Of the many atrocities committed and the genocides performed throughout the 20th Century, few cases rival the stories that have come from of the Cambodian “killing fields”. Between 1970 and 1979, an estimated 1.2 – 2.2 million Cambodians were killed by the Khmer Rouge (Genocide). The barbaric nature of slaughter, the torture committed on innocent civilians, and the beliefs that fueled this genocide is a surprising combination of the accidents of history, ideological extremism, blundered US foreign policy, and clandestine US militarism. In reviewing the history of Cambodia, the horror of this mass-genocide appears to establish a universal and moral mandate on mankind to ensure that something like this will never take place again. An important question to ask is concerning how the United States may have failed to keep the killing fields from happening.

Today, college classrooms still discuss the killing fields to determine the ethical dilemmas of foreign interventionism. Questions seek to determine the ethical nature of a call-to-action, and it is becoming more consistently apparent that good questions are necessary to extract good answers. Today’s questions of an international moral ethic must necessarily root themselves in an international understanding of political, economic and social history, and within the social context of cultural diversity; otherwise, the wrong questions will be asked, and the solutions will only serve to fester in the wound of international tragedy and turmoil.

In the philosophies regarding international ethics are two prominent and competing political theories that fight for the international limelight of political policy. These theories are idealism and realism. From these theories, states have waged and deflected wars, established international courts and laws, and have seen the emergence of a new global community. These two philosophies have had an interesting courtship, as both have tried to take the lead in the dance of political power and policy; however, since it appears that it “takes two to tango”, we may assume that it takes both a realist and ideological philosophy to cover all the necessary grounds to make an appropriate policy.

Outline of Paper and Thesis

This paper is written in four sections. Each section is quite different in content from the next, but these seemingly unrelated sections are necessarily interrelated (as will be shown). The first section of this paper will address the short, but necessary, problems in the history of Cambodia that led to the travesties of the killing fields. The second section of the paper will give a short synopsis of idealism and realism in the 20th Century, and it will discuss various elements of these theories in matters pertaining to international ethics. The third section will address certain natural law theories of international politics concerning just war and interventionism, as proposed by St. Thomas Aquinas and Samuel von Pufendorf. We will use these philosophers to lay a foundation and ethic for moral action.

The pendulum of political policy swings between realism and idealism. When the harsh reality of power politics is too much to bear, then political policy returns to a more gentle and thoughtful sense of idealism. On the same token, when idealism has made the state too soft and complacent, then realism is eager to establish a common sense approach to political policy. Whereas, in the 20th Century, there were a small handful of followers after a type of ‘pragmatic-idealism’, the realist doctrine of power-politics gained the lead in the dance of political policy. It is reported that Mao Zedong once said that “Power comes from the barrel of a gun”; however, this paper will address an alternative theory of idealism in coping with the issues of international ethics. Finally, this paper will show that in its rejection of a moral idealism, an extreme American realism helped billow the fire of the communist revolution in Cambodia, and that moderate realism helped perpetuate the burning atrocities that were committed in the killing fields of Cambodia.

History of Cambodia and Conflicts to Solve

The last 100 years of history in Cambodia is replete with European colonialism and domestic struggles for independence. France formally colonized Cambodia in 1863, and it was a protectorate of Cambodia until 1953 (History). The French had assumed nearly all but ceremonial powers from the Cambodian monarchy, until Norodom Sihanouk came to power in 1941. France was reluctant to give up influence of Cambodia; however, coupled with the national stresses caused by the Japanese occupation during World War II and Sihanouk’s work to free Cambodia from any outside influences, Cambodia gained its independence from France in 1949. After taking control of Cambodia, Sihanouk took advantage of the French-Indochinese War, and he gained military control of the country. He later abdicated military power to his own father, but he remained in control of the government until 1960 when he became the chief of state without ever returning to his throne (Cambodia).

Sihanouk took an expected anti-western approach to politics. After nearly three quarters of a century under western colonization, Cambodia was in no hurry to align itself with its perceived foreign aggressors. As such, through the 1960’s, Cambodia took a strict neutral stance to all parties involved in America’s Vietnam War. However, during this time, North Vietnam used parts of Cambodia (along the Ho Chi Minh Trail) as a place of refuge from American forces, and a communist group in Cambodia, called the Khmer Rouge, became increasingly troublesome to the neutral Sihanouk.

In addition to perceived American military aggression, the Khmer Rouge charged the United States for overthrowing Sihanouk from power. In 1970, Lon Nol took control of Phnom Penh through a military coup while Sihanouk was in China. The United States backed Sihanouk’s overthrow because of Lon Nol’s adamant stance against Communism – even though it was known that Lon Nol governed violently with an iron fist. This perceived use of naked aggression gave the Khmer Rouge more fuel for the fire, as the Khmer easily recruited country peasants to their war against the West for its continued injection in the coutnry’s affairs; after all, what loyal citizen would not join a locally established resistance group to fight against the same perceived colonial-type powers that were just rejected nearly two decades before (Talbott)?

