Should South Korea develop nuclear weapons?

31 October 2023

South Korean President Yoon Suk-yeol’s comment earlier this year on the possibility of initiating an indigenous nuclear programme implies Seoul’s profound threat awareness from nuclear-armed North Korea.

The comment catalysed the Washington Declaration, which reaffirmed that the United States would use its nuclear arms only when the White House deems it necessary, emphasising that even close allies cannot be involved in its decision-making process for nuclear retaliation. The vague declaration aroused scathing criticism in South Korea for failing to offer a specific blueprint against China and North Korea.

Washington’s nuclear policy must face the fact that extended deterrence can no longer appease South Korea’s anxiety and curb its desire for national survival. China's willingness to influence North Korea towards denuclearising is decreasing, and Pyongyang is unlikely to abandon its nuclear arsenal. The nuclear umbrella is flawed by its nature because it is unprepared for a situation where the US might prefer to use only conventional firepower instead of equivalent nuclear retaliation in response to North Korean strategic nuclear strikes on Seoul. Watching the wars in Ukraine and Israel unfold, it is natural for the US’ allies to wonder whether the nuclear-armed great power would be willing to risk its urban mainland and retaliate without hesitation.

‘America First’ and North Korea’s offensive nuclear doctrine

No matter how much the US endeavours to reassure its allies regarding its nuclear umbrella and the decades-long ROK-US alliance, security anxiety continues to linger in Seoul. The common sense that a rational US president would not be able to risk massive nuclear destruction of Washington, DC and other metropolitan cities in a nuclear crisis makes the scepticism of extended deterrence enduring and reasonable.

South Korea's nuclear development has been an unthinkable taboo for decades, but North Korea's upgrading nuclear capabilities requires a policy shift.

Seemingly, the US security commitment to the Korean Peninsula is rock-solid. However, history has demonstrated that the US does not always deliver on its promise of proxy defence. Washington abandoned Vietnam in the 1970s after ten years of a local war in which the US spent an astronomical budget and sacrificed almost 60,000 soldiers. The Biden administration withdrew all US forces from Afghanistan after spending USD 1 trillion. Donald Trump requested that South Korea pay significantly more than double the defence-sharing costs for providing a nuclear umbrella and American troops in Korea, while trying to sign a peace treaty with Kim Jong Un at all costs. The East Asian security situation is too complicated for Seoul to rely only on American presidents with term limits, who regularly change regional security doctrines and policies. Seoul considers the Washington Declaration and Camp David joint statement symbolic gestures, but the diplomatic rhetoric may not be enough to allay the North Korean and Chinese nuclear threats.

Another factor that increases uncertainty is the sustainability of bilateral agreements and the tendency for foreign policy priorities to vary across administrations. For example, the United States temporarily gave up its non-proliferation principle to support Australian nuclear-powered submarines as part of AUKUS. Additionally, with Washington occupied with managing the war in Ukraine and escalating violence in the Middle East, Korean affairs may be a lower priority on the US’ foreign policy table. If North Korea decides to take advantage of this situation to coerce South Korea offensively, it would be too challenging for Seoul and Washington to deal with such a crisis immediately.

Pyongyang does not flinch now even when American strategic assets visit South Korean air bases and ports, firing missiles targeting them to increase regional instability and uncertainty. North Korea has acquired limited second-strike capabilities by developing submarine-launched ballistic missiles (SLBM). South Korea and Japan are already within easy firing range of North Korean nuclear weapons. Kim Jong Un has tried to advance sea-based nuclear weapons to complete his nuclear deterrent against the US mainland, creating a question of assurance between Washington and Seoul. The US judges North Korean capability to target American territory to be not yet entirely credible. Moreover, Washington tends to believe that extended deterrence to East Asia is sufficient as it is relatively less desperate than Seoul, which is right under Kim’s short-range nuclear strike possibilities. Moreover, the North Korean declaration on the first use of nuclear weapons against both the US and key allied states amplifies non-nuclear states’ anxiety over uncertainty. Pyongyang intends to use South Korea as a target for a nuclear first strike in any defined situation.

