Civil War: Cambodia (1970-1975 and 1979-1991)

Dong-Yoon Lee. Civil Wars of the World: Major Conflicts since World War II. Editor: Karl DeRouen Jr. & Uk Heo. Volume 1, ABC-CLIO, 2007.


Cambodia, one of the oldest states in Southeast Asia, has undergone many transformations, from the ancient Angkor Empire to today’s Kingdom of Cambodia. Since the nineteenth century, it has been subject to the influence of many other countries, including France, Japan, China, the Soviet Union, the United States, and neighboring Vietnam and Thailand. The population is largely rural, an ethnically homogeneous people most of whom are Buddhists and whose principal language is Khmer. Cambodia’s two civil wars, the first from 1970 to 1975 and the second from 1979 to 1991, were inextricably bound up with international Cold War politics and the Vietnam War. Despite the Paris Peace Agreement of 1991, which ended the last civil war, Cambodia is not completely at peace today.

Country Background

Cambodia’s long history has not provided a shield against political turmoil. From the ninth to the thirteenth centuries, Cambodia’s Angkor Empire ruled over much of the Southeast Asian mainland. It left historical remains that are among the wonders of the world and evidence a highly developed civilization. From the fourteenth century, Cambodia began to contract, squeezed by Thailand on one side and Vietnam on the other. From the seventeenth century to the eighteenth, Cambodia degenerated into a tribute country subject to intervention by Thailand and Vietnam in its domestic affairs, a period known as Cambodia’s “Dark Age.” This period ended when Cambodia was made a French protectorate in 1863 and became a part of French Indochina. During World War II, Cambodia was occupied by the Japanese. After World War II, Cambodia remained a French colony until its independence in 1953 (CIA 2005; Peou 2001, 36).

Cambodia’s independence did not guarantee the building of a peaceful and stable state of Khmer people. Cambodia’s ideological conflicts and civil wars, its “vortex of politics,” inflicted poverty, death, and the fear of war on countless numbers of people for a long time. The Kingdom of Cambodia, ruled by Prince Norodom Sihanouk, was established in 1953 and lasted until 1970, although political chaos continued as domestic ideological conflicts increased, as did threats posed by the communization of the Indochina peninsula—particularly the Vietnam War. In 1970, the Khmer Republic, an extreme right-wing, anticommunist regime, was established following a coup d’état led by General Lon Nol. The antigovernment protests and guerrilla warfare between the Communist Khmer Rouge and the supporters of the deposed Sihanouk continued until 1975. With the end of the Vietnam War in 1975, the Communist revolution led by the Khmer Rouge was successful, and Cambodia became Democratic Kampuchea. Between 1975 and 1979, however, under the leadership of Pol Pot, the level of internal political conflict and bloodshed increased to such a level that Cambodia became known as the “Killing Field.” The massacres produced a large number of refugees. Working from Hanoi, pro-Vietnamese powers in turn expelled the Khmer Rouge by sending Vietnamese troops to attack Cambodia and established another Communist government, the People’s Republic of Kampuchea (PRK), and leaving a Vietnamese military advisory group to supervise Cambodia’s domestic affairs. When the Vietnamese troops completely withdrew from Cambodian territory in 1989 in response to steadily increasing international pressure to conclude Cambodia’s civil war, then-prime minister Hun Sen changed the country’s name to the State of Cambodia (SOC) and concluded a peace agreement with the antigovernment powers.

After the country’s existence as Prince Sihanouk’s Kingdom of Cambodia in 1953, through the signing of the Paris Peace Agreement in 1991 and the democratic elections mandated by the United Nations in 1993, and finally into Cambodia’s reincarnation as the State of Cambodia, the nation experienced political instability and transitional turmoil in both its domestic and its international affairs. In particular, the Communist revolutionary movement, which spread rapidly after 1960, became a civil war as a result of Lon Nol’s coup d’état and the establishment of the extreme right-wing, anticommunist Khmer Republic. Cambodia was eventually communized by the Khmer Rouge in 1975; the Khmer Rouge were expelled and the Khmer Republic replaced by the PRK. Despite this, civil war continued until the Paris Peace Agreement was signed in 1991, owing to prolonged physical clashes and military conflicts between the PRK government, remnants of the former Khmer Republic government, and Sihanouk loyalists.

Conflict Background

To understand the background of the two Cambodian civil wars, 1970-1975 and 1979-1991, it is necessary to comprehend Cambodia’s domestic and international circumstances at the time of independence in 1953. The Indochina peninsula, which had been under the protection and colonial rule of France since the end of the nineteenth century, had been an arena of perpetual struggle among the world powers. During World War II, Cambodia was occupied by the Japanese. After the war ended in 1945, King Norodom Sihanouk demanded Cambodia’s independence from France. In 1953, Cambodia achieved independence, and King Sihanouk, a widely respected leader, established the Kingdom of Cambodia.

