11 April 2025
CO25077 | The Nuclear Question for South Korea Amidst the Shifting Geopolitics of the Korean Peninsula
SYNOPSIS
North Korea’s nuclearisation and US foreign policy shifts under the second Trump administration have raised security concerns in South Korea. With rising scepticism about US security guarantees, domestic debates on South Korea’s nuclearisation and how it manages the North Korean security threat have intensified. Besides these issues, this article also examines the strategic dilemmas, the economic impact, diplomatic options, policy implications, and the future of US-South Korea-North Korea relations.
COMMENTARY
The Democratic People’s Republic of Korea (DPRK or North Korea) conducted its first nuclear test in 2006, followed by a series of missile tests. North Korea’s nuclearisation, missile tests, and nuclear threats against the Republic of Korea (ROK or South Korea) have been a grave security concern to East Asia.
The 1953 partition of the Korean Peninsula marked the beginning of a persistent rivalry between the two states, leaving them perpetually in a state of heightened tensions. While both governments have sought eventual reunification, their security concerns, trust deficits, and weak commitment towards conflict resolution have contributed to bilateral tensions and insecurity in the wider Indo-Pacific.
The United States has played a significant role in the geopolitics of the Korean Peninsula following the end of the Korean War through the 1953 US-ROK Mutual Defence Treaty, which guarantees the latter a place under the US security umbrella. The deployment of 29,000 US troops in South Korea aims to defend it and deter aggression from North Korea.
Under the Non-Proliferation Treaty (NPT), both North Korea and South Korea have since maintained the status of Non-Nuclear Weapons States, focusing on a normative approach of non-nuclearisation and prioritising economic growth. North Korea left the NPT in 2003 and went on to develop its nuclear and missile programme. Between 2017 and 2024, it conducted six nuclear tests and many missile tests of short, long, and intercontinental-range missiles, despite heavy sanctions from the West. Pyongyang’s relations with Tokyo have deteriorated as a result of its missile firing over Japan and its territorial waters, which were violations of international law.
The involvement of external powers like the US, China, Russia, and Japan in the Korean conflict has complicated conflict resolution efforts between the ROK and DPRK.
US Foreign Policy and the Trump Factor
Over the last few decades, the United States has made several attempts at denuclearising North Korea through various means, including the use of sanctions, sanction waivers, and diplomacy, such as the so-called Six-Party talks involving the ROK, DPRK, US, Japan, China and Russia. For instance, its negotiations with North Korea between 1999 and 2019 were aimed at getting the latter to agree to a nuclear moratorium, to abandon the pursuit of nuclear weapons, and to deter it from engaging in further nuclear activities.
Since 2009, the US has attempted to reengage in diplomatic negotiations with North Korea, including the Obama administration’s US-DPRK bilateral talks between January 2009 and January 2017 and the Six-Party talks. Apart from a brief suspension of North Korea’s nuclear programme, no significant success in denuclearisation was achieved.
During the first Trump administration, significant attempts were made between January 2017 and January 2021 to negotiate with North Korea’s President Kim Jong-Un. While President Trump became the first serving American president to step foot in North Korea in 2019, and the US-DPRK bilateral talks in Singapore (2018) and Vietnam (2019) led to agreements on lasting peace, no progress was achieved on the abandonment of Pyongyang’s nuclear ambitions.
From January 2021 to January 2025, the succeeding Biden administration promised North Korea complete relief from sanctions in return for complete denuclearisation, with no reciprocal commitment by the latter. The US signed a classified “nuclear guideline strategy” with South Korea, reaffirming its commitment to defend it in the event of a nuclear attack from North Korea. Under this strategy, US nuclear weapons would be deployed on the ground and around South Korea to respond to a potential nuclear attack by North Korea. This guideline strategy notwithstanding, the ROK is not confident that it will survive future changes of US administrations.
Thus, North Korea’s engagement with the US, involvement in the Six-Party talks and the ROK-DPRK dialogues have led to Pyongyang receiving measured sanctions relief from the US without it having to commit to denuclearisation. Moreover, its relentless nuclear and missile testing programmes have dented the probability of peace between the two Koreas and challenged US foreign policy and its strategic approach to the peninsula’s security crisis.
