A History of Cambodia-Thailand Diplomatic Relations 1950-2020

Right before Second World War II, the proponents of a new trend in historic studies boldly named ​“Nouvelle Histoire” [New History], Marc Bloch and Lucien Febvre, dismissed the conventional idea that one had to wait decades, even centuries, before considering and reflecting on what was happening there and now with the perspective of an historian. It was possible and even necessary, they asserted, to attempt writing without emotional bias or distortion ​“l’histoire immédiate”, often translated in English as ​“recent history” but perhaps more aptly as ​“instant history.” 

With the sudden explosion of military clashes at the northern border of Cambodia and near the southern tip of Thailand’s territory in June-July 2025, the international public opinion has discovered — or rediscovered — that 

1. many Khmer temples dating back from the 9^th century onwards were located within the modern boundaries of Thailand, or in mountainous areas along the Dangrek range where the outline remained unclear and contested;
2. while the Cambodian official position was to persistently appeal to international arbitration — in particular through the International Court of Justice (ICJ), Thai officials seemed divided on the matter, with some factions adamantly rejecting this approach, or even the principle of involving a third party like the ASEAN rotating presidency, for reasons that ​“had never been clearly explained”, as remarked the author of the present book in July 2025.

Everytime tension flares up at the border, a cliché widspread among Thai nationalist circles resurfaces: all the trouble originated from the French colonial policy in the area since 1863, and those who do not believe in aggressive shows of force against Cambodia are in fact complicit of neo-colonialism. With the persistent subtext that Cambodian elites were unable or unwilling to break away from that outlook. As the author recalled in Chapter 2, even after World War II and after Cambodia had gained its independence in 1953, some Thai army generals claimed that King (later Prince) Norodom Sihanouk had been ​“indoctrinated by the French to question Thailand’s sincerity.” Hence the paradox noted by a professor of political science at Chulalongkorn University, Khien Theeravit, in an article quoted in the book (“Thai-Kampuchean Relations: Problems and Prospects, Asian Survey, Vol. 22, No. 6, Southeast Asia: Perspectives from ASEAN (June 1982), pp. 561 – 576): 

Although Sihanouk was initially more sympathetic to the Thais than to the Vietnamese, in the hand he had more disputes with Thailand than with Vietnam. [p 25]

The analytical framework of a work covering seven decades of contemporary history is clearly described by the author when it seeks to explain why Cambodian-Thai relationships have gone through so many fluctuations, including military clashes: 

It employs the ​“social conflict” analysis, which views states not as unitary actors, but within which are comprised of different societal forces competing with one another and pursues foreign policies in accordance with their own ideology, interest, and strategy. As such, it is postulated that Cambodia-Thailand diplomatic relations should not be seen simply as relations between two unitary states cooperating with or securitizing against one another, but rather as a matrix of intertwining relationships between various social and political groups in both states harboring competing ideologies and/​or interests to advance their power positions at home. [p 13]

Such a premise certainly shows better prospects for historians than the partisan and peremptory assessments by self-proclaimed ​“international experts” who can hardly disguise their dislike of one or the other parties in the dispute. Going through the complexities of internal and bilateral policy in both countries — with the limitation of not covering documents in the Thai language, acknowledged by the author convincingly show that in several instances, notably the military tension around Prasat Preah Vihear from 2008 until 2011 — culminating in deadly clashes between 22 April and 3 May 2011 -, the Thai stance was ​“driven more by Thai domestic politics and power struggles rather than by real problems between the two governments at the time” [p 92]. The Cambodian reaction had obviously domestic political ramifications, and the author is right to remind us that at that time, ​“the commander of Cambodian troops overseeing the latest round of fighting at Preah Vihear was (then) Prime Minister Hun Sen’s eldest son, 33-year-old West Point Graduate Major-General Hun Manet,” [p 93] the Prime Minister of Cambodian since 22 August 2023. 