Sihanouk, who converted Cambodia’s form of government to a constitutional monarchy after independence, handed over royal authority to his father, Norodom Suramarit, in early 1955 and attained absolute power by successfully winning the general election. He then established the leading political party, Sangkum (Sangkum Reastr Niyum), and maintained a comparatively stable, authoritarian rule until the mid-1960s. Sihanouk’s greatest political goals were Cambodian independence and a stable reign, and he sought various diplomatic policies that would influence international politics and provide a secure regional environment to fulfill his goal. The surrounding environment of the Indochina peninsula, which had undergone rapid change since the end of the 1950s, in fact caused Sihanouk’s basic diplomatic policies to change; political changes in Vietnam were particularly important factors. Sihanouk’s diplomatic position was initially pro-American, and he accepted American support in the early stages of state building after independence in 1953; but he subsequently became a neutralist to get out from under pressure from the superpowers (America and China) when ideological conflicts deepened in Indochina later in the 1950s. In the 1960s, he attempted an ideological transition to collaboration against the Communists when the threats against Communism increased.

There is no doubt that the international divisions and confrontations caused by the Cold War affected Cambodia’s diplomatic policies and domestic politics (Peou 2000). In the earlier stages of independent statehood, Sihanouk selected pro-American diplomatic policies to oppose threats from surrounding countries such as China and Vietnam. However, Sihanouk diplomatically approached China and Vietnam while fundamentally deciding to remain neutral because (1) interference in Cambodia’s domestic politics by South Vietnam and Thailand accompanied U.S. support, (2) potential threats were increasing, and (3) Khmer Serai, the rightist organization supported by the United States, was gradually expanding its activities. Nevertheless, improvement of relations with Communist countries eventually led to the severance of diplomatic relations with the United States when the Vietnamese war reached its climax.

Sihanouk’s attempt to reach a strategic balance, however, was challenged by the following factors. First, Cambodian neutrality was damaged by the presence of the North Vietnamese and the Viet Cong’s base in Cambodia. Second, it was also plagued by the use of Kampong Saom (then Sihanoukville) by the Communists as a supply port for Communist forces, as well as the intelligence gathering activities on the parts of both South Vietnam and the United States. By 1966, Sihanouk had allied himself secretly with the North Vietnamese, a decision (probably impossible to avoid) that was a major reason for his deposition four years later. Under the terms of the alliance, the North Vietnamese stationed troops in Cambodian territory and received arms and supplies from North Vietnam and China via the port of Sihanoukville in Cambodia (Chandler 1996, 194).

Frequent changes in Cambodia’s diplomatic policies caused domestic political disorder. In fact, the Sihanouk administration was most interested in the movements of Cambodian Communists, the Khmer Rouge. With the threat of Communizing Indochina on the increase since the mid-1960s, Sihanouk attempted to compromise with the Communists. After the dismissal of the Indochina Communist Party (ICP) in 1951, the Khmer Rouge lost its power for some time, as demonstrated by the movement of the Hanoi Khmer to northern Vietnam. However, the Khmer Rouge was re-established by young Communists such as Ieng Sary, Khieu Samphan, Hou Yuon, and Saloth Sar (Pol Pot). They equipped new battle lines while maintaining an independent relationship with the Indochina Communist Party and organized an anti-Sihanouk guerrilla movement in the late 1960s. The leftist powers began to expand their activity to consolidate the communist line, starting with the 1966 election; at the same time, the rightist factions began to back away from Sihanouk to restrain his procommunist policy. In 1966, Communists Hou Yuon, Khieu Samphan, and Hu Nim, who were elected representatives, were given ministerial posts; but they remained honest despite this patronage. They surrendered their posts in 1967 and 1968 and escaped to the jungle region when their lives were threatened by the prince’s men and by right-wing government factions.

From the mid-1960s, the Sihanouk administration faced domestic political crises caused by various factors, such as the failure of socialistic economic policy pursued by Sihanouk, isolation from the Western countries, resistance of rightist powers in the country followed by the relationship with the Vietnamese communists, and the activities of supporters of Communist revolution. In early April 1967, Samlaut and Batdambang, two provinces known for the presence of big landowners and economic inequality, were plagued by insurrections. More than 200 local people, some bearing anti-American banners, attacked Cambodian army posts near Samlaut. The Communist party leaders in the faraway northeast did not know when the attack was going to occur, but undoubtedly the local radicals, exasperated by the government’s behavior, encouraged the people to revolt (Chandler 1992, 81). The government was unable to pacify the insurgency completely. It spread from Batdambang to the south and southwest and to the central provinces. The areas affected were Pouthisat (Pursat), Kompong Chang, Kampong Cham, Kampong Spoe (Kompong Speu), Kampot, and Kampong Thum. Eleven provinces were reportedly affected by the insurgency by the end of 1968. The Kampuchea Communist Party (KCP) almost completely dominated the Khmer Loeu regions of Mondol Kiri (Mondolkiri) Province and Rotanokiri Province until the end of the decade.