Khmer Rouge

While the Khmer Rouge is often touted as a group of ideologically driven Communist extremists, current evidence shows that this is probably not as true as initially reported. While many leaders of the Khmer Rouge were ideologically driven, most of the initial sparks and recruiting power came from uneducated peasant workers who experienced a collateral effect from the Vietnam War (Johnson 12-3). This is to say that the individual recruiting efforts were anti-American, as opposed to pro-Communist. The borders of the Vietnam War were not as neatly drawn as we like to think they were. After months of American airstrikes and carpet bombing of the Cambodian portion of the Ho Chi Minh Trail (in search of hiding Viet Cong), innocent Cambodian casualties started adding up. It did not take much effort for the Khmer’s to convert the poor and uneducated people to a cause that was strictly anti-Western. The political hydra was at work – for every Viet Cong communist the Americans would kill along the Ho Chi Minh Trail in Cambodia, dozens of Cambodian peasants would take up the banner of Communism with the Khmer Rouge.

Pol Pot, the leader of the Khmer Rouge, was a French educated Cambodian who had belonged to the French Communist Party (PCF). In 1975, Pol Pot’s Khmers finally gained control of Phnom Penh and ousted Lon Nol from power. During this time, Pol Pot sought to return the people to a purely agrarian society, and tried to throw off all forms of westernization that had seeped into Cambodian life. From 1975 – 1979, the Khmer Rouge killed millions of Cambodians for being too westernized.

The Killing, Torture, and Social Programming

The Khmer Rouge killed every Cambodian that was perceived to have received western training or education. Cambodians who spoke English, wore glasses, or who had any advanced education were perceived as ‘westernized’ and were promptly killed. Often, the prisoners were tortured, raped, or dismembered before being savagely slaughtered. In his famous auto-biography, Survival of the Killing Fields, Haing Ngor spoke of his personal experience of being crucified over a bed of hot coals, and he spoke of the searing pain of his blistered feet as the blisters burst open when he was finally cut down from the cross and was able to walk (Ngor 262-67).

Children were taken from their families and programmed to become child-soldiers for the Khmer Rouge; furthermore, in many cases child soldiers were programmed to kill their own family members (Jackson). They were taught to defend the Communist ideal and to give their life for it.

Evaluation of International Realism and Idealism in the 20th Century

It is difficult to determine which theory came first – idealism or realism? There is no doubt the troubled relationship shared between these two theories, but it is important to give a short synopsis of both theories so that we can determine how they apply to an ethical analysis of the killing fields.


Idealism, in part, signifies the natural right and natural law theories as derived from an Aristotelian concept of ‘the good’ that evolved through Aquinas, and then later through the philosophers of the Enlightenment. Idealism, in many cases, posits man’s innate goodness and moral imperative. It is in idealism that man questions whether there is a moral and universal absolute, or whether our moral imperative changes according to social, economic, and natural pressures.

There is an important argument in idealism that questions whether the same rules that apply in a moral relationship between individuals as also applies to the moral relationship between states. There is no definitive answer to this question, but the arguments on either side are compelling. While John Westlake argues that “The duties and rights of states are nothing more than the duties and rights of the men who compose them” (Westlake 78), Michael Walzer argues that

State rights are not constituted through a series of transfers from individual men and women to the sovereign or through a series of exchanges among individuals… The moral standing of any particular state depends upon the reality of the common life it protects and the extent to which the sacrifices required by that protection are willingly accepted and thought worthwhile. If no common life exists, or if the state doesn’t defend the common life that does exist, its own defense may have no moral justification (Walzer 54).

These two quotes apply a different concept and source of morality for both the individual and the state. While Westlake argues that the state can only have as many duties and rights as the people who compose the state, Walzer argues that the moral standing of the state is dependent on the nature of common life that the state protects. Every state, says the idealist, has valid ideas that deserve to be heard and examined thoroughly.


In contrast to idealism’s moral imperative, realism makes no such absolute claim to any such imperative. This is not to say that realism rejects every moral virtue; however, as idealism’s primary focus is to uphold the moral virtue itself (for the moral virtue’s sake), the realist’s primary focus is to use a moral imperative to advance the state’s power (for the power’s sake). Realism is only concerned about a few things, but it calls for us to address and see things for as they are (and not to worry about how things ought to be). While idealism argues that states have a moral imperative, realism claims that states act in their own self-interest and power.

