№ 9, 2024. Revitalizing the Southeast Asian Nuclear Weapon-Free Zone in the Era of Great Power Rivalry

Graduate student at Georgetown University
May 20, 2024

Signed in 1995 and entering into force two years later, the Southeast Asian Nuclear Weapon-Free Zone (SEANWFZ) is a treaty between the 10 Southeast Asian member-states of the Association of Southeast Asian Nations (ASEAN): Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Singapore, Thailand, and Vietnam. Parties to the treaty are obligated not to develop, manufacture, acquire, possess, or control nuclear weapons within the zone. The protocols of the treaty remain open for signature by the nuclear weapon states (NWS), which none have signed. Doing so would mean that the NWS would forgo the threat or use of nuclear weapons against any state party to the treaty[1]. Given the strategic importance of Southeast Asia, especially to the United States of America and the People’s Republic of China, alongside the unresolved maritime disputes between Beijing and Southeast Asian capitals, taking up such a pledge would limit their strategic options in furthering their national interests.

Unlike assessing bilateral arms control agreements between the US and Russia, the concept of “strategic stability” between non-nuclear weapons states (NNWS) and NWS adopts a different character. Suppose the traditional definition of strategic stability is the absence of incentives for any country to launch a first strike. In that case, the NNWS of Southeast Asia lack any corresponding nuclear means to deter an NWS from the threat or use of nuclear weapons in the region. Therefore, the conceptual framework we must adopt when analyzing SEANWFZ is to visualize two concentric and equidistant circles where the inner circle is SEANWFZ and the negative security assurances it seeks to attain in the interests of regional stability, and the outer circle that is strategic stability between the NWS, particularly between the US and China, in our case. A change in one circle will affect the other; both must remain equidistant to maintain stability. As the founding Prime Minister of Singapore, Lee Kuan Yew, paraphrasing an African proverb, remarked, “When elephants fight, it is the grass that suffers. When elephants make love, the grass suffers, too.[2]” There is no tranquility in the walled garden if the world beyond is on fire.

Conflict between China and the US would mean that those caught in-between would either have to pick sides, be trampled upon, or both. On the other hand, if Beijing and Washington overcome their differences and become inseparable allies, then the balance of power in Southeast Asia would be dangerously tilted to one side in favor of the great powers. If the outer circle expands, so must the inner circle, and vice versa. Through this conceptual framework, this paper will attempt to apply the strategic implications of SEANWFZ.

Part I: The Net-Negative Implications of SEANWFZ on Regional and Strategic Stability

Protocols Remain Unsigned

For signatories of SEANWFZ to achieve their desired political outcome, the five NWS must sign the protocol to the treaty. In doing so, the NWS would agree not to violate the terms of the treaty, forgoing the threat or use of nuclear weapons. The net-negative implications on regional and strategic stability of this desired outcome are manifold. Firstly, almost three decades after the treaty went into effect, the fact that the NWS have yet to sign the protocols demonstrates their lack of willingness to give ascent to the collective interest of the ASEAN member states. The longer the zone’s protocols remain unsigned, the clearer it may become that the treaty is no more valuable than the paper on which it is written. If, for example, China decides to escalate a crisis in the South China Sea and becomes confident to signal its nuclear deterrent to Vietnam or the Philippines, then the treaty will burn before the region does.

Applying this to the framework of the two concentric circles, the treaty itself may serve as a positive development for regional stability as the ASEAN states demonstrate their ability to reach a consensus reconciling their national security interests. On the surface, ASEAN can put up a united front in its position on nuclear issues with the treaty as a reference point. However, the evident strategic instability of the Sino-American rivalry shrinks the outer circle, which could essentially cave in on the inner circle. Even if the treaty stabilizes the region, great power strategic instability subtracts more from the equation, whose sum would be a net-negative.

Incentives for Conventional Conflict and Arms Racing

Detractors of complete nuclear disarmament raise an important but valid point: the complete elimination of nuclear weapons would revive the specter of large-scale conventional warfare. In the perfect world where the NWS disarms and NWFZs are reinforced, what will deter belligerent states from utilizing violence as a means to resolve international disputes? Would China be deterred from consolidating islands in the South China Sea and potentially Taiwan without Washington’s nuclear deterrence? More particularly in inter-ASEAN relations, without the potential intervention of NWS, the cost to engage in conflict is decreased without the potential credible intervention of a great power.

