Should South Korea build the nuclear bomb?

As of 2026, North Korea defines its relationship with South Korea not as one between fellow Koreans but as “hostile two-state relations”. It pursues a two-pronged strategy: abandoning the concept of unification and the notion of a nation, while simultaneously applying military pressure through the operationalisation of its nuclear forces against South Korea.

In doing so, North Korea is solidifying its parallel development of nuclear and conventional capabilities, advancing its nuclear and missile capabilities across tactical nuclear weapons, intercontinental ballistic missiles (ICBMs) and submarine-launched ballistic missiles (SLBMs). All in all, North Korea’s strengthening of its operational nuclear capabilities poses a major threat to South Korea’s security. 

The nuclear domino effect refers to the chain reaction where neighbouring countries, perceiving security threats, choose to acquire nuclear weapons once one state possesses them. Indeed, due to the heightened North Korean threat and instability in the international situation, domestic support for nuclear armament in South Korea is trending upward. 

According to the latest survey by the East Asia Institute (EAI) in Seoul, based on the results of the 2025 EAI East Asia Perception Survey released in February 2026, 75.1% of respondents agreed that “South Korea should pursue nuclear armament if North Korea refuses to abandon its nuclear weapons”. The high approval rate stems from distrust in whether the US would defend South Korea at the risk of its own homeland being attacked. North Korea’s nuclear capabilities have evolved, including the potential for military technology transfers from Russia. A nationalistic security perspective has spread across all age groups in South Korea. 

Consequently, international concerns about South Korea’s potential nuclear armament and development ambitions as the first nuclear domino are significant. In the Global Foresight 2025 survey conducted by the US think tank Atlantic Council in February 2025, targeting 357 global strategists and experts from 60 countries, South Korea (40.2%) was ranked third as a country most likely to acquire nuclear weapons within the next decade, following Iran (72.8%) and Saudi Arabia (41.6%).

However, South Korea faces multiple challenges in developing its own nuclear weapons. Domestically, while South Koreans generally view nuclear armament as necessary, they remain realistically concerned about the economic and diplomatic costs it would entail. Withdrawing from the International Atomic Energy Agency (IAEA) or the Non-Proliferation Treaty (NPT) would likely trigger massive international economic sanctions, diplomatic isolation and risks of financial and trade shocks. 

South Korea’s high trade dependency makes sanctions risks particularly devastating. An October 2025 survey by the Korea Institute for National Unification of 52 security experts in South Korea found 11.5% believed nuclear armament was necessary, while 46.5% deemed it unnecessary. Experts cite strengthening the US-ROK alliance and solidifying extended deterrence against North Korea as more effective responses to the North Korean nuclear threat than nuclear armament. 

Externally, if South Korea nuclearises, Japan could rapidly follow suit based on its plutonium stockpile. Should Taiwan join this trend, China would likely view it as the collapse of the “nuclear-free order in Northeast Asia”. The entire region would become a nuclear powder keg, completely shattering the strategic balance between the US and China. Should a nuclear domino effect materialise, the NPT, maintained for decades, would effectively reach the end of its lifespan. 

Perhaps, South Korea’s most realistic choice is a cost-effective hybrid strategy rather than immediate nuclear armament. The immediate option is the rotational deployment of US strategic assets. Permanent deployment or NATO-style nuclear sharing would be perceived by China not merely as defence of the Korean peninsula, but as a forward-deployed system targeting its own mainland. 

Second, maximise conventional deterrence while excluding nuclear weapons. In other words, possess a three-axis system (Kill Chain, Korean Air and Missile Defense (KAMD), Korea Massive Punishment and Retaliation (KMPR) capable of neutralising an adversary’s nuclear capabilities before they can use theirs, along with SLBMs, high-yield ballistic missiles and nuclear-powered submarines. It employs cyber and space domain strategic weapons to disrupt satellites and GPS, paralysing the adversary’s national infrastructure, and delivers decisive retaliation through a submarine-based system equipped with SLBMs.

Third, the most viable option is the Japanese-style nuclear threshold state strategy. This involves maintaining the technological, material and human resources base to produce nuclear weapons at any time without actually building them, while retaining enrichment and reprocessing capabilities without weaponising them. 

However, the current Lee Jae-myung administration is operating more pragmatically, grounded in realistic sensibilities. Blocking a nuclear domino effect in Northeast Asia and promoting sustained peace requires a complex, multi-layered approach that transcends mere military deterrence. Options range from short-term crisis management to building long-term multilateral security cooperation frameworks. 

Models like NATO or a Northeast Asian security mechanism appear unrealistic for the foreseeable future. The motivation for peace maintenance through economic interdependence is also losing persuasiveness, much like the securitisation of the economy through industrial and supply chains.

The current Lee administration’s goal for its “Korean Peninsula Peaceful Coexistence Policy” is to pursue inter-Korean peaceful coexistence and a nuclear-free Korean peninsula, advancing exchanges, normalisation of relations and denuclearisation in a phased and comprehensive manner. Long-term, it aims for a nuclear-free Korean peninsula, but short-term, it prioritises blocking nuclear advancement and managing threats. It seeks to reopen the door to negotiations by exchanging a freeze on nuclear weapons and ICBMs for corresponding partial sanctions relief. While not abandoning denuclearisation, it aims to reduce risks through freeze and reduction measures and establish a path toward gradual reduction, given the difficulty of achieving a comprehensive settlement in the short term. 

As tensions persist on the Korean peninsula, military uncertainty grows and regional competition intensifies. Conversely, halting nuclear advancement and resuming negotiations would contribute to stability across Northeast Asia. At this juncture, the Lee administration intends to align with the Trump administration’s “strengthening of allied responsibilities” policy, pursuing a direction that enhances the technological capabilities and self-reliant defence capacity of the ROK military rather than relying solely on US strategic assets. 

Through agreements with the US, it seeks to secure tangible nuclear potential for the ROK military, such as building nuclear-powered submarines and expanding uranium enrichment capabilities. Simultaneously, South Korea, currently acting as a pace setter, actively supports direct US-North Korea dialogue as a peacemaker. 

Meanwhile, cooperation with China is also critically important. Peace and stability on the Korean peninsula are closely intertwined with China’s security and economic interests. China, with its unique relationship with North Korea, occupies the position not merely of an observer but of a facilitator and coordinator of dialogue. If a phased approach acknowledging reality is pursued, China’s constructive mediation could be decisive in creating a favourable negotiation environment. 

In conclusion, what the Korean peninsula most urgently needs now is the management of its current instability and the restart of negotiations. The path beginning with freeze and reduction may seem distant, but it may well be the most realistic first step. Korean peninsula denuclearisation is not an ideal or a dream; it must pass through reality.

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