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A major reconfiguration of the Indo-Pacific security architecture is underway. Conventionally underpinned by multilateral frameworks such as the Association of Southeast Asian Nations (ASEAN) and its affiliated platforms, as well as bilateral alliances led by the United States, the regional security architecture is now being transformed by the China-US strategic rivalry, a recalibration of partnerships, and the rise of smaller issue-based coalitions.

While these trends have been unfolding since the late 2010s, their scale and significance have grown in recent years. As a result, long-standing assumptions about regional peace and stability are being reassessed and, in some cases, left behind altogether. At the heart of this transition is a growing dissatisfaction with traditional multilateralism and bilateralism among regional countries, which has become more pronounced under the second Donald Trump administration.

Much has already been written about the constraints of the ASEAN-led multilateral model, and it bears no need for repetition. Suffice it to say that ASEAN’s consensus-based, confidence-building, and inclusive approach has been regarded as falling short in addressing security challenges such as the South China Sea disputes or the ongoing crisis in Myanmar. This has prompted some regional countries to explore alternative formats of cooperation that better align with their interests.

Although the second Trump administration has yet to articulate a clear stance on ASEAN, its general disinterest in multilateralism—coupled with the first Trump administration’s limited engagement with ASEAN—indicates that Washington would be unlikely to see much value in the Southeast Asian grouping, at least for the next four years.

The US-led hub-and-spokes alliance system in the region has also experienced notable strain since the late 2010s. While the recent trips to Japan and the Philippines by US Defense Secretary Pete Hegseth may have helped ease anxieties regarding Washington’s commitment to its regional allies, it is likely that President Trump’s previous criticisms of Japan and South Korea for free-riding on US security guarantees will continue to loom large.

Fortuitously, perhaps, this has led to more sustained efforts to strengthen spoke-to-spoke linkages. In June 2024, for instance, an inaugural Australia-Japan-Korea Track 1.5 dialogue was convened in Sydney. Since 2022, Japan has also forged bilateral reciprocal access agreements with Australia, the United Kingdom, and the Philippines, which would facilitate closer military exchanges.

These developments portend the emergence of what might be characterised as a “modular” and decentralised security architecture—one in which states prioritise overlapping coalitions based on specific interests and threats, rather than committing to rigid alliances or overarching blueprints. Certainly, this coexistence of multilateralism, bilateralism and so-called minilateralism is not new. What sets the current moment apart, however, is the pace at which this reconfigured security architecture is taking shape.

Such an architecture is arguably more unstable—given the absence of formal institutionalisation—but is also more flexible and adaptive to shifting needs and realities. Cooperation would be more visibly grounded in shared interests and mutual commitment, with the recognition that these interests and commitments may evolve over time.

A modular security architecture encourages and fosters diversification in partnerships, allowing states to selectively engage with the groupings that best align with their interests on specific issues. This could also help to boost the agency of smaller and medium-sized countries, presenting them with more options to influence outcomes. Moreover, these countries could initiate issue-based coalitions without having to invest resources in institutionalising a large multilateral forum.

Undoubtedly, this transition also comes with challenges. For one, the region faces a higher risk of polarisation and fragmentation if the issue-based coalitions persistently align with one side or the other amidst escalating great power rivalry. Some countries may also be consistently sidelined in the formation of such coalitions, which not only leaves them with fewer avenues to voice their concerns but also points to a more exclusionary architecture overall.

To address these potential challenges and leverage the benefits of this evolving security architecture, regional actors should explore how the various forms of cooperation—both existing and new—can be complementary and collectively enhance the region’s overall stability. This moment of flux offers an opportunity for regional countries to (re)design a security architecture that more effectively advances their individual and shared interests.

The Indo-Pacific security architecture is transforming into a modular and decentralised system where bilateralism, multilateralism and minilateralism coexist in complex and sometimes contradictory ways. The imperative is for regional countries to build a more resilient and responsive architecture—one capable of addressing both traditional and emerging concerns while preserving the stability of the Indo-Pacific.

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Image: An Australia-Japan-Republic of Korea 1.5 Track Dialogue hosted in Sydney, Australia in June 2024 (United States Studies Centre).

This article was published in The Korea Times on 30 April 2025. You can find the original article here.