By Serena Bush, Charles University Prague

26 March 2026

It has been more than half a century since the Vietnam War concluded – time enough for memories to fade. But as a war in the Middle East rages and amid current nuclear posturing, it is worth recalling the concealed nuclear threats made by the USA as its efforts to secure victory in Southeast Asia bogged down.

US nuclear threats during the Vietnam War were constructed as propositions of finalizing war instead of legitimate war-fighting plans; the use of nuclear possibilities across various administrations was present, as seen under the presidencies of Dwight D. Eisenhower and Richard Nixon. In public, such was not the case; the US administration made sure to deny that nuclear use was being publicly considered. Therefore, nuclear threats became unspoken possibilities as outward acknowledgment would form domestic backlash, alarm, and escalation. US nuclear threats in Vietnam were thus limited by domestic and international political opposition, particularly after widespread public backlash and congressional concern generated following the Gulf of Tonkin Incident and Gulf of Tonkin Resolution in 1964, which intensified scrutiny of escalation under the administration of Lyndon B. Johnson. Vietnam’s neighbor, Cambodia, quickly became part of the Cold War’s legacy, as Communist ideology and arms spread through the jungles of Cambodia.

The plight of Cambodia during the Cold War remains a testament to how global conflicts and the stance of deterrence manifest in various forms across different generations. As many scholars link the bombings of the Ho Chi Minh Trail to the rise of the Khmer Rouge, the association of genocide is exposed. While many current survivors of the Cambodian Genocide prefer to forget such difficult times, the pain still lurks, stories become untold, but psychological and physical reminders are visible in everyday life in Cambodia. Analyzing this period requires understanding how Cold War nuclear logic, superpower rivalry, and American intervention reshaped Cambodia’s political, social, and physical landscapes. The rise of the Khmer Rouge in Cambodia must be viewed through the lens of decades of political instability, foreign intervention, and the realities of Cold War era conflict. The political climate was embedded with conventional warfare and nuclear proliferation, where technological advances represented arms production but also ideological dominance, strategic deterrence, and the fear of annihilation. Left between two ‘stoic’ and determined superpowers, the USSR and the USA, Cambodia became the playground of two large powers fighting for dominance, where deterrence through destruction was perceived as a victory. The combination of covert warfare and failed diplomacy ultimately pushed the nation toward a brutal genocide.

Nuclear-era logic

Cambodia gained independence from French rule in 1953 under the leadership of Prince Norodom Sihanouk. Prince Sihanouk at first remained a neutral force, intending to lead Cambodia through an increasingly volatile time at the height of the Cold War. However, as the war in neighboring Vietnam became more prevalent, neutrality became unattainable. North Vietnamese troops used areas in eastern Cambodia as extensions of the Ho Chi Minh Trail, turning a neutral state into a strategic pawn in global Cold War calculations. This set the stage for Cambodia becoming a target in the broader U.S. strategy to contain communism in Southeast Asia. This strategy reflected conventional containment and nuclear-era logic, where the projection of overwhelming force served as a warning to adversaries and a demonstration of technological and strategic superiority. Deterrence is defined as containment, proliferation control, and displays of technology executed to defeat the other without explicitly targeting the opposing side through traditional war methods. In Cambodia’s case, the logic of nuclear-era deterrence was extended to justify conventional bombings and large-scale interventions, treating a neutral country as a sacrifice in the pursuit of global balance of power.

In 1969, the United States began a bombing campaign known as Operation Menu, authorized by President Richard Nixon and Secretary of State Henry Kissinger, without congressional approval. Within four years, more than 540,000 tons of bombs were dropped on Cambodian territory. The attacks targeted alleged communist hubs and supply lines in rural provinces, ultimately devastating local villages, farms, and local populations. Bombs used included general-purpose explosives, weapons such as napalm, white phosphorus, and cluster munitions. This campaign exemplified the militarization of US foreign policy, where technological might and strategic deterrence overrode humanitarian considerations. This completely changed the country physically, as all the explosives mentioned transformed the landscape into a desolate terrain. Although conventional, the way these weapons were used had comparable effects to the end of the nuclear age, where territorial annihilation was viewed as a valid instrument of deterrence without provoking actual atomic warfare. Cambodia thus became a testing ground for Cold War logic, where large-scale destruction itself became a form of strategic signaling.

Agent Orange

Agent Orange, a dioxin-based herbicide that defoliated forest cover, was first used by the U.S. military in Vietnam to deter the Viet Cong and later in Cambodia, whose shared border with Vietnam was also used as a supply route. The legacy of Agent Orange was severe health effects affecting millions of people and severe environmental damage. The extensive exposure and long-term contamination resulting in immediate and long-lasting harm to civilians illustrated how Cold War strategies often treated populations as secondary to technological and strategic imperatives.

