Mediation rejected: Why Thailand says no to a third party in its dispute with Cambodia

Beyond the noise of weapons, a diplomatic theatre is also taking shape, with Thailand repeatedly rejecting any direct external mediation, particularly with regard to Cambodia's request for third-party intervention. Why this categorical refusal of third-party mediation, when the international community is stepping up its calls for peace?

To understand this, we need to delve into history, national pride, internal power balances and the lingering influence of the colonial past.

The History of a Refusal: Between Sovereignty and Nationalism

The Colonial Roots of the Dispute

The dispute between the two kingdoms is rooted in the ambiguities of the borders inherited from French Indochina. The Preah Vihear temple, a UNESCO World Heritage Site, has been a source of tension since 1907, when the area was incorporated into French-administered Cambodia, with Bangkok always contesting the validity of these boundaries.

Although the International Court of Justice (ICJ) recognised Cambodian sovereignty in 1962 and then extended the so-called adjacent zone in 2013, several sections of the border remain disputed, with each side accusing the other of aggressive manoeuvres or sedition disguised as self-defence.

Sovereignty as a bulwark

For Thailand, accepting third-party mediation would mean recognising a challenge to its sovereignty over territories it considers ‘national’. Insisting on a bilateral settlement allows it to portray itself as a state in control of its own decisions, impervious to external pressure.

This choice is regularly expressed by political and military leaders, for whom ‘the defence of territorial integrity cannot tolerate interference’.

Thailand's Strategy: Dialogue, Yes, but Without Intermediaries

Prioritising ASEAN and Regional Dialogue

Thailand is not completely closing the door to dialogue: it says it is ‘ready to negotiate in a bilateral framework or through ASEAN’, notably through Malaysia, which will hold the rotating presidency of the regional organisation in 2025. This allows it to show diplomatic goodwill while retaining control over the format and pace of negotiations.

‘We have tried to find a compromise because we are neighbours, [...] we remain open to ASEAN mediation,’ said the spokesperson for the Thai Ministry of Foreign Affairs.

Mistrust of Western or Multilateral Intervention

Bangkok believes that the involvement of external powers could ‘dilute’ the legitimacy of the process, increase domestic pressure, or impose solutions that are incompatible with its concept of sovereignty.

Previous experiences, such as the Preah Vihear temple dispute, which was referred to the ICJ, are seen as symbolic humiliations resulting from an international reinterpretation of a history in which Thailand considers itself wronged.

Popular Support and Political Instrumentalisation

Nationalist Factor

The tension surrounding the mediation is also explained by nationalist pressure in Thailand. The loss of Preah Vihear is seen by a significant section of the population as a historical affront. Successive governments have therefore exploited this tension to rebuild national consensus when the country is going through an identity or economic crisis.

In times of slow growth, accumulated debt or internal political divisions, the exacerbation of the dispute has a ‘rallying around the flag’ effect.

Political Calculations and Strengthening of the Army

Today's leaders, aware of the army's influence and the tradition of political instability, are taking a hard line to avoid any suspicion of weakness.

Rejecting mediation also protects them from disapproval by the military and part of the public, who see calls for international arbitration as an unacceptable surrender.

Risks and consequences of refusal

Escalation, the inevitable companion of isolation

The decision to cut itself off from independent mediation increases the risk of escalation. As the death toll rises and the exodus continues, the international community is growing impatient and threatening sanctions or increased pressure. The UN, the United States, China and the EU are stepping up their calls for de-escalation, but their messages are falling on deaf ears, locked in a spiral of retaliation and reprisals.

Bilateralism put to the test

While the bilateralism advocated by Thailand offers an illusion of control, it is proving precarious in a climate of extreme tension, where every incident, such as the death of a Cambodian soldier or the strike on a civilian installation, can set the powder keg alight. The absence of a neutral third party hinders the building of mutual trust, the cornerstone of lasting peace.

Precedents and the Art of Mutual Deterrence

The Preah Vihear theatre is not an isolated precedent. From 2008 to 2011, similar clashes erupted, leading to the deaths of dozens of soldiers and civilians, the temporary establishment of a ceasefire supervised by external observers, and then tentative attempts at demilitarisation under the auspices of the UN and the ICJ.

With each new outbreak of violence, the same refrain is heard: ‘direct talks’, ‘rejection of third parties’, then, under international pressure, a temporary opening to regional mediation strictly supervised by Bangkok.

Between Truth, Interests and the Noise of Weapons: The Discreet Voices of Allies

Even among traditional partners, support is not absolute. Some within ASEAN, such as Malaysia, are trying to play the go-between, without ever questioning the ‘format favoured by Bangkok’.

Regional and international powers, while calling for dialogue, are avoiding imposing overly active mediation, aware of the risk of further radicalising Thailand's position.

As for Cambodia, which is stepping up its appeals to the UN, it is struggling to obtain more than a condemnation in principle. The international community is content for the time being to play the role of a powerless observer, even though lives are being lost every day as a result of this refusal to allow third-party intervention.

The Wall of History and the Horizon of Possibilities

Thailand's refusal to accept third-party mediation in its border dispute with Cambodia is rooted as much in the painful history of colonial division as in its desire to assert its sovereignty in the face of any form of foreign pressure.

Driven by heightened nationalism and fears of internal political instability, the doctrine of ‘bilateralism at all costs’ has now reached a tragic impasse.

Far from bringing peace, this refusal is fuelling the fire: more than 138,000 people have been displaced, dozens have been killed, and a climate of fear and hatred has been reignited. While Thailand remains open to ‘regional’ mediation, this can only take place on terms set by Bangkok, without losing face or weakening its internal power.

Cambodia, for its part, continues to seek a solution in the multilateral arena, without much concrete response.

The epilogue to this tragedy has not yet been written. But as long as fear of interference, the legacy of colonial wounds and the need for national unity remain the guiding principles of Thai politics, the role of the third party, which has been a source of hope in other times and places, will remain closed on the scene of Southeast Asia's most disputed border.

This border saga thus demonstrates that, when faced with national memory and interests, the voice of the third party – even when well-intentioned – often comes up against the wall of pride and sovereignty. A lasting lesson for all peacemakers around the world.