The net-negative implications of the Zone, if it is able to achieve its “ideal-type” outcome in an environment of a “world free of nuclear weapons,” would remove a factor that keeps leaders in the “bottom branch” of the strategic stability model and additionally encourage conventional arms racing to enhance their national defense capabilities. The region, and arguably the rest of the world, would be trapped in an endless security dilemma reminiscent of Europe leading up to the Great War.

A Product of Compromise

ASEAN prides itself as a regional organization for following the “ASEAN Way,” that is, a practice of reinforcing normative values towards cooperation, compromise, and consensus[3]. SEANWFZ was a product of this process, which reveals differences within ASEAN. The Philippines, Thailand, and Singapore depended on US military presence to enhance their national defense; the former two have bilateral defense treaties with Washington, and the latter hosts a US naval facility[4][5]. These positions stood in contrast to Malaysia and Indonesia, which wanted SEANWFZ to restrict foreign military assets from passing through the region. This was a point of contention as the Philippines, Thailand, and Singapore depended on the ability of a non-regional power to navigate through the region and come to their defense in the event of a conflict. For this reason, these member states lobbied for Article 7 of the treaty, which stipulates that member states“ may decide for itself whether to allow visits by foreign ships and aircraft to its ports and airfields, transit of its airspace by foreign aircraft, and navigation by foreign ships through its territorial sea… in a manner not governed by the rights of innocent passage, archipelagic sea lanes passage or transit passage[6].”

The effects of this article are not necessarily felt when there is stability in the region, as the welcoming and hosting of foreign military assets would not be viewed as a threat by another. But, if the inner circle of regional stability shrinks, then it invites an increased role of great powers into the region in an attempt to either restore balance or achieve gains. Hypothetically, in a crisis instability situation where either Indonesia or Malaysia (or both) threatens the use of force to resolve a dispute with Singapore, and Washington signals its support for the city-state by deploying its 7th Fleet, this would be viewed by Jakarta and Kuala-Lumpur as threatening and potentially inviting Beijing into the crisis. Yet all parties trapped in this escalatory spiral can refer to Article 7 of SEANWFZ and claim what they are doing is within their prerogative. Fears of smaller states towards larger states in Southeast Asia are not unfounded. Brunei, in 1962, staged a revolt in a successful attempt to resist joining the Federation of Malaysia[7]. Singapore experienced an intense insurgency campaign led by Indonesia known as Konfrontasi between 1963 and 1966[8]. Fears were also revived in 1991 when Malaysia and Indonesia staged a joint military exercise just 20 kilometers from Singapore during its national day on August 9[9]. The formation and reinforcement of ASEAN were motivated to create a region of coexistence, but a norms-based project remains strong as long as the norms continue to exist. The politics of compromise and consensus produces a single result that all parties can agree towards. If the environment changes, however, that single result can become subject to independent reinterpretation and then disagreement.

The Net-Positive Implications of SEANWFZ on Regional and Strategic Stability

Norm Establishment and Institutionalization within ASEAN

Although the previous section highlighted particular issues in SEANWFZ, the treaty remains a significant milestone not just for ASEAN but towards the aspirational goal of a world free of nuclear weapons. As a whole, the treaty makes that first step and establishes the norm of non-proliferation and a rejection of the threat and use of nuclear weapons in the region. In the event of a breach of these norms, the ASEAN states, or any intervening country, can refer to SEANWFZ as “name, shame, and blame,” with the hopes of disincentivizing destabilizing actions with SEANWFZ as a vital instrument when appealing to international organizations like the United Nations. On a regional level, the treaty strengthens the inner circle of the two-concentric circle’s concept with the hopes of avoiding a situation where “the center cannot hold,” and great powers are drawn into the region as they were, most notably during the Vietnam and Cambodian Wars.

