Vol. VII / No. 14 | September 2026
Authors:
Rangga Aria Wijaya-Undergraduate Student, Department of International Relations, Universitas Indonesia
Summary
Since 1995, ASEAN has already had its own nuclear-weapon-free zone, named the SEANWFZ (Southeast Asia Nuclear Weapon Free Zone). Yet, the protocol that was supposed to bind the nuclear-weapon states was left in a deadlock. The concern surrounding the geographical coverage and the scope of the negative security assurance (NSA) has been the main reason for this prolonged delay. Three decades later, ASEAN remains committed in pursuing the protocol. This commentary then questions the relevance of the protocol for ASEAN. It finds that the protocol still matters for two reasons. First, the original mandate of SEANWFZ also includes managing external threats, and failure in one dimension will degrade the institution as a whole. Second, external threats are still looming and even growing, with the existence of AUKUS. But relevance is not the overall reason why ASEAN is still pursuing the protocol. The contemporary geopolitical situation, such as China’s nuclear policy and AUKUS, that provides the impetus for ASEAN to sustain the momentum toward it.
Introduction
The Southeast Asian Nuclear-Weapon-Free Zone (SEANWFZ) was established in 1995 to prevent any of the ASEAN member states from owning nuclear weapons that were proliferating post the Cold War. The more important issue at that time was also to legally bind the five nuclear weapon states (NWS), which are the United States, Russia, the United Kingdom, France, and China. Therefore, SEANWFZ was also accompanied by an additional protocol. The plan was for the five NWS to sign the protocol, which would prohibit them from using or threatening to use nuclear weapons within the zone, and also give ASEAN the NSA.
However, SEANWFZ remains the only nuclear-weapon-free zone (NWFZ) that does not have a single signature from the NWS. The two main concerns from NWS are (1) the expansive geographical coverage and (2) the extensive scope of the NSA. SEANWFZ has wider geographical coverage compared to the other NWFZs, which include the exclusive economic zones and continental shelves of its state parties. The NSA requested by SEANWFZ also uses the words “within the zone.” This means that not only can the NWS not use them against the zone’s states, but they also cannot use them against any states from inside the zone. A series of negotiations and consultations to solve these issues have been done for years with no significant outcome. This has resulted in a deadlock that’s been going on for three decades. Until recently, SEANWFZ showed signs of life, as in July 2025 ASEAN finally accommodated China by letting it be the first to sign the protocol. Not long after, in May 2026, the 48th ASEAN Summit also reaffirmed ASEAN’s commitment to keep pursuing the realisation of the protocol.
This decision has raised a question that will be the main discussion in this commentary: why is ASEAN still trying to pursue the SEANWFZ Protocol despite its three decades of deadlock? As for the ongoing delay, doubting its relevance is to be expected, especially since ASEAN is doing just fine without it—or at least that’s how it seems at first glance. For that purpose, this commentary will reassess the relevance of the SEANWFZ Protocol to understand why it still matters for ASEAN, particularly by considering recent developments in the region.
Institutional Balancing: The Fundamental Purpose of SEANWFZ
In reassessing its relevance, understanding the institution’s original purpose is a necessary step. There are, of course, many perspectives that could explain why. But this commentary borrows an argument from Kai He’s (2007) paper, which explains that states use institutions as a balance-of-power instrument, known as institutional balancing. He notes that states will use institutions to balance internal challenges as well as external threats. Therefore, based on this theory, the relevance of an institution will be seen in how it serves both of these for member states.
For Southeast Asia, the internal challenge back during the Cold War was the fear of nuclear proliferation that could spread inside the region, whether self-owned or deployed by the NWS. But only by the end of the Cold War did ASEAN manage to create an institution specific to tackle this concern. Thus, the SEANWFZ Treaty itself was the internal balancing instrument, as it contains the binding agreement that no ASEAN members could possess nuclear weapons. But an external balancing instrument was also needed, as an external threat has also existed since the Cold War, which is the NWS itself. Therefore, that’s what the additional protocol was for.