The re-election of Donald Trump has raised more concerns and insecurity in Seoul because of his unpredictability and looming questions over the reliability and continuity of the US security guarantee for the region. As a result, South Korea’s political leadership have been driven to reconsider its non-nuclear nation status and whether it should develop an independent nuclear capability as a deterrence against the North Korean nuclear threat.
Debates on the Nuclearisation of South Korea
Domestic opinion on whether South Korea should acquire nuclear weapons is divided. According to a 2022 survey by the Chicago Council on Global Affairs, there was overwhelming support for South Korea’s nuclearisation, with approximately seven out of ten South Koreans preferring the nation to develop its own nuclear weapons and about 67 per cent opting for an independent arsenal. On the other hand, 26 per cent opposed South Korea’s nuclearisation, and four in ten opposed the US deployment of nuclear weapons. Similar sentiment was demonstrated in the 2024 survey by the Korea Institute for National Unification where six in ten South Koreans favoured having nuclear weapons if DPRK does not denuclearise.
Rising domestic support for South Korea’s nuclearisation stems from the security threats posed by Pyongyang and Beijing, the ambiguity of US foreign policy, and its relative inaction in reaffirming the security guarantee for the Korean peninsula. North Korea’s frequent sabre rattling also created pressure in negotiations. Possessing nuclear weapons could provide the required leverage for South Korea at the negotiating table. Donald Trump’s re-election has accelerated these debates, increasing the view that nuclearisation is becoming more necessary than ever.
Those against South Korea’s nuclearisation doubt that North Korea would ever use its nuclear weapons, given the risk of self-destruction from the irradiation. They view its acquisition of the weapons as a means to ensure regime survival. They have also argued that it would damage the normative and ethical fabric underlying Seoul’s anti-nuclearisation policy and could drive a nuclear arms race, greatly diminishing the prospects for the peninsula’s denuclearisation or peaceful unification.
Furthermore, in leaving the NPT, South Korea could also face similar sanctions as North Korea from neighbouring countries and allies, undermining its domestic and regional economic growth. Thus, the denuclearisation of the Korean Peninsula is considered an issue to be resolved through dialogue and negotiations, alongside efforts to deter Pyongyang from conducting nuclear tests.
The Way Forward
Dialogue between Seoul and Washington is essential to finding common ground on Korean security and regional stability. It is not feasible for South Korea to start an independent nuclear programme while maintaining its military alliance with the US.
The US needs to build trust with South Korea by reaffirming its security guarantee and commitment to the Biden administration’s “nuclear guideline strategy”. It also needs to successfully negotiate with North Korea to abandon its nuclear threats, cease its missile programme, and engage in inter-Korean peace dialogue.
As an alternative to developing nuclear weapons, South Korea could work out a semi- or de facto nuclear-powered arrangement with the US to maintain deterrence capabilities without testing nuclear weapons. A model involving South Korea, the US and other regional allies similar to that of AUKUS could be an option. However, that could also stir insecurity among Seoul’s adversaries and strategic rivals.
South Korea has also sought a tariff waiver for its 2.5 million tonnes of steel exports to the US following the latter’s announcement of a 25 per cent tariff on steel and metal products on all countries. Attempting to develop a nuclear capability will also disrupt South Korea’s relations with export destinations such as China, Vietnam, Japan, Hong Kong, Taiwan, Singapore, India, Australia, Mexico, Germany and Malaysia. It could also cause damage to the electronics sector and supply chains in the Indo-Pacific, which would force the US to take a position to protect its supply chains from disruptions while preserving US and global economic interests.
Finally, the unification of the Korean Peninsula has been an ultimate objective for both South Korea and North Korea. However, the involvement of extra-regional actors has made the situation more complex and inconducive to conflict resolution. Therefore, the ROK-DPRK bilateral dialogue without third-party big power interference is crucial, while regional geopolitical actors like Japan, India, Australia and Indonesia can provide informal support.
About the Authors
Dr Astha Chadha is an Associate Professor at Ritsumeikan University in Kyoto, Japan, and the author of Faith and Politics in South Asia (Routledge: 2024). Nihar Kulkarni is a PhD researcher at the Faculty of Political Science and International Studies, University of Warsaw, Poland. Both specialise in geopolitics and security dynamics in the Indo-Pacific region.
