TheUnited Statesstationed variousnuclear weapons and theirdelivery systems inSouth Korea between 1958 and 1991. South Korea actively pursued a nuclear weapons program from 1970 to 1981, primarily undermilitary dictatorPark Chung Hee. South Korea signed theNon-Proliferation Treaty in 1975, but conducted illegal nuclear weapons-related experiments until 2000. South Korea benefits from the United States'nuclear umbrella as part of thecountries' close alliance. South Korea is aratifier of theBiological Weapons Convention andChemical Weapons Convention, disposing of itsCold War-erachemical weapons stockpile by 2008.^[1] South Korea's policy on weapons of mass destruction is heavily influenced by its perception ofNorth Korea's nuclear, chemical, and biological weapons.^[2]

South Korea has the resources, equipment, and technical ability to quickly develop a nuclear weapons capability, a status known asnuclear latency.^[3] This includesan advanced nuclear power industry, and theHyunmoo series ofballistic andcruise missiles; South Korea is the only non-nuclear-armed country to possesssubmarine-launched ballistic missiles. North Korea has possessed nuclear weapons sinceits first nuclear test in 2006, and continues totest nuclear-capable missiles.

South Korean policy maintainsnon-proliferation of nuclear weapons and the goal of a nuclear-freeKorean Peninsula. However, as of 2023^[update], a majority of South Koreans consistently favor nuclear weapons development, and politicians have expressed consideration for such a program.

In August 2004, South Korea revealed the extent of its highly secretive and sensitive nuclear research programs to theInternational Atomic Energy Agency (IAEA), including some experiments which were conducted without the obligatory reporting to the IAEA called for by South Korea's safeguards agreement.^[4] The IAEA Secretariat reported the failure to report to IAEA Board of Governors.^[5] However, the IAEA Board of Governors decided to not make a formal finding of noncompliance.^[6]

When the United States notified the South Korean administration of its plan to withdrawUSFK in July 1970, South Korea first considered the possibility of an independent nuclear program. Under the direction of South Korea's Weapons Exploitation Committee, the country attempted to obtainplutoniumreprocessing facilities following the pullout of the 26,000 American soldiers of the7th Infantry Division in 1971.^[7] After South Vietnam had fallen in April 1975, then South Korean presidentPark Chung Hee first mentioned its nuclear weapons aspiration during the press conference on 12 June 1975.^[8] However, under pressure from the United States, France eventually decided not to deliver a reprocessing facility to South Korea in 1975.^[7] South Korea's nuclear weapons research program effectively ended on April 23, 1975, with its ratification of the Nuclear Non-Proliferation Treaty.^[7] According to a 2017 literature review of worldwide nuclear programs, South Korea actively pursued nuclear weapons from 1970 to 1981, first exploring the possibility in 1969.^[9]

In 1982, scientists at the Korean Atomic Energy Research Institute performed an experiment in which they extracted several milligrams ofplutonium. Although plutonium has uses other than the manufacture of weapons, the United States later insisted that South Korea not attempt to reprocess plutonium in any way. In exchange, the US agreed to transfer reactor technology and give financial assistance to South Korea's nuclear energy program. It was revealed in 2004 that some South Korean scientists continued some studies; for example, in 1983 and 1984 Korea Atomic Energy Research Institute was conducting chemical experiments related to the handling of spent fuel that crossed the reprocessing boundary.^[10]

Later, in an experiment at the same facility in 2000, scientists enriched 200 milligrams ofuranium to near-weapons grade (up to 77 percent) usinglaser enrichment.^{[10][failed verification][11][full citation needed]} The South Korean government claimed that this research was conducted without its knowledge.^[12] While uranium enriched to 77 percent is usually not considered weapons-grade, it could theoretically be used to construct a nuclear weapon.^[13][14]Highly enriched uranium with a purity of 20% or more is usable in a weapon, but this route is less desirable as far more material is required to obtain critical mass.^[15]

These events went unreported to the IAEA until late 2004.^[10]

Following Seoul's disclosure of the above incidents, the IAEA launched a full investigation into South Korea's nuclear activities. In a report issued on November 11, 2004, the IAEA described the South Korean government's failure to report its nuclear activities a matter of "serious concern", but accepted that these experiments never produced more than very small amounts of weaponizable fissile material. The Board of Governors decided to not make a formal finding of noncompliance, and the matter was not referred to the Security Council.^[6]

Pierre Goldschmidt, former head of the department of safeguards at the IAEA, has called on the Board of Governors to adopt generic resolutions which would apply to all states in such circumstances and has argued "political considerations played a dominant role in the board's decision" to not make a formal finding of non-compliance.^[16]

