Cambodia Begins Maritime Conciliation with Thailand, Drawing Lessons from Timor-Leste

Timor-Leste’s landmark use of compulsory conciliation under the UN Convention on the Law of the Sea (UNCLOS) offers Cambodia valuable lessons as it embarks on the same legal process with Thailand, with speakers stressing that international law can reopen stalled negotiations, but success ultimately depends on confidence-building, political will and sustained dialogue. Speaking at a public lecture hosted by the Cambodian Center for Regional Studies (CCRS) at Cam-ASEAN International School today, July 3, Timor-Leste ambassador to Cambodia, Marcos dos Reis da Costa, shared his country’s experience as the first nation to invoke compulsory conciliation under UNCLOS to settle a maritime boundary dispute with Australia. The lecture came just weeks after Cambodia formally initiated compulsory conciliation proceedings with Thailand over their overlapping maritime claims in the Gulf of Thailand, making Cambodia only the second country to use the rarely invoked UNCLOS mechanism. Opening the event, CCRS distinguished senior advisor Pou Sothirak said Timor-Leste’s experience could serve as a practical reference as Cambodia seeks a peaceful resolution to its maritime dispute with Thailand while maintaining separate bilateral mechanisms for land border issues. “It was regarded as a breakthrough diplomatic mechanism which was used to resolve the intractable deadlock over maritime boundary,” he noted. Sothirak explained that Cambodia’s decision to pursue compulsory conciliation followed Thailand’s termination of the 2001 Memorandum of Understanding governing maritime negotiations, arguing that the UNCLOS mechanism had effectively reopened a diplomatic channel. “After the MoU closed, there’s no way, no channel,” he said, during his closing remarks. “Cambodia has done a great job, in my opinion, to engage this process. Cambodia has reopened the negotiation path,” he added. Marcos recounted how Timor-Leste initiated compulsory conciliation against Australia in April 2016 after years of unsuccessful bilateral negotiations over maritime boundaries. “It was a very bold move from a small nation like Timor-Leste against a giant nation like Australia,” he said. “It is not about winning or losing, but we had to try because we believe in international law,” he added. The process, which lasted from 2016 to 2018, culminated in the signing of a landmark maritime boundary treaty in New York, establishing a permanent maritime boundary and a new revenue-sharing arrangement for the Greater Sunrise gas field. Marcos said one of the biggest milestones came early in the proceedings when the conciliation commission ruled that it had jurisdiction despite Australia’s objections, compelling Canberra to negotiate. “For us it was already good enough to see that Australia could now sit with us to negotiate and discuss the maritime boundary,” he said. Throughout the lecture, Marcos repeatedly emphasised that compulsory conciliation should not be viewed as litigation but as a structured diplomatic process designed to facilitate dialogue. “This is a process that brings states to the table, to have dialogue,” he said. “We just would like to know under international law what are our rights, and that’s it,” he continued. Rather than focusing solely on legal arguments, Marcos highlighted confidence-building as the decisive factor behind Timor-Leste’s eventual success. He said both governments deliberately maintained confidentiality during negotiations, avoided inflammatory public rhetoric and ensured that broader bilateral cooperation continued despite the dispute. “We like megaphone diplomacy,” he said, with a smile. “But we also learned during this period that we had to restrain ourselves,” he noted. He explained that negotiations remained confidential until both parties agreed on what information could be released publicly. “What we agreed, we told each other. What we didn’t agree, that stayed between us,” Marcos said. He added that Timor-Leste continued engaging with Australia across other areas throughout the conciliation process. “We negotiated government-to-government. All cooperation with Australia continued. There was no problem at all,” he said. Reflecting on Timor-Leste’s broader diplomatic strategy, Marcos said his country drew heavily on lessons from its struggle for independence. “We fought against the regime in Indonesia. We did not fight against the Indonesian people,” he said. “It makes the difference,” he added. He said Timor-Leste also invested heavily in public diplomacy by engaging universities, civil society, overseas communities and international supporters while ensuring the government remained the primary source of official information. Asked how Timor-Leste prevented sovereignty issues from becoming politically divisive, Marcos said maritime boundaries had been treated as a national rather than partisan issue. “In Timor-Leste, the issue of sovereignty and borders is a national issue. It’s not a partisan issue,” he said. “All political parties, whether in government or opposition, have the same stance when it comes to our sovereignty,” he noted. He added that regular briefings to parliament, transparent public communication and public education helped reduce opportunities for political exploitation and misinformation. “We try to counter misinformation with facts and official statements,” he said. “When people see that the government is working hard and following the right legal procedures, they are less likely to be swayed by misinformation,” he added. During the discussion, participants also asked about the role of youth in safeguarding sovereignty. Marcos said Timor-Leste’s younger generation had become active participants in public discussions on maritime boundaries. “They understand that the future of our country depends on our resources and our sovereignty,” he explained, adding “They are not just passive observers; they are active participants in the national dialogue”. Summarising the day’s discussions, Sothirak identified six major lessons from Timor-Leste’s experience, describing compulsory conciliation as an important diplomatic process rather than a courtroom proceeding. “Compulsory conciliation is not a court but a process,” he said. He stressed that the mechanism allows disputing parties to resume negotiations, supported by impartial conciliators, even though the commission’s recommendations themselves are not legally binding. “International law is a great equaliser,” Sothirak said. “Small states have the same rights as big states,” he added. He also underlined the importance of confidence-building measures, saying they create the conditions necessary for preventive diplomacy and eventual conflict resolution. “Without confidence-building measures from the start, you will never have anything else,” he said. Looking ahead, Sothirak welcomed Thailand’s decision to participate in Cambodia’s compulsory conciliation proceedings and expressed h