Article 8 of the treaty establishes a Commission for the zone, which consists of the foreign ministers of the state parties. The foreign ministers are to meet regularly to oversee the implementation and compliance of the treaty. An “Executive Committee” is also established as a subsidiary organ of the Commission to ensure the operation of verification measures, conduct fact-finding missions, and carry out tasks assigned by the Commission. The institutionalization of SEANWFZ allows the treaty to operate alongside and semi-independently, which provides a space where substantive issues can be resolved constructively. This is a net-positive for regional stability, for it also allows ASEAN to develop a track record of its non-proliferation efforts, demonstrating to the rest of the world its dedication to the peaceful use of the atom. In terms of its implications on strategic stability, such norms help reassure the nuclear powers that regional states do not seek to match the former’s deterrent capabilities. If Vietnam, for example, chooses the path towards proliferation, then China would be more inclined to escalate its actions in the South China Sea, which would inch closer to a “use or lose” situation.

IAEA Safeguards for Peaceful Use

One measure SEANWFZ offers to further embed the norm of non-proliferation in the region is stated in Article 5 of the treaty. Each state party must conclude an agreement with the  International Atomic Energy Agency (IAEA) for the application of full-scope safeguards for peaceful nuclear activities. Involving the IAEA contributes to further reassurance that proper measures are in place in compliance with international norms and practices on non-proliferation and ensuring that a neutral international organization can certify that. This complements trustbuilding and cooperation within ASEAN as member states are to follow not just the treaty stipulations but also the best practices set by an independent agency. The same positive reassurances are offered to the great powers vis-a-vis the region. In the event that a Southeast  Asian state does decide to pursue nuclear proliferation, then safeguards are in place to ensure that such a project can be detected and stopped early.

Opportunity for Great Powers to Demonstrate Restraint

What the state parties of SEANWFZ hope for is that the NWS sign the protocols of the treaty, thereby ensuring that they adhere to its requirements, principles, and norms. At its core, this would mean providing negative security assurances and enforcing this by demonstrating nuclear and conventional restraint. The treaty, as a whole, highlights Southeast Asia’s general aspirations and collective opinion on nuclear weapons. China and the US are invaluable partners in the region; both not only have to demonstrate their military capabilities but also to win the “hearts and minds” of the Southeast Asian peoples as responsible great powers. In 2022, China and the US accounted for 19% and 11% of ASEAN’s total global trade, respectively[10]. The region prioritizes economic cooperation, growth, and prosperity with a cautionary attitude to military escalation and getting entangled in a US-China conflict. Washington, especially, wants the confidence that its partners, whether in Southeast Asia or any other part of the world, are “on its side.” This has especially been the case with the Biden administration’s framing of a “democracy versus autocracy” confrontation[11]. How do such statements reassure nations like China, who passionately call for the abandonment of “Cold War thinking”? This is where SEANWFZ provides an arena where China and the US can display their leadership capabilities not through coercion but through acting as “good neighbors” in a region where binaries give way to various shades of grey, and the threads of the US-China relationship are far more intertwined.

Part II: Opportunities and Methods to the Revitalization of SEANWFZ

The preceding section analyzed SEANWFZ through the strategic stability model and, when it does apply, how aspects of the treaty contribute to stability within Southeast Asia and between the great powers. This analytical exercise elicited important points: First, if the protocols remain unsigned by the NWS, then the treaty fails to achieve its ideal outcome. Second, if the parties to SEANWFZ do manage to attain the signatures of the NWS, then a stable nuclear situation may generate the incentives for conventional conflict and arms racing. Third, as a product of compromise, a possible renegotiation of SEANWFZ would reveal further divisions not just between the NWS but the ASEAN member states. Fourth, as a general initiative, SEANWFZ provides an opportunity for the NWS to demonstrate their behavior as responsible nuclear powers, but this choice is left to the NWS alone. It seems partially reasonable, then, to make the case that the strengths of SEANWFZ are also potential weaknesses. Yet, the absence of such a treaty would have been far more destabilizing; for instance, there were suspicions that Myanmar’s military government was involved in a “secret nuclear network”[12]. Had SEANWFZ not been ratified and norms of non-proliferation within the region not created, Southeast Asia might have taken a completely different path. SEANWFZ is an important document and has demonstrated its positive utility; however, 27 years have passed since it came into force, and the geopolitical landscape of the late 20th century is drastically different to where we are today. As Beijing and Washington look at each other with suspicion and tensions having the potential to worsen, can SEANWFZ be revitalized to reshape the geopolitical equation in Southeast Asia?

