Thai-Cambodian Tensions: For Thailand, Appeasement Will Not Hold the Line

In one fell swoop, Thai Prime Minister Paetongtarn Shinawatra has undermined her ruling Pheu Thai-led government and complicated Bangkok’s attempts to resolve a long-running border dispute with Cambodia.

Her political naivete was evident in a Sunday (15 June) phone call with Cambodian Senate President Hun Sen. In the leaked call, which was apparently released by the Cambodian side, Paetongtarn is heard appeasing Hun Sen to an alarming degree. She even called a senior Thai commander on the frontline “an opponent”.

The political blowback has come thick and fast from both ends of Thailand’s political spectrum. The two camps’ shared frustration with the Pheu Thai-led government’s handling of the border contestation with Cambodia around the undemarcated Emerald Triangle represents a damning verdict. The dispute has been simmering for months as Cambodia encroached on the contested ground, with tensions peaking following a 28 May skirmish that killed a Cambodian soldier.

The leaked call has cemented the narrative that the Pheu Thai leadership is “pro-Cambodia” out of personal rather than national interest and has shattered what little trust remained in the government. Indeed, it has never made sense for the government to be excessively appeasing towards Cambodia when Thailand can utilise its material military and economic edge. Setting aside questions of domestic political reconfiguration, the more pressing challenge is how Thailand should proceed when contending with an openly unfriendly Cambodia. The current situation contrasts sharply with the early days of the Paetongtarn government, when Thailand-Cambodia relations were exceedingly warm.

The Thai-Cambodian border dispute lies in genuine sovereignty disagreements inherited from the colonial era. Article I of the 1904 Franco-Siamese Treaty dictated that the frontier between French-controlled Cambodia and Siam (Thailand’s former name) follow the natural watershed line. The 1907 Annex I map drawn by France contradicted this principle and disadvantaged Siam. Despite its flaws, Annex I went uncontested by Siam for decades. Power asymmetries with France made any Siamese resistance unviable. This formed the basis of the International Court of Justice (ICJ)’s 1962 ruling on the Preah Vihear Temple in Cambodia’s favour. It is unsurprising, then, that Cambodia today insists on using the French-drawn 1:200,000 Annex I map and going to the ICJ. Thailand uses 1:50,000 topographic maps. The maps underpin the watershed principle and place much of the disputed area within Thai territory. Thailand also views bilateral frameworks as better serving its interests.

Cambodia’s release of the controversial Paetongtarn-Hun Sen call appears to be aimed at deepening existing rifts between Pheu Thai and the armed forces.

Facilitated by the Paetongtarn government’s slow and lacklustre response, notably the week-long delay in issuing an official statement after the initial flare-up, Cambodia has displayed diplomatic shrewdness in portraying Thailand as an overbearing and xenophobic larger neighbour. Cambodia submitted the case to the ICJ on 15 June, the 63^rd anniversary of its legal victory against Thailand over the Preah Vihear Temple. Hun Sen, with his shrewd sense of theatre, has likened Thailand to Russia, and has cautioned that the contested site could end up like Gaza without an ICJ ruling. The mass return of Cambodian workers from Thailand is another theme pushed by the Cambodian leadership, with Hun Sen declaring, “our citizens should leave before they are expelled or subjected to abuse and prejudice.”

Cambodia’s release of the controversial Paetongtarn-Hun Sen call appears to be aimed at deepening existing rifts between Pheu Thai and the armed forces. It is unlikely that there will be another coup: the Thai military is enjoying a rare surge in popularity and can assert influence without formal power seizure that would risk international isolation. If a coup emerges, Cambodia would likely capitalise on any perceived Thai aggression. Alternatively, if Paetongtarn remains and persists with leniency under the banner of restraint, Hun Sen could double down on the boast that he exerts influence over Thailand’s government.

If history is any guide, most recently seen through the 2003 Phnom Penh riots, it is only when tangible Thai pressure is applied robustly that Cambodia retreats. As such, Thailand is better off toughening up through security channels. The Thai military should avoid initiating offensive operations against its Cambodian counterpart, but must leave no doubt that its defensive capabilities are decisive if called upon. More concretely, Thailand might consider conducting drills near but not within sensitive border areas to highlight the country’s ability to mobilise rapidly and deny incursions. Given Cambodia’s recent live-fire maritime exercise off disputed Koh Kood, such a move from Thailand would hardly be disproportionate.

Apart from military action, Thailand should consider casting the spotlight on Cambodia’s scam industry. This is endorsed by numerous Thai commentators, such as MP Rangsiman Rome of the People’s Party, and reflected in the Army’s action to ban Thais from crossing over to work in Cambodian entertainment venues and casinos. According to crime and trafficking researcher Jacob Sims, the scam industry may account for over half of Cambodia’s GDP. It therefore stands to reason that such a lucrative industry substantially enriches the country’s leadership, making it a strategic pressure point. Needless to say, the scam industry also directly endangers Thai citizens.

The leaked call gives Thailand a ready-made case to expose the Cambodian government’s lack of diplomatic sincerity. To further bolster its international leverage, particularly under the assumption that France is sympathetic to the Cambodian cause, Thailand should work closely with its security ally, the US. The conditions are favourable, with the Trump administration targeting Cambodia-linked scams and considering placing Cambodia among countries subject to US travel bans. Direct US intervention is unlikely given Washington’s preoccupation with the Israel-Iran escalation. But closer US cooperation on the issue could discourage Cambodia from further internationalising the Thai-Cambodian dispute.

Finally, if dragged to the ICJ, Thai authorities should deflect the pressure by demanding the Cambodian ratification of the United Nations Convention on the Law of the Sea. This would undermine Cambodia’s claim against Thailand in a maritime dispute in the Gulf of Thailand.

The best realistic scenario would be to “freeze” the dispute, which can never be resolved to the satisfaction of both parties as they each hold legitimate claims and cannot find a mutually acceptable path forward.

Practically, this requires both sides to honour the agreement to return to their pre-clash positions. For Cambodia, that means genuinely filling in the trenches and withdrawing troops — and not merely “readjusting” them, as Hun Sen said. For Thailand, that means a corresponding adjustment of its own troop positions and the easing of border restrictions. Good neighbourly relations with Cambodia must always be the goal, but that must work in tandem with credible Thai deterrence. Otherwise, Thailand will remain vulnerable to repeated Cambodian provocations.

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