These two maps presented in the official file for the Preah Vihear inscription on UNESCO World Heritage List in 2008 reflect two visions of a major temple site in its geographical context: left, the Cambodian version, based on the 1962 ICJ decision; right, the Thai proposal dated 2007. Source: Office of the Council of Ministers, Kingdom of Cambodia [under the guidance of HE Dr. Sok An, Deputy Prime Minister], The Temple of Preah Vihear: inscribed on the World Heritage List (UNESCO) since 2008, Phnom Penh, 2010, 130 p., p 23.

Another important aspect explored here is the persisting decoupling of the relations between the two countries in regards to global geopolitics and bloc alignment. This factor may explain why the traditionally US-aligned and anti-communist Thai leadership promptly recognized the Khmer Rouge régime in 1975, and waited until the 1991 Peace Agreements to distance itself from Pol Pot’s followers — a paradox stressed by the author as he considers the Khmer Rouge as ​“communist”, a typification that was never accepted by Russia, Vietnam, or numerous independent historians later.

The book also deals with the contentious area at the southern tip of modern Thailand, in the vicinity of Koh Kood (or Koh Kut) Island. While rumors of gigantic oil and gas offshore deposits have fed countless conspiracy theories, the author reminds us that most of the related documentation on OCA (Overlapping Claimed Areas) are available online, in the open to be consulted, and that is one of the few friction points that is recognized on both sides as a field for a fruitful bilateral collaboration. 

One remark in the book conclusion particularly deserves further consideration and discussion:

Though a certain degree of nationalistic antagonism produced through historical narratives and discourses does exist between Cambodia and Thailand, it only becomes a factor affecting the two countries’ relations when the Cambodian and/​or Thai political elites need to bolster legitimacy at home. Yet, leaders in either country have not always done so simply whenever they faced a domestic legitimacy crisis. A major factor in pushing for invocation of nationalism and conflict has generally been, as mentioned in the previous points, when the two governments do not share similar ideologies and/​or core mutual strategic interests, which would have made it easier for politicized nationalism to arise. [p 131]

It would be pointless on this platform — and perhaps in general — to drift into speculation and far-fetched so-called expertise on ulterior-motive and behind-the-scene plotting. We’ll only remark that while the heated emphasis on ​“Khmer” instead of ​“Cambodian” — while the affected populations, especially in the Preah Vihear area, are of Kuy origin -, and the centrality of the territoriality of ancient Khmer temples - in particular the Ta Moan ones — in the public outrage in Cambodia raise whole new challenges to the cultural ties between the two countries. This reflects the global rise in cultural, ethnic and religious polarization that is at the core of many conflicts worldwide. The notion that border issues are just convenient gimmicks used by powers-that-be to ​“distract” public opinion from more serious matters — the regional fallout of the US aggressive protectionism, for instance — is no longer pertinent.

Also, and as a matter of course this 2020 publication could not possibly address this issue, can historians (or ​“instant historians”) still view the May-July 2025 crisis as a ​“low-intensity border conflict”, a term often used before ? [see for instance Martin Wagener, ​“Lessons from Preah Vihear: Thailand, Cambodia, and the Nature of Low-Intensity Border Conflicts,” Journal of Current Southeast Asian Affairs, 30, 3, 27 – 59 ISSN: 1868 – 4882]. The dire situation of thousands displaced families in northern and coastal Cambodia weeks after an ASEAN-brokered ceasefire — as it had been requested by the Cambodian party -, and the disruptions in Thailand’s provinces close to the border, is indicative of a more profound problem that needs to be fully grasped and solved.

As it stands, the present book is the first to cover a comprehensive history of diplomatic relations between Thailand and Cambodia, starting from the establishment of official diplomatic ties in 1950 to the present. The fact that it is the work of a Cambodian scholar bodes well for the future of international relations studies, and hopefully for a rekindled spirit of dialogue and mutual understanding in the region.