At the 2023 ASEAN Foreign Ministers meeting in Jakarta, Indonesia’s Foreign Minister Retno Marsudi urged the NWS to join SEANWFZ, warning that Southeast Asia is “one miscalculation away from apocalypse”[13]. She highlighted that underlying the nuclear threat are the existing crises in ASEAN, from the civil war in Myanmar to China’s territorial claims in the South China Sea. All these factors create an environment for potential miscalculation, and this has to be managed not just by the regional states but also by the great powers that have significant influence in the region. Returning to the two concentric circles of regional and great power strategic stability, efforts must be made to strengthen both but in a manner that does not incur a cost at the expense of the other. For this reason, the primary option that might be most suitable in the case of SEANWFZ is to depend on existing multilateral forums to continue the conversation.

APEC as a Platform for Further Discussion

Established in 1989, the Asia-Pacific Economic Cooperation (APEC) forum consists of 21 member economies in the Pacific Rim with the goal of promoting free trade. The forum meets annually, with chairmanships rotating among its members. What is significant about APEC is that it brings together the permanent members of the United Nations Security Council (P5) and includes Taiwan (Chinese Taipei) in the meetings. Although APEC may be primarily focused on economic issues, discussing strategic stability or “mutual vulnerability” issues should not be excluded. At its core, the US-China relationship is based upon the economic interdependence of the two powers. Within this economic web, the ASEAN states are caught in between. The agenda at certain APEC meetings could be an opportunity for members to raise the issue of how geopolitical tensions and saber-rattling are fundamentally bad for business. Member states dependent on both the US and China can press for greater clarity on the future of the two nations’ relationship and the call to demonstrate restraint in times of crisis. This option allows everyone to “maintain the subject, but change the venue,” hopefully generating a better picture for US and Chinese policymakers. Furthermore, ASEAN members can act as a bloc to link security and economic interests, stressing that common economic prosperity depends on stability between member states. By signing the protocols of SEANWFZ, the NWS can demonstrate their appreciation for this fact, reframing it as a necessity for economic cooperation.

Inter-NWFZ Consultations

Other NWFZs have demonstrated success in securing P5 signatures to their respective protocols. China, France, Russia, and the United Kingdom have signed and ratified the protocols to the Treaty of Rarotonga (South Pacific NWFZ). The US has signed but not ratified the protocols. The P5 have also signed and ratified the protocols of the Treaty of Tlatelolco (Latin America and the Caribbean NWFZ). In Central Asia, all the P5 states except the US have ratified the protocols to the Central Asian Nuclear Weapon Free Zone (CANWFZ), which went into effect in 2009. This is also the case with the African Nuclear-Weapon-Free Zone, where all the P5 states except the US have ratified its protocols. It is worth highlighting that the success of the Treaty of Tlatelolco was certainly aided by the political will that existed after the Cuban Missile Crisis. It would be reckless to argue that other regions should undergo such a crisis in order to secure their NWFZ aspirations. The varied progress of the NWFZs of the world demonstrates different phases that are possible given the political circumstances of the day. With different experiences and expertise in regional institutionalization of the treaties, the NWFZs may benefit by coordinating with each other and collectively lobbying for complete P5 ratification of their protocols. This would also further consolidate the interests of states with similar aspirations and allow them to work together as a voting bloc in multilateral organizations when discussing nuclear issues.

One area of substance where an inter-NWFZ consultative body may involve the P5 could be dealing with the illicit trade of nuclear material and technology. The zones cover areas where transnational crime and terrorism remain pertinent issues. It would not be in the interests of any nation-state for a non-state actor to acquire a nuclear weapon. To combat this destabilizing outcome, the P5 and members of the NWFZs can find common ground by furthering cooperation in tackling transnational crime, especially focusing on the illicit trade of nuclear material. With the NWFZ treaties already involving the IAEA, the inter-NWFZ consultative body may also include the International Criminal Police Organization (INTERPOL) and anti-terrorism agencies of the respective P5 states to consider areas of cooperation. As an initial dividend, the P5 states might be convinced that the NWFZs can play a positive role in global nuclear stability instead of solely wanting negative security assurances.