The US first deployed nuclear weapons to South Korea in 1958,^[17] and withdrew them in 1991.^[18] Numbers peaked in the late 1960s at close to 950, including a mix of tactical and strategic weapons.^[19][20] In July 2023, theUSS Kentucky nuclear-armedballistic missile submarine made a port call atBusan Naval Base, temporarily returning nuclear weapons to South Korea for the first time in 32 years.^[21]

Following its accession to theNuclear Non-Proliferation Treaty in 1985, the government ofNorth Korea had cited the presence of UStactical nuclear weapons in South Korea as a reason to avoid completing a safeguards agreement with theInternational Atomic Energy Agency.^[22] In 1991, PresidentGeorge H W Bush announced the withdrawal of all naval and land-based tactical nuclear weapons deployed abroad, including approximately 100 such weapons based in South Korea.^[23] In January 1992, the governments of North and South Korea signed aJoint Declaration of the Denuclearization of the Korean Peninsula, and in January 1992, the North concluded a comprehensive safeguards agreement with the IAEA.^[22] Implementation meetings for the Joint Declaration took place in 1992 and 1993, but no agreement could be found, so consequently the declaration never entered into force.^[24][25]

In 2013, South Korean Prime MinisterChung Hong-won rejected calls to again station Americantactical nuclear weapons in South Korea.^[26]

In 2017, during a period ofunusually high tension with North Korea,South Korean defence ministerSong Young-moo suggested it was worth reviewing the redeployment of U.S. nuclear weapons to the Korean Peninsula.^[27]

Yoon Suk-yeol, the incumbent President of South Korea, stated in 2021 that he would ask that the United States redeploytactical nuclear weapons in South Korea.^[28]

In 2023, South Korea agreed not to develop nuclear weapons in exchange for American deployment of nuclear-armed submarines in South Korea.^[29]

In 2025, a South Korean declassified document confirmed that Russia offered nuclear programs to repay debt inherited from the Soviet Union. In 1992, Russia offered advanced nuclear and plant life-extending technology. In 1994, Russia offered 50 tons of highly enriched uranium originating from Ukrainian nuclear warheads plus 150 tons of low-enriched uranium annually for 10 years.^[30][31]

In the late 1990s, a notable minority of South Koreans supported the country's effort to reprocess materials, although only a small number called for the government to obtain nuclear weapons.^[32]

With the escalation of the2017 North Korea crisis, amid worries that the United States might hesitate to defend South Korea from a North Korean attack for fear of inviting a missile attack against the United States, public opinion turned strongly in favour of a South Korean nuclear arsenal, with polls showing that 60% of South Koreans supported building nuclear weapons.^[33]

In a 2023 poll, over 76% of South Koreans support the indigenous development of nuclear weapons.^[34][35][36]

Although currently, South Korea is under the US nuclear umbrella of protection, it could very well break away and try to develop its own nuclear weapons if necessary. Like Japan, South Korea has the raw materials, technology, and resources to create nuclear weapons. Previous incidents show the Republic of Korea (ROK) to be able to possess nuclear weapons in anywhere from one to three years if necessary. The ROK has been shown before to create enriched uranium up to 77%, which, although not particularly powerful, shows that South Korea has the potential to make nuclear weapons with more highly enriched uranium. South Korea does not have anyintercontinental ballistic missiles but possesses a wide range ofshort-range andmedium-range ballistic missiles through theHyunmoo series of ballistic/cruise missiles currently fielded by the ROK Army and the ROK Navy. TheHyunmoo series of ballistic/cruise missiles works similarly to the AmericanTomahawk Missile, which can be armed with the W80 and W84 nuclear warheads. Theoretically, if needed, the 500 kg conventional warhead could be replaced by a small nuclear warhead. The Hyunmoo missiles can already cover the entire range of North Korea and would drastically change the North's disposition if the South had nuclear-armedMRBM/LACMs. Even though the ROK could procure nuclear weapons, currently like Japan, it sees no reason to do so with the protection of the American nuclear arsenal. However, if a conflict erupts with the North, South Korea could quickly evolve into a nuclear-armed state and pose even with the North with the support of the US.^[37] According to Suh Kune-yull, a professor ofnuclear engineering atSeoul National University, “If we decide to stand on our own feet and put our resources together, we can build nuclear weapons in six months”.^[38]

South Korean presidentYoon Suk Yeol stated in January 2023 that if the security situation regarding the threat from North Korean nuclear weapons deteriorates further, South Korea would consider building their own nuclear weapons to deter the North or request that the United States deploy nuclear weapons in South Korea. In 1991 the United States removed all of its nuclear weapons from South Korea. The statements from the South Korean president came during a policy briefing by his foreign and defense ministries; the comments are the first time South Korea has officially acknowledged they would consider developing its own nuclear arsenal in response to North Korean nuclear weapons.

