Border Fire: What the 2025 Thailand–Cambodia Clash Reveals About the Global Era of Militarised Borders

Source; Credit: omersukrugoksu

In July 2025, the Thai–Cambodian border once again became a theatre of conflict. Heavy artillery, rocket fire, and airstrikes tore through frontier provinces, displacing hundreds of thousands of civilians and damaging hospitals, homes, and cultural sites. A ceasefire brokered within weeks proved fragile; fighting soon resumed, triggering renewed evacuations and deepening the humanitarian fallout.

While officials on both sides pointed to a May 28 skirmish that resulted in the death of a Cambodian soldier as the proximate cause, such an isolated incident cannot plausibly explain a conflict marked by sustained aerial bombardment, mass mobilisation, and coordinated cross-border strikes. The death is better understood as a political pretext: a catalyst applied to an already volatile landscape shaped by nationalist sentiment, institutional weaknesses, and the re-militarisation of borders.

To treat the 2025 clash as an anomaly would therefore be a grave mistake. Instead, it should be understood as a symptom of a broader global shift in the rapidly changing role of borders within international politics.

Borders, long assumed to be stable demarcations of sovereignty governed by diplomatic norms, seem to be increasingly re-emerging as militarised frontiers where states project power, test limits, and advance domestic political agendas through calibrated uses of force.

This article argues that this instance is not unique: it is an instance of a wider trend of the rapid militarisation of borders. Enabled by technological change and facilitated by the erosion of international and regional constraints, borders are no longer neutral lines demarcating territory.

I. Borders Are No Longer Just Lines

Contemporary border studies have begun to describe a fundamental shift in how borders operate. Scholars argue that it is no longer sufficient to understand borders as merely fixed territorial boundaries, but rather acknowledge them as “regimes of control”, increasingly acting as zones where sovereign states project power and enforce exclusion to advance their domestic political agendas.

This re-conceptualisation reflects the effects of broader shifts in global governance. Factors like the rapidly declining enforcement capacities of transnational legal and diplomatic institutions have led to fewer external constraints for states. Borderlands have thus become politically attractive arenas, spaces where force can be applied, claims reinforced and nationalist sentiment generated; all without the need to engage in all-out war.

Recent technological advancements play no small role in this trend. Improvements in surveillance capabilities, drones, and precision-guided weaponry have lowered the traditional costs associated with border conflict. States can now monitor frontier regions continuously, respond rapidly to perceived violations, and apply localised force without suffering major human losses – a prospect extremely attractive for guaranteeing continued public support. This has led to states preferring more confrontational approaches to conflict resolution, even before the deployment of diplomatic overtures.

Research by the Centre for Strategic and International Studies (CSIS) highlights in particular how the proliferation of unmanned aerial systems (UAS) has fundamentally altered state perceptions of risk and intent within contested spaces. The rapid spread of these technologies, due to their cheaper and often disposable nature, has led commanders to become more willing to employ them offensively, acting far more brazenly. Furthermore, given their cost-effective nature, which positions them as a vital tool in closing power asymmetries between states, there remains little doubt that this phenomenon will continue to proliferate.

In the Thai–Cambodian conflict, Thailand’s utilisation of loitering aerial munitions, in conjunction with advanced modern fighters like SAAB’s JAS 39 Gripen, allowed for both rapid force projection and high-precision targeting, enabling them to reach well beyond the range of simply small arms or artillery. Their deployment of strike drones, such as the indigenously developed KB-5E loitering munition, a “kamikaze” drone, allowed them to maintain consistent airborne pressure before striking, overwhelming Cambodian air defence systems.

This portends a troubling future for border disputes worldwide: as the Global Peace Index 2025 notes, the number of drone manufacturers has skyrocketed from six in 2022 to over 200 by 2024, with these systems making “conflict more accessible and more asymmetric – but with that, also more difficult to resolve”. From the Sahel to South Asia, the Thai–Cambodian conflict may herald a new era of border warfare where technological proliferation dramatically lowers the threshold for the use of force, rendering traditional diplomatic frameworks increasingly obsolete.

II. Institutional Decay and the Collapse of Constraint

The decline of international institutions has further played a massive role in the proliferation of these incidents. Originally established to provide a framework for conflict management, norm enforcement and restraint, particularly in contexts where bilateral escalation posed systemic risks, they have been severely limited by their one key drawback: their relative inability to enforce the international norms they posit.

In the Thai–Cambodian border dispute, this reality was starkly illustrated by ASEAN’s response or rather, the lack thereof. On 27 July 2025, the ASEAN Foreign Ministers issued a statement urging both Thailand and Cambodia to exercise “maximum restraint”, undertake an ‘immediate ceasefire’, and return to peaceful negotiations. However, the statement lacked any binding mechanisms to enforce compliance or deter further hostilities. Although Malaysia, the ASEAN chair, hosted ceasefire talks on 28 July 2025, successfully implementing an “immediate and unconditional” halt to fighting, there is evidence to suggest that this outcome was shaped less by ASEAN’s institutional authority than by external diplomatic pressure. Both China and the United States played decisive roles, with Chinese foreign ministry spokesperson Guo Jiakun stating that China was “deeply concerned about the current developments” and would “continue to exercise its own way to persuade and promote talks, and play a constructive role in promoting the easing of tensions and cooling down”. This exposes significant limitations surrounding the role of multi-lateral institutions as platforms for effective diplomatic dialogue – as opposed to direct major power involvement.

