Kurniawan Arif Maspul – Timor-Leste's accession to ASEAN this week came with a boom: not just a new flag at the summit in Kuala Lumpur, but a live demonstration of how great-power politics, resource competition and institutional fragility are colliding in Southeast Asia.
The bloc's first enlargement in more than 25 years is a momentous development for a country of roughly $2 billion GDP – and a stress test for an organisation that prizes consensus even as pressure from Beijing and Washington intensifies.
What made Kuala Lumpur distinct was the theatre around the accession. U.S. President Donald Trump used the summit to broker a high-profile ceasefire between Thailand and Cambodia and to press a transactional agenda of trade, minerals and defence deals – signalling Washington's willingness to convert visibility into influence, but doing so in a personalised, headline-driven mode that cuts both ways. Such spectacle reassures partners that the United States can still deliver leverage; it also revives doubts about long-term predictability when diplomacy is highly personalised.
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Two strategic novelties deserve rapid attention. Primarily, Timor-Leste's membership reshapes ASEAN's strategic geography. Located at the edge of the Indonesian archipelago and proximal to vital sea lines, Timor-Leste brings a history of fragile state-building and a foreign policy that has simultaneously courted Beijing and maintained ties with Australia and the West. Its accession therefore gives ASEAN a new, small-state voice that can press rules-based norms – especially given Timor-Leste's insistence on international-law principles in maritime disputes with Australia. That combination of moral authority and strategic location could make Timor-Leste an unexpected mediator in regional disputes – if, and only if, ASEAN helps it build capacity rather than leaving it exposed.
Conversely, the summit clarified how materially entwined competition has become. China's dominant hold over rare earth elements (REEs) and refining – estimates show Beijing accounts for roughly 69% of REE mining and an even larger share of processing and magnet production – gives it an asymmetric tool that underwrites both commercial leverage and strategic deterrence. In practical terms, control over REEs and the capacity to process them is an economic straitjacket for rivals whose green-energy and defence industries rely on these inputs. That economic leverage increasingly operates in tandem with maritime assertiveness in the South China Sea, where China's salami-slicing and refusal to accept the 2016 arbitral ruling create a constant low-grade risk of escalation.
Those two realities produce clear policy imperatives for democratic partners and for ASEAN itself.
Fundamentally, pair the spectacle with scaffolding. High-visibility summits must be followed by predictable, well-resourced programs: long-term capacity assistance for Timor-Leste (bureaucratic, judicial, customs and digital infrastructure), enforceable trade mechanisms, and maritime law aid for claimant states. One-off headline deals are politically useful; enduring influence requires institutions that outlast a presidency.
On another front, recalibrate coalition messages so they buttress ASEAN's convening role. AUKUS, the Quad and bilateral security partnerships provide important deterrence, but if their public posture reads as exclusionary, they invite hedging by ASEAN capitals – precisely the outcome they hope to prevent. Coalition diplomacy must therefore be framed as capacity-building for ASEAN, not the replacement of it. Australia's recent recalibration toward deeper ASEAN engagement offers a model of how to marry defence depth with diplomatic reassurance.
Beyond that, reduce single-point vulnerabilities in supply chains. Breaking or blunting China's REE chokehold is a multi-year project that requires investment in mining, refining and recycling across trusted partners – plus regulatory streamlining and willingness to accept higher prices for strategic security. Reopening mines, scaling allied processing capacity, and funding recycling innovation are politically hard and expensive, but they are the only durable hedge against non-kinetic coercion.
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Ultimately: strengthen realistic multilateralism. 'ASEAN's Way' – consensus, non-interference and incrementalism – is not obsolete; it is a necessary political form for a diverse region. But that model needs reinforcement through clearer dispute-resolution pathways, greater transparency around resource diplomacy, and mechanisms that make accession and integration operational rather than symbolic. If ASEAN becomes merely a backdrop for great-power pageants, smaller states will lose faith in the rules-based order they helped construct.
Moreover, the most likely near-term trajectory is managed competition – recurrent bargains, episodic crises in the South China Sea, and an intensifying scramble to secure critical inputs like REEs. Accelerated decoupling is possible but will be partial and costly; the nightmare scenario – explicit weaponisation of resource supply amid a maritime crisis – remains low probability but catastrophic if it occurs. Policymakers should therefore treat prevention as the main task: invest in institutions, diversify supply chains, and make ASEAN's membership expansion a sustained political priority rather than a one-day headline.
Timor-Leste's arrival is both an opportunity and a responsibility. The world greeted the new flag with applause in Kuala Lumpur – now the hard work begins: turning summits into systems, spectacle into sustainability, and a fragile accession into a durable bridge for regional stability.
[Kurniawan Arif Maspul is a researcher and interdisciplinary writer focusing on Islamic diplomacy and Southeast Asian political thought.]