Cracks in the non-proliferation regime

The goal of the NPT is ultimately to reduce the nuclear weapons stockpiles of the five internationally acknowledged nuclear-armed states. However, suppose the Chinese nuclear build-up continues, and the United States fails to curb both Chinese and North Korean nuclear advancement while oppressing allies’ justifiable instinct for survival. In that case, non-nuclear American allies’ sense of vulnerability will be worsened, triggering a domino effect that would lead Seoul and Tokyo to pursue their own nuclear programmes.

Even though the United States has externally maintained a non-proliferation policy since the advent of the NPT, the process has failed. Washington had to tolerate Indian and Pakistani nuclearisation outside the treaty for geopolitical gains, such as the war on terrorism and balancing China; North Korea is now following suit. The White House took a selective measure to provide Australia with nuclear submarines to quash the Chinese hegemonic rise while restraining South Korea’s nuclear debate. In other words, ironically, non-nuclear allies relying on the US nuclear umbrella will soon be threatened by the nuclear weapons of authoritarian states China and Russia.

The G7 agreed in Hiroshima that the NPT is the foundation of the international non-proliferation regime and reiterated its commitment to preventing nuclear proliferation. However, China and Russia are expanding their nuclear arsenals despite ban treaties. For instance, Beijing is expected to possess more than 1,000 nuclear warheads by the 2030s. North Korea's nuclear arsenal is projected to grow to 200 warheads by 2027, far exceeding the combined nuclear arsenals of Pakistan, India, and Israel. If the US initiated nuclear arms reduction talks with Pyongyang, a bilateral peace treaty or an arms reduction agreement would reduce the nuclear threat to the US mainland. For South Korea, however, it would mean the continuation of its position as a nuclear hostage state.

Next step for the ROK-US alliance: nuclear latency

Not only the ruling party but also opposition leaders and former government officials who disagree with South Korea pursuing an indigenous nuclear programme have reached a consensus that South Korea needs nuclear latency by revising the ROK-US nuclear agreement. The current ROK-US nuclear agreement and the NPT do not properly reflect South Korea's insecurity from Sino-North Korean nuclear threats and the changed volatile circumstances. Therefore, revising the nuclear agreement would be a cornerstone to achieving a nuclear threshold state position and adjusting South Korean security strategy in proportional response to North Korea's and China's actions.

South Korea’s role model in nuclear strategy could be Japan, a nuclear threshold state, which convinced Washington that it could acquire nuclear latency in the NPT framework. Japan revised the US-Japan nuclear agreement in 1987 to comprehensively agree to the reprocessing of nuclear wastes in Japan, as per Articles III and V of the agreement, enabling Tokyo to practically have the ability to go nuclear within six months. For President Yoon's "nuclear weapons in a year" slogan to come true, Seoul needs first to secure its nuclear potential within the treaty, as right now the US’ main priority is close trilateral cooperation between the United States, South Korea, and Japan.

South Korean political parties cannot ignore the mainstream pro-nuclear public opinion. More than 70 per cent of the public favours nuclear armament. South Korea's nuclear development has been an unthinkable taboo for decades, but North Korea's upgrading nuclear capabilities requires a policy shift. The shift can only begin with acknowledging the complexity of denuclearising North Korea and accepting the new reality that South Korean nuclear weapons will be defensive for deterrence.

DISCLAIMER: All views expressed are those of the writer and do not necessarily represent that of the 9DASHLINE.com platform.

Author biography

Yulgok Kim is the 2nd Secretary General of the ROK Forum for Nuclear Strategy (ROKFNS). As a Korean security researcher and a defence columnist, Kim writes analyses and op-eds, some of which were published by The National Interest. He focuses on Asia-Pacific affairs, nuclear security, South Korean foreign policy, and national security strategy. Image credit: Flickr/The White House.