Kuala Lampur, 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 sl...