Thai-Cambodian Dispute: When Foreign Policy Begins at Home

Thailand’s political centre of gravity has shifted dramatically following the Constitutional Court’s suspension of Prime Minister Paetongtarn Shinawatra on 1 July 2025. Initially sparked by a leaked phone call with Cambodia’s Hun Sen and exacerbated by Bhumjaithai (BJT)’s withdrawal from the coalition, the incident has snowballed into a leadership crisis. Foreign policy blunders, typically managed through diplomatic channels, have been repurposed as political ammunition in domestic power struggles.

This episode highlights a concerning trend: the increasing normalisation of using diplomatic incidents for partisan gain. This incident shows how international relations could be used to undermine rivals. The leaked conversation, in which Paetongtarn spoke deferentially to Hun Sen while criticising Thai military officials, raised diplomatic concerns. However, the real damage stemmed from domestic political exploitation of the call. This has jeopardised Thailand’s credibility amid rising regional uncertainty and sensitive border issues with Cambodia.

While one would expect domestic leaders to unite under international pressure, political damage to opponents often precedes national instability. While some parties may gain short-term advantages, it sets a dangerous precedent, leaving Thailand vulnerable to foreign actors manipulating the country’s domestic unrest for political gain.

The Prime Minister’s suspension also exposes the precariousness of executive authority in Thailand. The ruling coalition, led by Pheu Thai (PT), faces paralysis at a critical fiscal juncture, with the 2026 budget bill due for its final readings this August amid fragile legislative support. BJT’s exit has left the government with only a wafer-thin majority of 256 seats and widened cracks in the ruling coalition.

BJT’s exit has triggered broader instability, leaving the government vulnerable to defections. The lack of unity within the United Thai Nation (UTN) and a split in support for PT mean another faction’s defection could unseat the government. This internal instability diverts attention from pressing foreign policy challenges amid rising border volatility. While BJT cited the Hun Sen conversation as justification for their withdrawal, the deeper motive was political. The party sought to portray Paetongtarn’s judgment as unpatriotic and wanted to consolidate their position.

Domestic responses against PT were swift. The Constitutional Court suspended Paetongtarn following a petition by Senate President Mongkol Surasajja, who is closely affiliated with BJT. Many senators appear to have acted in concert, reflecting how institutional checks have been weaponised to enforce political outcomes. Institutions intended to protect democratic norms are now being exploited as tools for political manipulation, thereby increasing public scepticism about the due process.

The core concern is that Thailand risks losing control of its foreign policy coherence, not only because of external threats, but also due to domestic actors undermining it.

Public unrest is once again coming to the forefront, highlighted by anti-Thaksin protests on 28 June and the anticipation of another demonstration in August. These developments reignite fears of potential military intervention. Acting Prime Minister Phumtham Wechayachai asserted that top generals are committed to upholding democratic norms, but there are concerns that the military may assert influence behind the scenes. The military now favours the role of a backstage arbiter rather than a direct usurper, but this hardly guarantees stability. A divided government, which is unable to act decisively, invites not only civil discontent but also elite realignments in search of greater control.

PT’s predicament does not stem from a lack of trying. It has since asserted control of the Interior Ministry, placing loyalist Phumtham in charge. His decisions suggest a coordinated campaign to dismantle BJT’s institutional strongholds. This includes transferring key officials within the Interior Ministry, enforcing a court order involving BJT-linked land in the Khao Kradong dispute, reversing BJT’s cannabis policy by Public Health Minister Somsak Thepsuthin, and a DSI-led probe into alleged Senate election rigging. Rather than restoring authority, however, these actions further inflame tensions within the coalition, feeding the perception that PT is settling scores rather than governing at a time when real external challenges require greater unity and strategic focus.

As tension mounts, manoeuvring over who should be the next PM remains deadlocked. The People’s Party (PP) will support a new prime minister if Parliament is dissolved by the end of 2025 and their constitutional reform proposals are addressed. While they may collaborate with PT, any charter reforms will need backing from at least one-third of the Senate, where BJT holds significant power. Partnering with BJT could be pragmatic for PP. However, a BJT-PP alliance (totalling only 211 MPs) will still fall short of the 251-seat threshold required for a majority. It will also risk alienating PP’s base, echoing the backlash against PT’s alliance with conservatives. Reform efforts will stagnate if charter amendments are used as bargaining tools instead of genuine steps toward curbing unelected influence and strengthening democratic institutions.

The core concern is that Thailand risks losing control of its foreign policy coherence, not only because of external threats, but also due to domestic actors undermining it. The entanglement of diplomacy with domestic factionalism harms national interests. The border with Cambodia remains a sensitive flashpoint, with Thaksin and Hun Sen at odds, and the Thai military retaliating for previous Cambodian actions. The International Court of Justice (ICJ) case regarding territorial claims around the border underscores how Cambodia leverages global institutions to exert pressure. With formal diplomatic mechanisms stalled, the risk of miscalculation escalating into a wider security crisis has increased. In this instance, political unity is more important than ever.

Thailand stands at a crossroads. It can continue with tactical infighting, risking democratic erosion and geopolitical irrelevance, or it can initiate a serious reset through new elections, a technocratic caretaker, or a meaningful coalition reconfiguration. Yet, given the entrenched mistrust among key political parties, the prospects for such a reset appear slim. Without a decisive shift in political will, Thailand is more likely to drift into prolonged instability than to achieve lasting coherence at home or abroad.

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