Possibility of Amending SEANWFZ?

One consideration parties to SEANWFZ could take into account is the possibility of amending SEANWFZ or its protocols as a compromise with the P5 states. Prior to SEANWFZ coming into force, the nuclear powers had already expressed their reservations on various aspects of the treaty. The US raised concerns that the inclusion of maritime Exclusive Economic Zones (EEZs) was inconsistent with international law and that Article 7, pertaining to “innocent passage” of naval vessels, left too much to interpretation. Naturally, China was concerned that the territorial coverage of the treaty included disputed islands in the South China Sea and that signing the protocols of the treaty would affect its claim to the Spratlys. In 1996, Russia expressed its acceptance of the treaty but sought further clarification on how it would be implemented.[14] The current global situation has changed, and the danger of amending SEANWFZ might open a can of worms that would turn an effort for cooperation into conflict. If the ASEAN states manage to clarify and amend parts of the treaty that the US may be amenable towards, China and Russia may act as spoilers moving forward. Neither would the ASEAN states wish to alienate China, especially. However, parties to SEANWFZ should consider avenues for revitalization and engage on a “mini-lateral” level through the preexisting ASEAN+ platform to discuss their wishes regarding the treaty separately with Beijing and Washington. In 2021, President Xi Jinping expressed his interest in signing the protocols of the treaty; this came shortly after AUKUS was announced. To mitigate the risks of escalation and misunderstanding, ASEAN can utilize SEANWFZ in an indirect manner to consider both Beijing’s and Washington’s security concerns in the process of amending SEANWFZ. The ASEAN-facilitated process itself could serve as a stabilizing force in US-China relations to get a conversation started. This would alleviate the burden of either Beijing or Washington to be the first to initiate the discussion, leaving the responsibility to ASEAN alone.

Leveraging US Strategic-Military Partnerships

Unlike the transatlantic alliance system, the US presence in Asia is bound by a complex “hubs and spokes” system, as described by Dr. Victor Cha[15]. While this has presented complications in creating a collective means to deter what Washington and its allies perceive as Chinese aggression, it has also given Washington the ability to tailor its alliance system on a bilateral basis. Both a US treaty ally and party to SEANWFZ, the Philippines can leverage this role to clarify how US deterrence strategy in the region may involve nuclear weapons, and whether both Manila and Washington can deter China’s behavior in the South China Sea through more enhanced means. This is less of a concrete proposal but more of introducing the idea that ASEAN members are not helpless in revitalizing SEANWFZ if it wants to. Singapore also hosts US naval facilities and is a steadfast regional strategic partner for Washington. As the only other Chinese majority state outside “Greater China,” Singapore can additionally play a special role in helping Washington refine its optics on assessing China’s outlook of the world and acting as a conduit for US-China dialogue if necessary. These acts alone may help stabilize great power competition, thus indirectly serving the goals of SEANWFZ.

Wait, hope for the best, and seize the moment

As argued earlier, many of the NWFZs were products of the time they emerged. The Treaty of Tlatelolco made strides in securing P5 signatures and reinforcing its norms in the aftermath of the Cuban Missile Crisis. SEANWFZ went into force in 1997 when the Cold War became recent history. Mindful of this, the other option SEANWFZ could adopt is a “wait and see” approach. It can further its agenda in either two scenarios: In the event of a crisis or when great power competition subsides. In a time of regional crisis, ASEAN states can enforce the norms set out by the treaty, highlighting to the great powers and the world the importance of non-use and nuclear risk management. If Beijing and Washington had found a reason for cooperation, ASEAN could have seized on that moment and had China and the US sign the protocols to demonstrate a new era in US-China relations.