The Revolutionary Army of Kampuchea (RAK) was set up by the Communists in January 1968. Although Sihanouk was still in power, the RAK did not get much support from the North Vietnamese, the Viet Cong, or the Chinese. On the other hand, because Sihanouk’s Cambodia ontrolled some parts of supply lines vital to North Vietnam for its Viet Cong bases, North Vietnam did not want to sour its relationship with Cambodia. In addition, weapons supplied to Sihanouk by Beijing and Moscow were used to suppress the insurgents. Pol Pot and other Khmer Rouge leaders became convinced that other Communist countries did not care much about the Communist struggle in Cambodia from 1967 to 1969.

Sources: Marshall and Jaggers 2002.
War: Khmer Republic government vs. FUNK (1970-1975)
PRK government vs. CGDK (1979-1991)
Date: March 1970-April 1975
December 1978-October 1991
Casualties: At least 200,000 (1970-1975), estimated
300,000 (1979-1991), estimated
Regime type prior to war: -7 (Lon Nol’s Khmer Republic in 1970; republican authoritarianism; Polity II variable in Polity IV data, ranging from -10 to 10)
-7 (the Khmer Rouge’s Democratic Kampuchea in 1979; revolutionary totalitarianism)
Regime type after war: -7 (continued since the Democratic Kampuchea government) 2 (since 1998)
GDP/capita year war began: Estimated US $130 (an estimate in 1970)
Estimated US $130 (an estimate in 1979)
GDP/capita 5 years after war: Estimated US $130 (in 1980)
Estimated US $300 (in 1996)
Insurgents: FUNK (1970-1975)
CGDK (1979-1991)
Issue: Ideological struggle for control of central government
Rebel funding: Foreign aid (USA, USSR, China, Vietnam, Thailand, etc.)
Role of geography: Rebels hid in rain forest and mountains.
Role of resources: Not known
Immediate outcome: Victory of the Khmer Rouge; establishment of the Democratic Kampuchea
government in 1975
Treaty facilitated by UN in 1991; democratic general election in 1993
Outcome after 5 years: Continuous civil war and dissolution; collapse of the Democratic Kampuchea
and establishment of the People’s Republic of Kampuchea in 1979
Provisional peace maintenance and establishing the coalition government since 1991
Role of UN: No active role from 1970 to 1975
Facilitated peace talks from 1979 to 1991; implemented UNTAC in 1992.
Role of regional organization: ASEAN active since 1967, but no successful result
Refugees: Roughly 360,000 (1970-1975)
600,000 (1979-1991)
Prospects for peace: Provisional peace since democratic election by UNTAC in 1993
Potential for conflict between CPP and FUNCINPEC persists
Table 1: Civil War in Cambodia

The Insurgents: Coup D’état, The Communist Revolution, And Pol Pot’s Regime (1970-1979)

It is not easy to identify precisely the rebels in the Cambodian civil war that began in 1970. The Communist forces, which began to gradually strengthen the Communist revolutionary movement against the Sihanouk administration from the late 1960s on, commenced its rebellion when the rightist military coup d’état led by General Lon Nol occurred in March 1970. The Communist revolutionary movement initially spread in the form of protests or regional rebellions with the Khmer Rouge at the center. However, the civil war entered a new phase that involved ordinary combat and guerrilla warfare when Sihanouk, who was deposed by General Lon Nol in 1970, proclaimed the coup a military rebellion and made an alliance with the Khmer Rouge. The alliance of the royal powers (Sihanouk’s supporters, leftists, and Communists) and Khmer Rouge combined to form the National United Front of Kampuchea (FUNK: Front Uni National de Kampuchea) and announced an official attack against the Khmer Republic administration established by Lon Nol.

After its formation in March 1970, FUNK claimed to stand for the alliance of the entire Khmer people, both outside and inside the nation, including the Khmer Rouge, and was followed by the announcement of the establishment of the Royal Government of National Union of Kampuchea (GRUNK: Government Royal d’Union Nationale de Kampuchea) in May. The Khmer National Armed Forces (FANK: Forces Armées Nationales Khmères), a military arm of the GRUNK that opposed the North Vietnamese and the Viet Cong at the beginning, was reinvigorated and renamed the Cambodian People’s National Liberation Armed Forces (CPNLAF). Although Sihanouk visited once-liberated areas of Cambodia, including the Angkor Wat area, he and his followers stayed mostly in Beijing, whereas the Khmer Rouge commanded the insurgency inside the country. Increasingly, Sihanouk lost his grip on power and became a passive figurehead in the coalition. Even those who supported Sihanouk in Cambodia faced a death threat by the Khmer Rouge. Furthermore, Sihanouk himself, when he appeared in public to espouse the cause of GRUNK, was contemptuously challenged by Ieng Sary and Khieu Samphan.