Kai He also emphasizes that both dimensions work mutually influencing, which means weakness in one dimension will affect the other. While SEANWFZ seems to be going well in managing internal challenges, the other was not so much. The dangerous thing is that the commitment of ASEAN countries not to acquire nuclear weapons was supposed to be complemented with guarantees from the NWS through the NSA. Failure to secure this will undermine ASEAN’s commitment to the treaty, which threatens the existence of SEANWFZ itself. Eventually, pursuing the protocol every year became a mandatory routine, as complete abandonment will invite nuclear proliferation among its members.
SEANWFZ in a New Era: The Problem with AUKUS
Almost three decades later, the external threat that the SEANWFZ Protocol meant to balance still exists, or in fact is growing, considering recent developments in the region. A particularly contentious moment came in 2021, when the United States (US), the United Kingdom (UK), and Australia announced their new regional alliance in the Indo-Pacific, called AUKUS. Its main programme, as well as ASEAN’s biggest concern, was the three-phase building of Australia’s nuclear-powered submarine capabilities. This means that the US and UK, which strain SEANWFZ by not signing its protocol, are now sharing their nuclear technology with a non-nuclear-weapon state that shares a border with Southeast Asia.
ASEAN members’ response towards this AUKUS plan remains “nuanced,” with Indonesia and Malaysia being the most vocal in expressing the region’s concern. Their concerns are mainly focused on the nuclear proliferation issue, which came from the fact that nuclear-powered submarine reactors have near—if not reaching—weapon-grade uranium enrichment levels. While it is true that Australia has shown its commitment to the non-proliferation regime, ASEAN is concerned that this programme model, if left unchecked, could be followed by other countries as a way to achieve a covert nuclear weapons programme.
However, there was a noticeable “change in tone” with Indonesia and Malaysia’s statements in 2023 that could be said to be more “accommodating.” Some suggest that ASEAN’s stance was tamped down thanks to AUKUS diplomacy, especially Australia’s. This commentary, however, begs to differ. ASEAN does not seem to back down from its original stance. AUKUS diplomacy just shows ASEAN that they are uncompromising about this, leading ASEAN to choose a different strategy rather than going head-to-head with one of the most powerful alliances. This strategic shift was seen in July 2025, with ASEAN—led by Malaysia—finally welcomed China to sign the SEANWFZ Protocol individually.
ASEAN Strategic Shift towards China
Prior to China’s meeting with Malaysia in January 2025, ASEAN decided to finally explore the possibility of allowing NWS to sign and ratify the protocol individually. Before this, ASEAN always had a “package deal” policy, where all NWS disputes were to be resolved collectively, and the accession was to be done simultaneously. This policy has always been the one issue that prevents SEANWFZ from achieving any single NWS signature. For example, SEANWFZ almost achieved China’s signature in 2012, had it not been for ASEAN’s decision to delay until the other NWS reached an agreement.
China’s support for SEANWFZ can already be traced back to 1999, with only one reservation, that single concern was the South China Sea, as China feared that the protocol would undermine its interests in the disputed territory. The deal in 2012 was supposed to resolve this, with ASEAN and China having agreed to sign a Memorandum of Understanding (MoU) prior to signing the protocol. This willingness to pursue SEANWFZ was part of China’s dual-track approach in nuclear policy. With this approach, China manages to project itself as a leader in supporting the non-proliferation regime, while still expanding its nuclear arsenal.
Meanwhile, for SEANWFZ, China’s approach is an opportunity. With AUKUS still lurking as a threat, inviting its main challenger inside is similar to calling in reinforcements. China’s participation could create a ripple effect that will confront AUKUS. First, it could accelerate Russia’s accession, which will pressure the remaining NWS, including the US and UK, to also sign. Second, China could amplify ASEAN’s voice in delegitimizing any nuclear presence, especially the nuclear-powered submarine, within the zone. In the end, China’s policy provided the political window to realise SEANWFZ’s protocol.
Does the SEANWFZ Protocol Still Matter?
Going back to the question, theoretically, yes, because the original mandate of SEANWFZ also includes managing external threats, as failure in one dimension will degrade the whole institution itself. Empirically, also yes, because the external threats are still looming, and even growing with the existence of AUKUS. But relevance is not the overall reason why ASEAN is still pursuing the protocol. With China’s consistency, ASEAN does it because it still sees a possibility of realising it one day. The urgency generated by AUKUS has recently compelled ASEAN to accelerate its engagement with the opportunities presented by China.