Realists may view NWFZs as utopian, arguing that its members are naive to hope and trust the nuclear powers to act responsibly. While valid as criticism, the mechanisms outlined in NWFZs and SEANWFZ, in particular, establish institutions and norms that would not have otherwise existed. Great power confrontation and conflict must be managed responsibly. This is incumbent not only upon the great powers to demonstrate restraint but also for the states caught in between to play a more active role in fostering dialogue, raising their concerns, and refocusing resources where constructive. The suggestions mentioned in this paper are not exhaustive, and other, more thorough ideas may yet have to be considered. Great power stability and regional stability are inseparable; our analysis of SEANWFZ has underlined this fact. Ideally, both must somehow find an equilibrium, and peace may be achieved from there. “He who submits to a state smaller than his own delights in Heaven,” wrote Mencius, the Chinese Confucian philosopher, “He who submits to a state bigger than his own is in awe of Heaven. He who delights in Heaven will continue to enjoy the possession of the Kingdom”[16].

[1] Treaty on The Southeast Asia Nuclear Weapon-Free Zone // ASEAN, 1995. URL: https://agreement.asean.org/media/download/20131230234315.pdf

[2] Vadaketh, Sudhir. The Problems with Teo Chee Hean’s MC on Oxley // Musings from Singapore, March 6, 2023. URL: https://sudhirtv.com/2023/03/06/the-problems-with-teo-chee-heans-mc-on-oxley/

[3] Caballero-Anthony, Mely. The ASEAN way and the changing security environment: navigating challenges to informality and centrality // International Politics, 2022

[4] Acharya, Amitav, J. D. Kenneth Boutin. The Southeast Asia Nuclear Weapon-Free Zone Treaty // Security Dialogue. 1998. Vol. 29, No. 2. URL: http://www.jstor.org/stable/44472123

[5] Bureau of East Asian and Pacific Affairs. U.S. Relations With Thailand // U.S. Department of State, May 4, 2021. URL: https://www.state.gov/u-s-relations-with-thailand/

[6] SEANWFZ, Article 7

[7] A Brief History of The Brunei Revolt And The Indonesian Confrontation // Imperial War Museum. URL: https://www.iwm.org.uk/history/a-brief-history-of-the-brunei-revolt-and-the-indonesian-confrontation

[8] Leong, Adam Kok Wey. How ‘Konfrontasi’ Reshaped Southeast Asian Regional Politics // The Diplomat, September 16, 2021. URL: https://thediplomat.com/2021/09/how-konfrontasi-reshaped-southeast-asian-regional-politics/

[9] Huxley, Tim. Review of Pukul Habis: Total Wipeout: A Story of War in Malaysia and Singapore, by David Boey // Contemporary Southeast Asia: A Journal of International and Strategic Affairs. 2023. Vol. 45, No. 2

[10] Wester, Shay. Balancing Act: Assessing China’s Growing Economic Influence in ASEAN // Asia Society, November 8, 2023. URL: https://asiasociety.org/policy-institute/balancing-act-assessing-chinas-growing-economic-influence-asean

[11] Biden, Joseph R. Remarks by President Biden on the United Efforts of the Free World to Support the People of Ukraine // The White House, March 26, 2022. URL: https://www.whitehouse.gov/briefing-room/speeches-remarks/2022/03/26/remarks-by-president-biden-on-the-united-efforts-of-the-free-world-to-support-the-people-of-ukraine/

[12] Crail, Peter. Report Alleges Secret Myanmar Nuclear Work // Arms Control Association, July, 2010. URL: https://www.armscontrol.org/act/2010_07/MyanmarReport

[13] Tarigan, Edna, Niniek Karmini. Indonesia Warns Nuclear Weapons Put Southeast Asia a ‘Miscalculation Away’ From Disaster // The Diplomat, July 12, 2023. URL: https://thediplomat.com/2023/07/indonesia-warns-nuclear-weapons-put-southeast-asia-a-miscalculation-away-from-disaster/

[14] Acharaya, pp. 225

[15] Cha, Victor. Powerplay: Origins of the U.S. Alliance System in Asia // Quarterly Journal: International Security. 2009. vol. 34. no. 3. URL: https://www.belfercenter.org/publication/powerplay-origins-us-alliance-system-asia

[16] Kim, Sungmoon. Mencius On International Relations And The Morality Of War: From The Perspective Of Confucian ‘Moralpolitik’ // History of Political Thought. 2010. Vol. 31, No. 1. URL: http://www.jstor.org/stable/26224087

Key words: ASEAN, International Security, Nuclear Non-Proliferation


F4/SOR – 24/05/20