In his book The Twenty Years Crisis, E.H. Carr argues that a Utopian idealism must eventually give way to a practical form of realism (Carr 71). Carr expresses his concern that idealism alone is not sufficient to address the growing needs and situations of international politics; furthermore, Carr argues that “in both physical and political sciences, the point is soon reached where the individual stage of wishing must be succeeded by a stage of hard and ruthless analysis” (Carr9). This is to say that idealism must give way to the realist’s “ruthless analysis” of the world. That said, Carr is no fan of the cold and stark reality that extreme realists had brought to the table of political policy, but Carr argued that we should advance a more moderate form of realism that addresses the relative morals of society when engaging in power politics (Carr 19). This form of moderate realism is certainly at play in today’s engagement of political policy.

Idealists in Action: Thomas Aquinas and Samuel von Pufendorf

While the venerable St. Thomas Aquinas receives praise for his involvement in perpetuating natural law and the Aristotelian traditions, Samuel von Pufendorf has shared relatively little attention in comparison. In determining the basic understanding of these philosopher’s arguments concerning international conflict and war, it is difficult to ascertain a perfect correlation between the philosophy and the events of the Cambodian killing fields. To find the natural law, we must first discover the principle wherein these philosophers spoke; afterward, we will try to more accurately use their philosophy and ideas to determine an appropriate course of ethical action.


For Aquinas, any act of war or aggression, even if it is by nature an intervention, must be iusta causa (i.e. there must be a ‘just cause’). No just cause is given unless those we attack are guilty of some wrong which they refuse or fail to rectify (ST II-II q. 40 a. IC). Aquinas’s discussion of just war focuses primarily the decision to initiate war; that is, for Aquinas, there is no necessary causa in self-defense (Finnis 285). Aquinas stipulates that legitimate authority, just cause, and proper intentions are necessary in declaring any war.

What Aquinas does exclude from this theory of war is the “take no prisoners” policies “or any other policies making the killing of enemies and objective—say, to terrorize other soldiers, or put other psychological pressures on enemy leaders” (Finnis 287).Furthermore, as a matter of natural law, Aquinas universally rejects the “killing of innocents” (ST II-II q. 65. a. 6).


Unlike Aquinas, Pufendorf spends a good amount of time discussing individual and state wars. For Pufendorf, the reasons for a just war are

to preserve and protect ourselves and our things against others who are trying to hurt us or to take away or destroy these things; to assert ourselves when others, by whom we are owed anything from a perfect right, refuse to furnish it of themselves; and, finally, to obtain reparation for harms by whose infliction we have been injured, and to wrest from one who has previously hurt us a guarantee that he will not attack us in the future (Pufendorf 258).

We must always maintain that our wars, especially the offensive wars, have a strict, clear, and definable cause. We should always use these three rules to determine a rational response, as opposed to “flying in to war” (Pufendorf 258).

While there are just reasons for entering war, Pufendorf addresses certain unjust reasons as well. In hearkening back to Grotius’s work,On the Law of War and Peace, Pufendorf argues that fear of our neighbor’s strength and power is no justification for war. While we are allowed to defend and equip ourselves in times when we feel threatened, we have no moral authority to lash out in these cases.

For Pufendorf, the theory of proportionality is not as evolved as it is in the 20th and 21st Century. Pufendorf argues that it is not “always unjust to repay a greater evil for a smaller”, and that once someone has attacked me “by declaring himself my enemy grants me the license to exert unlimited force against him, or as much as seems appropriate to me… The end of war, be it offensive or defensive, cannot be obtained with this license” (Pufendorf 259).

In accordance with his general principle of war, that peace is the only justifiable end for war, Pufendorf argues for a time when waging war in the defense of another is appropriate and justifiable. This type of warfare, however, is only justifiable when those we are protecting are bound to us by treaty or are “subjects” of the state. Pufendorf gave several natural limits on helping those who we are in treaty with, because no state should be at the military whim of another state’s disposition to wage war (Pufendorf 260).

The Realist Problem

It is too overly-simplistic to say that the United States was the sole or primary catalyst for the Khmer Rouge’s successful recruiting and genocide in the late 1970’s Cambodia. This does not, however, dismiss the United States from certain accountability. During the late 1960’s, the United States bombarded the Ho Chi Minh Trail in Cambodia and blanketed the regions with bombs, missiles, and other bombardments during, and after, the Vietnam War. This heavily realist approach helped spark Cambodian resentment against US military involvement along the Ho Chi Minh Trail; furthermore, the US military’s involvement in overthrowing Sihanouk through a military coup did not settle well with the residual of anti-western feelings that Cambodians still held after three-quarters of a century under French colonialism. If the United States’ proactive realist policies in Cambodia were not the sole catalyst for helping the Khmer Rouge to come to power, these blundered policies certainly helped the Khmers to find a foothold.

