Cambodia–Thailand Border Tensions in a Changing International Order: Historical Lessons and Contemporary Risks

Historically, relations between Cambodia and Thailand have been shaped by recurrent tensions and territorial disputes. Following the decline of the Angkorian (Khmer Empire) in the 15th century, Siam (present-day Thailand), particularly during the Ayutthaya period, expanded its influence and control over parts of Cambodian territory. These historical grievances continue to inform contemporary border disputes and mutual mistrust between the two neighboring states.

In the current international environment, Cambodia faces heightened risks amid a global resurgence of conflict and power politics. Ongoing wars, such as the Russia–Ukraine war, the Israel–Palestine war, and recent U.S. military actions involving Venezuela, demonstrate a weakening of the international order and the persistence of an anarchic global system. This condition aligns closely with realist theories of international relations, which argue that the international system lacks a central authority capable of enforcing rules and preventing aggression.

Realist scholars, including Kenneth Waltz, emphasize that states exist in a self-help system in which survival is the primary objective. In such a system, states seek to maximize power, particularly military capability, to deter threats or defend against stronger rivals. When a state feels insecure, it may attempt to balance power through alliances; otherwise, it risks coercion or occupation by stronger states. This logic echoes Thucydides’ famous observation in The Peloponnesian War: “The strong do what they can, and the weak suffer what they must.” The rise of Athenian power and the fear it generated in Sparta ultimately led to war, illustrating how power imbalances can trigger conflict.

Similarly, Machiavelli underscored the primacy of military strength and national security, arguing that an unarmed state cannot ensure its survival in a hostile environment. These classical and modern realist insights remain relevant in understanding contemporary border conflicts.

Historical precedents further illustrate the limitations of international intervention. After World War II, the international system became bipolar, dominated by the United States and the Soviet Union. Despite the establishment of the United Nations, Tibet, functioning as a de facto independent state after the collapse of the Qing Dynasty in 1911, was invaded by China in 1950. The absence of effective international intervention raises critical questions about the capacity of global institutions to protect weaker state.

Several factors explain the lack of meaningful UN action in the Tibetan case:

1. Ambiguous International Status
   Although Tibet exercised autonomy after 1913, few states formally recognized it as a sovereign country. Most governments acknowledged Chinese suzerainty over Tibet, making it difficult for the UN to treat Tibet as an independent state under international law.
2. Cold War Priorities
   China’s invasion occurred during the early Cold War, when global attention was focused on the Korean War. Western powers prioritized containing communism elsewhere rather than confronting China directly over Tibet.
3. China’s Rising Power and UN Constraints
   At the time, the People’s Republic of China had not yet assumed China’s seat at the UN, which complicated institutional responses. Many states also feared escalating tensions with a rising China.
4. Limited Diplomatic Leverage
   Tibet lacked UN membership, embassies, and strong alliances. Appeals to the UN and to India failed to generate decisive support, and India ultimately recognized China’s sovereignty over Tibet in 1954.
5. Symbolic UN Responses
   Later UN resolutions condemned human rights violations in Tibet, but these were non-binding and lacked enforcement mechanisms, especially after China became a permanent member of the UN Security Council with veto power.

These historical experiences raise an important question.  

Could Cambodia face a similar fate to Ukraine, where territory has been occupied by a stronger neighbor, or to Tibet, which lost effective control over its land despite the existence of the United Nations?

From a realist perspective, Cambodia’s relative weakness compared to Thailand, in terms of economic capacity, military strength, population size, and overall power, creates potential vulnerabilities. Following clashes between July and December 2025, Thai military forces reportedly deployed advanced weaponry, including F-16 and T-50 aircraft, causing significant destruction to infrastructure such as bridges, schools, residential areas, and government buildings, as well as loss of civilian lives. Despite ceasefire agreements reportedly signed in Kuala Lumpur under international observation, concerns persist that Thai forces have not fully withdrawn from disputed areas. Some analysts fear that Thailand could pursue territorial consolidation strategies similar to those employed by Russia in Ukraine or China in Tibet.

