s nuclearization, the Korean and American presidents could consider joint visits to each other’s nuclear forces as a new security solution against both Chinese and North Korean nuclear build-up.

Washington’s vital national interest lies in deterring a rising challenger state. It is also important to note that the United States was initially against all nuclear proliferation, then reversed course by tolerating various states’ nuclear weapons and starting nuclear cooperation. Since then, the United States has focused on actively preventing proliferation in adversarial states.

UN: Realistic Perception about International Regimes

South Korea’s potential exit from the Non-Proliferation Treaty (NPT) under Article 10 is feasible, but Seoul must address the United States’ concerns about undermining the NPT regime. If Seoul were to withdraw, ROK officials would send a clear message to global audiences, defining the current regional security situation as an unprecedented existential threat to their country’s national survival and justifying their actions as their right to self-defense.

North Korea withdrew from the treaty to secure the Kim family’s authority and regime. In contrast, South Korea presents a legitimate case for self-defense in response to its neighbors’ aggressive build-ups. South Korea’s nuclear diplomacy needs to emphasize the risks to global nuclear security, including authoritarian regimes’ active nuclear weapons acquisition, illegal proliferation, and coercive use of nuclear assets.

Sovereign countries can defend themselves, as Article 51 of the UN Charter clearly recognizes. The right of self-defense can be interpreted to include nuclear armament. None of the Western states that experienced clear and present dangers in history has ever abandoned the nuclear option. Even in peacetime, most states have maintained and improved their nuclear arsenals to survive and deter hostile nuclear first strikes.

All nuclear powers have possessed such strategic weapons for defensive purposes. The invasion of Iraq and Israel’s pre-emptive strikes on neighboring nuclear reactors were recognized as defensive operations to prevent future dangers and accepted by the international community as such. There is no compelling reason why South Korea, which is currently facing several nuclear-armed adversaries, should be deprived of the same right.

South Korea needs to formulate a nuclear diplomatic strategy emphasizing the incentives its nuclear arsenal could offer the alliance. Concurrently, Seoul must propose a new legally binding framework covering a range of safety measures to reassure Washington that South Korean nuclear capabilities will not necessarily lead to a breakdown of bilateral relations under any circumstances. Subsequently, the White House could align South Korea’s nuclear arsenal with its alliance-based grand strategy.

Yulgok Kim is the Secretary General of the Republic of Korea’s Forum for Nuclear Strategy (ROKFNS). His Twitter is @rokfns.