The Gulf of Thailand forms the second axis of the Cambodia-Thai border dispute. The 27,000-square-kilometer Overlapping Claims Area has been disputed since 1972 and is estimated to hold some 1.6 billion barrels of oil and 17 trillion cubic feet of natural gas. Thailand terminated the 2001 memorandum of understanding governing talks over the OCA in early 2026, after fighting along the two nations’ disputed land border in July and December 2025. The outbreak of war reignited historic territorial and political animosities between the two Southeast Asian states and resulted in a border closure that still persists.
The immediate cause of the fighting was a calculated political leak by Cambodian Senate President Hun Sen of a private 17-minute telephone conversation with Thai Prime Minister Paetongtarn Shinawatra. The recording exposed Paetongtarn adopting a deferential posture toward Phnom Penh while offering critical remarks regarding her own military commanders.
As Hun Sen no doubt intended, the political fallout in Bangkok was swift. The leak locked Thai political elites into a severe audience cost escalation trap, where public outrage severely restricted their diplomatic flexibility. Paetongtarn’s political credibility evaporated almost overnight, and a wave of hyper-nationalism culminated in her suspension and removal from office by the Constitutional Court. Domestic political discourse in Thailand became thoroughly militarized, effectively ending any immediate possibility of bilateral compromise with Cambodia.