In 2022 South Korea announced it had developedsubmarine-launched ballistic missiles,Hyunmoo-4-4; South Korea is the only nation with SLBMs that does not possess nuclear weapons.^[39][40][41]

In February 2023, the leader of thePeople Power Party,Chung Jin Suk said that South Korea might need nuclear weapons.^{[42][43][44][45][46][36]}

In March 2023,Mayor of SeoulOh Se-hoon called for South Korea to have nuclear weapons.^[47][48]

South Korea missile development originates in 1970 with creation of Defense Ministry'sAgency of Defense Development with development starting in 1971 under orders of then president Park Chung Hee.

In 1970 South Korea was allowed to service MIM-23 Hawk and MIM-14 Nike Hercules surface-to-air missiles under agreement with maintenance facilities under the supervision of the U.S. which was set up in the country with South Korean engineers receiving training fromRaytheon and U.S. military involving improvement of the missiles.

In 1975 South Korea purchased mixer for missiles' solid fuel propellant from Lockheed along with some equipment imported later on. 1978 marked the first successful ballistic missile test of the first South KoreanSRBM NHK-1(also known as White/Polar Bear) conducted on September 26, demonstrating 160 km range with maximum range of 180 to 200 km. NHK-1 was touted by South Korea as a completely indigenous development, though in fact some of the technology was supplied and obtained from the United States.

Seoul agreed to not extended range of the missile beyond 180 km underSouth Korea Ballistic Missile Range Guidelines with the U.S. with development of its successorNHK-2 that was tested in October 1982 with development being halted in 1984 until its resumption a couple years later with its completion in 1987 when it entered service, its guidance system was supplied by United Kingdom. In 1995 South Korea requested permission to have 300 km range missiles from the US in line withMTCR with request in 1999 for expansion to 500 km.^[49] Development of 300 km rangeHyunmoo-2 started in mid to late 1990s with first test in April 1999 with entering service in 2008 as Hyunmoo-2A after restrictions were lifted from previous agreement to limitation comparable to MTCR,^[50] Hyunmoo-2B entered service in 2009 with range under MTCR-like restriction as well as range restriction underSouth Korea Ballistic Missile Range Guidelines renegotiated in 2012 with the US from 300 km to 800 km with reduced payload from 997 kg to 500 kg.^[51] The cap on missile warhead weight was lifted in 2017.^[52]

On May 21, 2021, the decades-oldSouth Korea Ballistic Missile Range Guidelines was scrapped, allowing South Korea to develop and possess any type of missile, includingintercontinental ballistic missiles (ICBMs) and advancedsubmarine-launched ballistic missiles (SLBMs).^[53][54]

South Korea formerly held thechemical weapons stockpile of 3,000–3,500 metric tons (3,300–3,900 short tons) but disposed of it by July 2008.^[1]

South Korea signed theChemical Weapons Convention in 1993 and ratified it in 1997.^[55]

South Korea signed theBiological Weapons Convention in 1972 and ratified it in 1987.^[56]

• International Atomic Energy Agency
• North Korea nuclear weapons program
• Nuclear power in South Korea
• Nuclear Non-Proliferation Treaty
• South Korea Ballistic Missile Range Guidelines
• Timeline of the North Korean nuclear program
• ko:대한민국의 핵무기 개발
• ko:대한민국의 독자 핵무장론

• "South Korea happy with IAEA report on past N-experiments".The Nation (Pakistani newspaper). Archived fromthe original on November 16, 2004. RetrievedApril 2, 2005.
• "South Korea's Big Stick".Ethiopundit. September 14, 2004. RetrievedApril 2, 2005.
• "South Korea's Nuclear Experiments".Center for Nonproliferation Studies. November 9, 2004. Archived fromthe original on June 23, 2006. RetrievedJune 26, 2006.
• "South Korea's Nuclear Mis-Adventures".Nautilus Institute. September 10, 2004. Archived fromthe original on February 19, 2006. RetrievedJune 26, 2006.
• "Countries of Strategic Nuclear Concern - South Korea".Stockholm International Peace Research Institute. Archived fromthe original on June 21, 2006. RetrievedJune 26, 2006.
• "South Korean Nuclear History".Wilson Center Digital Archive. Retrieved23 March 2014.

• South Korea Nuclear Chronology; Nuclear Threat Initiative

• Weapons of mass destruction by country
• Government of South Korea
• Military history of South Korea
• Nuclear technology in South Korea
• Science and technology in South Korea
• Nuclear weapons programs

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