Entire villages were obliterated, farmland left infertile, and over two million civilians displaced in Vietnam. Estimates of civilian deaths from the bombings range from 1.3 million to over 3 million. As communities suffered, anti-government sentiment surged internally. Many Cambodians came to see the United States and the US-backed Cambodian government as responsible for their suffering. The countryside, fragile from years of instability, collapsed under foreign bombardment, demonstrating the human cost of a deterrence-based strategy applied in conventional warfare.

In 1970, Sihanouk was overthrown in a coup led by General Lon Nol, who established a pro-Western regime. This furthered the country’s path toward civil war. The communist Khmer Rouge, led by Pol Pot, positioned itself as nationalist revolutionaries fighting against Western Imperialism, gaining widespread support from those displaced and devastated by US bombing. Radicalization transformed desperation into political extremism, showing how strategic violence intended to suppress communism, inadvertently fueling its rise.

By April 1975, after capturing the capital, Phnom Penh, the Khmer Rouge overthrew Lon Nol. A four-year campaign of terror ensued, which is known as the Cambodian Genocide. Academics, ethnic minorities, religious leaders, and anyone associated with the old regime were systematically murdered. About a quarter of Cambodia’s population died by execution, from forced labor, starvation, and disease. The genocide occurred within a broader context of ideological manipulation and Cold War geopolitics, showing how global strategic thinking can generate devastating local consequences.

Nuclear-era thinking ignored human costs

The US bombing campaign was an attempt to defeat communist forces. However, in reality, it achieved the opposite. The destruction failed to weaken the North Vietnamese, radicalize the local population, and enabled the Khmer Rouge rise to power. The long-term consequences of this strategy were dire, both for Cambodia and for the credibility of US foreign policy. The Cambodian genocide is a stark reminder of how foreign intervention may backfire with horrifying consequences. It also shows how nuclear fear was beginning to extend to all corners of the world. The reliance on conventional firepower produced devastation indistinguishable in human suffering from nuclear scenarios, impacting generations to come.

During this period, Cambodia endured one of the heaviest aerial bombardments in modern history. Although often discussed in political terms, the imprint of that campaign was physical — tons of high-explosive ordnance, incendiaries, and cluster munitions fell on rural provinces, cratering the landscape, destroying livelihoods, and leaving an unexploded ordnance hazard that persists. Estimates vary, but scholars cite roughly half a million tons of bombs dropped on Cambodian soil and destruction comparable to the heaviest bombing campaigns of World War II. The US military utilized both nuclear and conventional war strategies, demonstrating how Cold War logic prioritized deterrence and technological display over human cost.

The Cambodian case raises complex legal and ethical questions that continue to shape dynamics regarding the concentrated use of such weapons in populated areas. Principles of distinction and proportionality in international humanitarian law call for combatants to minimize harm to civilians and civilian objects. These principles were disregarded, conflicting with international law and the strategies of Cold War policymakers. Cambodia demonstrates how nuclear-era thinking justified extreme force, even at the expense of humanitarian obligations. Modern discussion about arms control and humanitarian constraints must be approached with attention not only to weapon lethality but also to the broader social and political consequences of advanced military technology.

The bombs over Cambodia did more than “destroy targets”; they left scars on people and land that painted once-peaceful village paths and homes. This underscores how nuclear-era strategy was measured not just by armaments, but by the fear, suffering, and societal disruption it produced. Cambodia presents a cautionary discourse on nuclear arms control, illustrating the need to prevent states from crossing the thin line between defensive security and excessive force within another territory. International humanitarian law calls for proportionality, civilian protection, and accountability, but these principles were ignored during the Vietnam War. Recognizing this historical mistake, policymakers must integrate humanitarian considerations with weapons regulation in the 21st century.

The shared memory of strategic logic of the nuclear age must be recalled as a turning point, prioritizing safety and security not only for governments but for all citizens. The history of an era dominated by the nuclear thinking era is measured not only in warheads but in the lives, communities, and landscapes devastated by the drive to dominate; Cambodia’s history serves as a stark reminder of this human cost.

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About the author

Serena Bush is currently pursuing an LL.M. in International Human Rights and the Protection of the Environment at Charles University Prague. From a young age, her interest has pertained to genocide studies. This passion has grown into a lasting commitment to advocacy, prevention, and the pursuit of advanced education. Dedicated to peace building, Serena has attended numerous conferences speaking about her Middle Eastern background in the US, Europe, and her home. For Serena, education exceeds a
credential and is a lifelong tool. She strongly believes it enables us to confront injustice, strengthen empathy, and empowers us to seek truth with clarity and courage.

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Photographs copyright-free from https://unsplash.com/s/photos/khmer-rouge