However, Cambodia’s situation differs from Tibet’s in several critical ways. Cambodia is a recognized sovereign state, a full member of the United Nations, and maintains diplomatic missions worldwide. These factors provide Cambodia with legal and diplomatic avenues to pursue international remedies. From a liberalist perspective, international institutions, diplomacy, economic interdependence, and legal mechanisms, such as the International Court of Justice (ICJ), offer pathways for peaceful conflict resolution. Liberal theory emphasizes that long-term stability depends on cooperation, trade, respect for international law, and the promotion of shared political and economic interests.

Nevertheless, given the increasingly unstable global environment, Cambodia must remain vigilant. Historical patterns suggest that Thailand has, at various points, sought territorial expansion at Cambodia’s expense, particularly following periods of Cambodian weakness.

To safeguard its sovereignty and territorial integrity, Cambodia should consider the following measures:

1. Pursue International Support through Diplomacy
   Actively engage the United Nations, regional organizations, and major powers to frame Thailand’s actions as violations of international law.
2. Seek Legal Redress
   File complaints with the International Court of Justice (ICJ) and other relevant international legal bodies.
3. Strengthen Defense Capabilities
   Invest in modernizing military and defense infrastructure to enhance deterrence.
4. Enhance Economic and Institutional Strength
   Promote economic growth through education reform, anti-corruption measures, and good governance.
5. Build Strategic Alliances
   Develop balanced partnerships with stronger states to enhance security while preserving strategic autonomy.
6. Promote Domestic Production and Economic Resilience
   Reduce dependency and strengthen national resilience through domestic industry and innovation.

In conclusion, while Cambodia faces genuine risks in an increasingly anarchic international system, it also possesses diplomatic, legal, and institutional tools that were unavailable to historical cases like Tibet. How effectively Cambodia mobilizes these tools will be crucial in determining whether it can prevent territorial loss and secure long-term national sovereignty.

References

Classical and Modern International Relations Theory

Ø  Thucydides. (1972). History of the Peloponnesian War (R. Warner, Trans.). London: Penguin Classics.
(Original work written c. 5th century BCE).

Ø  Machiavelli, N. (1998). The Prince (H. C. Mansfield, Trans.). Chicago: University of Chicago Press.
(Original work published 1532).

Ø  Waltz, K. N. (1979). Theory of International Politics. New York: McGraw-Hill.

Ø  Mearsheimer, J. J. (2001). The Tragedy of Great Power Politics. New York: W. W. Norton & Company.

Historical and Legal Cases

Ø  Goldstein, M. C. (1997). The Snow Lion and the Dragon: China, Tibet, and the Dalai Lama. Berkeley: University of California Press.

Ø  Van Walt van Praag, M. (1987). The Status of Tibet: History, Rights, and Prospects in International Law. Boulder: Westview Press.

Ø  United Nations General Assembly. (1959). Question of Tibet (Resolution 1353 (XIV)).

Ø  United Nations Charter. (1945). San Francisco.

Contemporary Conflicts and International Order

Ø  United Nations. (2022–2025). Reports on the Situation in Ukraine.

Ø  International Crisis Group. (2024). Global Conflict Tracker.

Ø  Nye, J. S. (2004). Soft Power: The Means to Success in World Politics. New York: PublicAffairs.

Regional and Diplomatic Context

Ø  Acharya, A. (2014). The End of American World Order. Cambridge: Polity Press.

Ø  ASEAN Secretariat. (2023). Treaty of Amity and Cooperation in Southeast Asia.

About the author: 

Thoeun Vongdy has been currently working in Japan International Cooperation Agency in Social Development & Governance Sections. He also serves as a lecturer in various universities in the Discipline of International Relations, Educational Psychology, Global Studies, etc. He also used to work for the foreign mission including Embassy of India in Cambodia. He obtained Master Degree of Politics, Specialization in International Relations from Jawaharlal Nehru University (JNU), India. He has been pursuing Ph.D. of International Relations at University of Cambodia (UC). His interest papers in world politics, India-Cambodia, China-Cambodia as well security issues in world affairs.