This is not, however, a weakness unique to ASEAN. It reflects a broader structural erosion of institutional constraint across the international order. Bodies like the European Court of Human Rights have experienced a dramatic rise in unimplemented judgments over the past two decades, with non-compliance cases increasing from 2,624 in 2001 to 9,944 by 2016. Furthermore, inherent weaknesses within decision-making, such as the veto mechanism in the UN Security Council, have led to permanent members blocking resolutions in favour of their own geopolitical interests, even when votes from other members form clear majorities. The “toothless” nature of these bodies and their inability to enforce decisions constitute a failure to disincentivise states from aggressively pursuing their national interests over safeguarding the norms of the international order.

This weakness has only been amplified in the 21st century as an emerging multi-polar order begins to crystallise. As a growing number of powers compete for some form of territorial influence, sometimes aligning themselves with major powers such as the US, Russia, or China, a loose East-versus-West dynamic has taken shape, in which the enforcement of global norms is increasingly selective or, at times, openly contested.

III. Rise of Nationalist Sentiment

The overt militarisation of borders cannot be understood without examining domestic politics as a key driver of conflict. In the Thai–Cambodian case, this relationship has a well-documented history that directly shaped the conditions for the 2025 crisis.

It began during the 2008 crisis, where the country’s political elites were deeply polarised between the “red shirt” supporters of exiled former Prime Minister Thaksin Shinawatra and the “yellow shirts”, part of the royalist-nationalist opposition coalition known as the People’s Alliance for Democracy (PAD). The appointment of Samak Sundaravej to the premiership , viewed by many as a Thaksin-aligned government, led to PAD framing his willingness to accept Cambodia’s UNESCO World Heritage bid for the Preah Vihear Temple, and avoid confrontation over the disputed border area as acts of national betrayal – popularising the notion of khai chat (selling the nation). The resulting crisis forced the government to deploy troops to the border, and by mid-July, over 1,200 soldiers from both sides were patrolling the area.

This established a self-perpetuating cycle. Thailand’s posturing provoked an equally aggressive Cambodian response, with Phnom Penh deploying 70 soldiers to the previously non-militarised Ta Krabei temple. Hun Sen (then acting Prime Minister of Cambodia)  seized the dispute to consolidate domestic support, increasing the defence budget by 68.8%, launching mass conscription, and accusing Thailand of having “cheated on history”. Nationalist mobilisation on each side justified further military deployments, which furnished new material for further mobilisation.

This cycle resurfaced in 2025, with significantly higher stakes. The same vicious cycle of nationalist sentiment emerged after Hun Sen leaked a phone call in which then-Thai Prime Minister Paetongtarn Shinawatra, daughter of Thaksin Shinawatra, appeared deferential to Cambodia and critical of her own military – a recording capitalised upon by Thai elites to accuse the government of betraying national interests, echoing the 2008 khai chat accusations yet again. The death of a Cambodian soldier on 28 May then became the pretext for sustained aerial bombardment and mass troop mobilisation.

The pattern of instrumentalising the border for domestic gain reverberates globally. Research published in the Journal of Conflict Resolution finds that “the militarisation of border control is a defining feature of contemporary international politics, driven significantly by public reactions to perceived threats of national decline, with politically insecure leaders now incentivised to implement policies like border militarisation in the hopes of prompting domestic rallying”. India’s 2020 Galwan Valley clash with China allowed the Modi government to leverage the confrontation to project strength, increasing defence spending by approximately $2.8–2.9 billion, and accelerating infrastructure development along the Line of Actual Control (the de facto border between India and China), absorbing the standoff into the ruling party’s electoral messaging. It is quite clear, then, that these borders have been militarised not because of any purely military threat, but also to satisfy domestic political demands. With weak institutional constraints and rapidly evolving technology, the threshold for this instrumentalization has dropped dramatically, leading to border conflict that become self-reinforcing.

It is not sufficient to look at the Thai–Cambodian conflict as simply a skirmish. What began with a single soldier’s death escalated into sustained aerial bombardment and mass displacement – not because the incident necessitated such violence, but rather because the structural conditions of border politics made escalation both feasible and politically rewarding.

Looked at through the lens of three interlocking forces that have driven this shift: technological proliferation has lowered the costs of conflict, enabling precision strikes with minimal domestic casualties; institutional decay has removed the guardrails that once constrained escalation, leaving regional bodies toothless without great power intervention; and nationalist sentiment has transformed borders into stages where leaders accrue legitimacy through confrontation rather than compromise.

The Thai–Cambodian conflict thus offers a preview of another emerging order, one in which the threshold for conflict has dropped, mechanisms for resolution have weakened, and the political incentives for militarisation have only intensified. Unless the international community confronts these structural drivers, the militarised border risks becoming the defining feature of 21st-century geopolitics.

Written by Arjun Diwaker

Edited by Aditya Gupta