In addition, once Pol Pot’s Khmer Rouge had ousted Lon Nol and began the genocide of its own people in 1975, the United States was quick to dismiss any charges concerning its tampering in Cambodia’s affairs (either concerning the bombings or concerning the assisted coup); furthermore, the United States sought to distance itself from Cambodia, because it could not afford for the American people to suffer any more wartime discontent than what residual suffering the people already endured from the unpopular Vietnam War. This moderate-realist approach only furthered to cement the United States’ hypocritical and aggressive reputation in South East Asia.

The Idealist Solution


As already addressed, Aquinas posits that legitimate authorityjust cause, and righteous intent are necessary to wage any justifiable war. In his argument for just cause, Aquinas quotes Augustine who says that “A just war is customarily defined as one which avenges injuries” (Quaestiones in Heptateuchum 4:10). However, a mere justification for avenged injuries is not enough for Aquinas to argue for interventionism. The just war is fought with a righteous intent and decreed by a legitimate authority, but beyond this we are left speculating how, when, and why our personal moral imperative transitions to state action. Aquinas gives no expressed principle for why the state cannot assume a moral imperative for protecting other states. If we desperately desire to find such a theory in Aquinas, it is necessary to create a hybrid-theory between Aquinas and another philosopher – but this does not guarantee our desired outcome.

Pufendorf, unlike Aquinas, does give us a stated principle for state interventionism. Pufendorf argues that the state can protect a third party, if the third party is subjected to the state or if the third party is in treaty with the state. While his premises for just war vary from Aquinas’s, Pufendorf does assert a rather Aquinian concept that peace is the ultimate end of war. This said, there is still no determinable principle for us to gauge a moral imperative in the situation concerning the killing fields of Cambodia. While possible US military action may be somewhat justified in an Aquinian interpretation a righteous intent, no principle of Aquinas addresses the moral imperative of the United States after its perceived long standing abuses in Cambodia (the bombing of the Ho Chi Minh Trail and the overthrow of Sihanouk). Furthermore, Pufendorf’s justification for interventionism does not apply to the Cambodian situation. Cambodia is neither subjected to the United States, nor was the Khmer run Cambodia in treaty with the United States.

The Answer and Conclusion

During the Vietnam War, supposed anti-communist idealisms hid the extreme and moderate realist practices of US militarism. These realist practices denied the fundamental principle of just war as addressed by Thomas Aquinas and Samuel von Pufendorf. Cambodia was not our intended target, and thousands of innocent Cambodians lost their lives due to the overstretched arm of US military involvement from Vietnam.

In this particular situation, the United States violated the just war theories of Aquinas and Pufendorf. According to Aquinas’s argument, the United States had no injuries to avenge against the Sihanouk led Cambodian government (thus negating any US claim to just cause), nor was there a specified ‘righteous intent’. According to Pufendorf, the Sihanouk led Cambodia was not trying to attack or take control of America; in fact, Sihanouk proclaimed a neutral policy. There are some reports that Sihanouk was sympathetic to Communist doctrines, but there is little-to-no evidence that shows he acted against the United States in supporting North Vietnam. Furthermore, Cambodia did not default on any debts or obligations to the United States, nor did the United States have any claim to reparation from Cambodian mistreatment and injuries.

In these cases, the United States stands accountable for its actions that spurred a violent revolution and genocide. The United States is not inherently accountable for every life destroyed or person tortured in the killing fields, but it is accountable for a blundered foreign policy that denied a natural principle and gave rise and unintended sympathy to a violent ideology.

What is our moral imperative concerning genocide? The realist approach taken by the United States, in this particular instance, proved incompatible to address the real problems present in the ideological movement in Cambodia. It has been said that ideas are bullet-proof, and it takes more than guns and missiles to destroy a thought. By the time the killing fields started, the United States had already failed in its moral imperative.

Works Cited

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“Cambodia.” Infoplease. Web. 8 Apr. 2010. .

Carr, Edward Hallett, and Michael Cox. The Twenty Years’ Crisis, 1919-1939: an Introduction to the Study of International Relations. Houndmills, Basingstoke, Hampshire: Palgrave, 2001. Print.

Finnis, John. Aquinas : Moral, Political, and Legal Theory. Oxford [England]: Oxford UP, 1998. Print.

“Genocide – Cambodia.” Peace Pledge Union. Web. 09 Apr. 2010. .

Johnson, Chalmers A. Blowback: the Costs and Consequences of American Empire. New York: Henry Holt, 2004. Print.

Pufendorf, Samuel, and Craig L. Carr. The Political Writings of Samuel Pufendorf. New York: Oxford UP, 1994. Print.

Talbott, Strobe. “America Abroad: Defanging the Beast.” Time. 6 Feb. 1989. Web. 09 Apr. 2010. .

Walzer, Michael. Just and Unjust Wars: a Moral Argument with Historical Illustrations. New York: Basic, 2006. Print.

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