SYNOPSIS
North Korea’s nuclearisation and US foreign policy shifts under the second Trump administration have raised security concerns in South Korea. With rising scepticism about US security guarantees, domestic debates on South Korea’s nuclearisation and how it manages the North Korean security threat have intensified. Besides these issues, this article also examines the strategic dilemmas, the economic impact, diplomatic options, policy implications, and the future of US-South Korea-North Korea relations.
COMMENTARY
The Democratic People’s Republic of Korea (DPRK or North Korea) conducted its first nuclear test in 2006, followed by a series of missile tests. North Korea’s nuclearisation, missile tests, and nuclear threats against the Republic of Korea (ROK or South Korea) have been a grave security concern to East Asia.
The 1953 partition of the Korean Peninsula marked the beginning of a persistent rivalry between the two states, leaving them perpetually in a state of heightened tensions. While both governments have sought eventual reunification, their security concerns, trust deficits, and weak commitment towards conflict resolution have contributed to bilateral tensions and insecurity in the wider Indo-Pacific.
The United States has played a significant role in the geopolitics of the Korean Peninsula following the end of the Korean War through the 1953 US-ROK Mutual Defence Treaty, which guarantees the latter a place under the US security umbrella. The deployment of 29,000 US troops in South Korea aims to defend it and deter aggression from North Korea.
Under the Non-Proliferation Treaty (NPT), both North Korea and South Korea have since maintained the status of Non-Nuclear Weapons States, focusing on a normative approach of non-nuclearisation and prioritising economic growth. North Korea left the NPT in 2003 and went on to develop its nuclear and missile programme. Between 2017 and 2024, it conducted six nuclear tests and many missile tests of short, long, and intercontinental-range missiles, despite heavy sanctions from the West. Pyongyang’s relations with Tokyo have deteriorated as a result of its missile firing over Japan and its territorial waters, which were violations of international law.
The involvement of external powers like the US, China, Russia, and Japan in the Korean conflict has complicated conflict resolution efforts between the ROK and DPRK.
US Foreign Policy and the Trump Factor
Over the last few decades, the United States has made several attempts at denuclearising North Korea through various means, including the use of sanctions, sanction waivers, and diplomacy, such as the so-called Six-Party talks involving the ROK, DPRK, US, Japan, China and Russia. For instance, its negotiations with North Korea between 1999 and 2019 were aimed at getting the latter to agree to a nuclear moratorium, to abandon the pursuit of nuclear weapons, and to deter it from engaging in further nuclear activities.
Since 2009, the US has attempted to reengage in diplomatic negotiations with North Korea, including the Obama administration’s US-DPRK bilateral talks between January 2009 and January 2017 and the Six-Party talks. Apart from a brief suspension of North Korea’s nuclear programme, no significant success in denuclearisation was achieved.
During the first Trump administration, significant attempts were made between January 2017 and January 2021 to negotiate with North Korea’s President Kim Jong-Un. While President Trump became the first serving American president to step foot in North Korea in 2019, and the US-DPRK bilateral talks in Singapore (2018) and Vietnam (2019) led to agreements on lasting peace, no progress was achieved on the abandonment of Pyongyang’s nuclear ambitions.
From January 2021 to January 2025, the succeeding Biden administration promised North Korea complete relief from sanctions in return for complete denuclearisation, with no reciprocal commitment by the latter. The US signed a classified “nuclear guideline strategy” with South Korea, reaffirming its commitment to defend it in the event of a nuclear attack from North Korea. Under this strategy, US nuclear weapons would be deployed on the ground and around South Korea to respond to a potential nuclear attack by North Korea. This guideline strategy notwithstanding, the ROK is not confident that it will survive future changes of US administrations.
Thus, North Korea’s engagement with the US, involvement in the Six-Party talks and the ROK-DPRK dialogues have led to Pyongyang receiving measured sanctions relief from the US without it having to commit to denuclearisation. Moreover, its relentless nuclear and missile testing programmes have dented the probability of peace between the two Koreas and challenged US foreign policy and its strategic approach to the peninsula’s security crisis.
