JULY 7 — One of the most enduring strengths of the Association of Southeast Asian Nations (Asean) is not the absence of disputes among its members. Rather, it is the consistent preference for diplomacy over war, negotiation over coercion, and dialogue over prolonged confrontation.

The latest maritime disagreement between Thailand and Cambodia demonstrates precisely why Asean continues to matter.

Last month, Thailand decided to terminate the 2001 Memorandum of Understanding governing overlapping maritime claims in the Gulf of Thailand. The agreement had sought to provide a framework for joint development of offshore oil and natural gas resources in disputed waters. Although negotiations under the framework had proceeded slowly for more than two decades, it nevertheless represented an important diplomatic bridge between Bangkok and Phnom Penh.

The stakes are hardly insignificant.

The overlapping maritime area is believed to contain energy resources worth as much as US$300 billion, including approximately 11 trillion cubic feet of natural gas and significant oil reserves. In an era when energy security has become inseparable from national security, both Thailand and Cambodia have compelling reasons to seek a peaceful settlement rather than prolong uncertainty.

Cambodia’s response has been equally revealing.

Instead of escalating militarily after Thailand withdrew from the Memorandum of Understanding, Phnom Penh chose to invoke the compulsory conciliation mechanism under the United Nations Convention on the Law of the Sea (UNCLOS). The procedure has been used only once previously, when Australia and Timor-Leste successfully resolved a decades-long maritime dispute through compulsory conciliation between 2016 and 2018.

That precedent deserves closer attention.

The Australia–Timor-Leste experience showed that compulsory conciliation is neither arbitration nor litigation. Rather, it provides an institutional framework within which parties continue negotiating under international supervision without surrendering their sovereignty. It is diplomacy structured by international law rather than diplomacy replaced by judicial decree.

Cambodia appears to believe that the same mechanism can create sufficient confidence for both sides eventually to return to meaningful negotiations.

Thailand, meanwhile, has continued to insist that bilateral negotiations remain its preferred avenue while simultaneously affirming that UNCLOS remains the governing legal framework for maritime issues. Bangkok has therefore rejected the notion that terminating the Memorandum of Understanding represents an abandonment of diplomacy. Instead, Thai leaders argue that direct negotiations should continue under a clearer legal basis.

This distinction matters.

Although both governments disagree over procedure, neither has renounced diplomacy itself.

That is precisely where Asean’s political culture becomes visible.

Outside observers often criticise Asean for lacking enforcement mechanisms or binding dispute settlement procedures comparable to those of the European Union. Yet such criticism frequently overlooks Asean’s historical experience.

The organisation was founded in 1967 by states that possessed fresh memories of colonialism, insurgencies, ideological rivalry and interstate suspicion. Asean was never intended to eliminate disagreements. Rather, its founders sought to ensure that disagreements would not become wars.

For nearly six decades, this objective has largely been achieved.

Even during periods of serious bilateral tension, Asean member states have repeatedly returned to consultation, dialogue and confidence-building.

The Thailand–Cambodia relationship itself has experienced repeated cycles of friction, including disputes surrounding the Preah Vihear Temple, differing interpretations of border demarcation, and occasional military confrontations. Yet neither government has fundamentally abandoned diplomatic engagement.

Indeed, Cambodia’s decision to pursue UNCLOS conciliation instead of military escalation reinforces Asean’s long-standing norm that legal and diplomatic instruments should always be exhausted before coercive measures are contemplated.

This is an important signal not only for Southeast Asia but also for the wider Indo-Pacific.

Elsewhere, maritime disputes increasingly become theatres for strategic competition among major powers. Naval deployments, freedom of navigation operations and coercive signalling have become increasingly common.

Asean has consciously attempted to preserve a different strategic culture.

The Asean Outlook on the Indo-Pacific rests upon dialogue, inclusiveness and practical cooperation rather than bloc confrontation. The Thailand–Cambodia maritime dispute, despite its complexity, remains broadly consistent with that philosophy because both sides continue seeking peaceful avenues for settlement.

This should not be mistaken for weakness.

Diplomacy requires patience, institutional memory and political restraint. It often produces incremental rather than dramatic results. Yet history suggests that negotiated settlements tend to prove far more durable than outcomes imposed through force.

The potential economic benefits also reinforce the logic of compromise.

Joint development of offshore energy resources would strengthen both economies, improve regional energy security and provide greater confidence to international investors. Continued uncertainty, by contrast, delays exploration, discourages investment and leaves valuable resources undeveloped for years.

The costs of confrontation therefore extend well beyond questions of sovereignty.

They affect economic growth, energy resilience and regional stability.

Asean’s greatest comparative advantage has always been its ability to reduce strategic uncertainty through continuous dialogue. It has done so despite differences in political systems, economic development and historical experiences among its member states.

The current disagreement between Thailand and Cambodia should therefore not be interpreted as evidence that Asean diplomacy has failed.

Quite the opposite.

The real test is not whether disagreements emerge—they inevitably will—but whether member states continue choosing diplomacy after those disagreements arise.

Thus far, both Bangkok and Phnom Penh have done precisely that.

The termination of one memorandum does not terminate diplomacy itself. If anything, Cambodia’s resort to UNCLOS and Thailand’s continuing commitment to negotiations illustrate that diplomacy remains the preferred language of Southeast Asia.

That remains Asean’s greatest strategic achievement after almost sixty years.

Not perfect harmony, but the institutional habit of choosing dialogue over conflict whenever the stakes become highest.