The re-election of Donald Trump has raised more concerns and insecurity in Seoul because of his unpredictability and looming questions over the reliability and continuity of the US security guarantee for the region. As a result, South Korea’s political leadership have been driven to reconsider its non-nuclear nation status and whether it should develop an independent nuclear capability as a deterrence against the North Korean nuclear threat.
Debates on the Nuclearisation of South Korea
Domestic opinion on whether South Korea should acquire nuclear weapons is divided. According to a 2022 survey by the Chicago Council on Global Affairs, there was overwhelming support for South Korea’s nuclearisation, with approximately seven out of ten South Koreans preferring the nation to develop its own nuclear weapons and about 67 per cent opting for an independent arsenal. On the other hand, 26 per cent opposed South Korea’s nuclearisation, and four in ten opposed the US deployment of nuclear weapons. Similar sentiment was demonstrated in the 2024 survey by the Korea Institute for National Unification where six in ten South Koreans favoured having nuclear weapons if DPRK does not denuclearise.
Rising domestic support for South Korea’s nuclearisation stems from the security threats posed by Pyongyang and Beijing, the ambiguity of US foreign policy, and its relative inaction in reaffirming the security guarantee for the Korean peninsula. North Korea’s frequent sabre rattling also created pressure in negotiations. Possessing nuclear weapons could provide the required leverage for South Korea at the negotiating table. Donald Trump’s re-election has accelerated these debates, increasing the view that nuclearisation is becoming more necessary than ever.
Those against South Korea’s nuclearisation doubt that North Korea would ever use its nuclear weapons, given the risk of self-destruction from the irradiation. They view its acquisition of the weapons as a means to ensure regime survival. They have also argued that it would damage the normative and ethical fabric underlying Seoul’s anti-nuclearisation policy and could drive a nuclear arms race, greatly diminishing the prospects for the peninsula’s denuclearisation or peaceful unification.
Furthermore, in leaving the NPT, South Korea could also face similar sanctions as North Korea from neighbouring countries and allies, undermining its domestic and regional economic growth. Thus, the denuclearisation of the Korean Peninsula is considered an issue to be resolved through dialogue and negotiations, alongside efforts to deter Pyongyang from conducting nuclear tests.
The Way Forward
Dialogue between Seoul and Washington is essential to finding common ground on Korean security and regional stability. It is not feasible for South Korea to start an independent nuclear programme while maintaining its military alliance with the US.
The US needs to build trust with South Korea by reaffirming its security guarantee and commitment to the Biden administration’s “nuclear guideline strategy”. It also needs to successfully negotiate with North Korea to abandon its nuclear threats, cease its missile programme, and engage in inter-Korean peace dialogue.
As an alternative to developing nuclear weapons, South Korea could work out a semi- or de facto nuclear-powered arrangement with the US to maintain deterrence capabilities without testing nuclear weapons. A model involving South Korea, the US and other regional allies similar to that of AUKUS could be an option. However, that could also stir insecurity among Seoul’s adversaries and strategic rivals.
South Korea has also sought a tariff waiver for its 2.5 million tonnes of steel exports to the US following the latter’s announcement of a 25 per cent tariff on steel and metal products on all countries. Attempting to develop a nuclear capability will also disrupt South Korea’s relations with export destinations such as China, Vietnam, Japan, Hong Kong, Taiwan, Singapore, India, Australia, Mexico, Germany and Malaysia. It could also cause damage to the electronics sector and supply chains in the Indo-Pacific, which would force the US to take a position to protect its supply chains from disruptions while preserving US and global economic interests.
Finally, the unification of the Korean Peninsula has been an ultimate objective for both South Korea and North Korea. However, the involvement of extra-regional actors has made the situation more complex and inconducive to conflict resolution. Therefore, the ROK-DPRK bilateral dialogue without third-party big power interference is crucial, while regional geopolitical actors like Japan, India, Australia and Indonesia can provide informal support.
About the Authors
Dr Astha Chadha is an Associate Professor at Ritsumeikan University in Kyoto, Japan, and the author of Faith and Politics in South Asia (Routledge: 2024). Nihar Kulkarni is a PhD researcher at the Faculty of Political Science and International Studies, University of Warsaw, Poland. Both specialise in geopolitics and security dynamics in the Indo-Pacific region.