Consequently, the Khmer Rouge controlled the entire combat power of the GRUNK, as well as the FANK, which was founded with approximately 3,000 people in the early 1970s and had grown to 40,000 people by 1973. At that time, Communist power in Cambodia was divided into two camps: the Pol Pot camp, which was active mainly in the northern and northeast and took an extreme anti-Vietnamese stance; and a pro-Vietnamese group called Hanoi Khmer, which had bases in the east and the southwest. The Hanoi Khmer obtained control of agricultural areas according to the guerrilla strategy of Mao Zedong and closed the net encircling Phnom Pen by disrupting the defenses of the government troops. The political marriage between Sihanouk and the Khmer Rouge was a result of sheer political calculation. Peasants, as loyal followers of the monarchy, supported the FUNK cause. It came as no surprise, then, when Lon Nol abolished monarchy and renamed the country the Khmer Republic on October 9, 1970, that the popularity of the Sihanouk-Khmer Rouge coalition soared, even though ordinary peasants were worried about the consequences for Cambodia without its monarch. The number of government troops of the Khmer Republic grew from 35,000 in 1970 to 200,000 two years later, receiving various supports from America, Thailand, and South Vietnam. However, the government forces were internally corrupt and became weaker after they gradually lost the district bridgeheads despite earlier success in suppressing the rebels.


The two warring factions were by no means equal, and not just in terms of their numbers. Many urban young people voluntarily joined FANK within a few months of the coup. The Khmer Republican government outnumbered its enemy throughout its five years in power, but lacked training and leadership. As its numbers suddenly soared, the government was overextended. Because of the pressures of tactical operations and the need to supplement combat casualties, the FANK was unable to provide needed training for its members. Despite the bravery of some soldiers and government units, most of the leaders were corrupt and incompetent. They had to face what were arguably the best infantries at the time, the North Vietnamese and the Viet Cong. In the latter half of 1971, the Chenla II strategy of the Khmer Republic government troops, which was intended to mop up the antigovernment powers, failed; student protests intensified in 1972, overthrowing the corrupt Lon Nol administration and his despotic government. When Lon Nol’s Khmer Republic was founded, more than half of Cambodian territory had already been taken by North Vietnamese troops and Khmer Rouge guerrillas, and these “liberated areas” were increasing, particularly in the agricultural and mountainous areas (Kamm 1998, 87). This condition rapidly changed when the confidential agreement between Vietnam and the United States was reached in 1973, and withdrawal of American troops from the Indochina peninsula began. In June 1974, as Communist-led student riots spread across the nation, allied with teachers and laborers, the Khmer Republic administration was hard pressed to maintain the regime. The Khmer Rouge was winning the control of the Mekong River; by the end of 1974, they had blocked off all land routes, and Phnom Penh was isolated (Becker 1998, 17).

Causes of the War

The Cambodian civil war of 1970-1975 can be understood as having strong implications for the Communist revolution, which was an ideological conflict based on an international Cold War system that also influenced Cambodian domestic politics. Nevertheless, political conflict and armed clashes during Cambodia’s domestic conflicts resulted in the continuation and spread of the civil war. In 1970, few minorities inhabited this linguistically and culturally homogeneous land. In prerevolutionary Cambodia, 85 to 95 percent of the inhabitants spoke Khmer and followed the Buddha’s teachings. It was an overwhelmingly rural economy and ethnically quite homogeneous. And Cambodia was overwhelmingly Theravada Buddhist, whereas Chinese and Vietnamese are usually Mahayana Buddhists (Martin 1994, 1; Kiernan 2002, 5-6). Despite such similarities, ideological conflicts and confrontations caused by the international Cold War, and the threats to the regional security of Southeast Asia posed by the Vietnamese War, drove Cambodia into a more hazardous civil war.

The first Cambodian civil war was triggered by Lon Nol’s coup d’état in 1970, which toppled Sihanouk and drew Cambodia into a wider conflict. Communism had been spreading steadily since the late 1960s, and demonstration and rebellions were occurring in every region. Nonetheless, after the coup in 1970, most people in agricultural area supported Sihanouk, not Lon Nol; the regional conflict developed into a national one when Sihanouk made an alliance with the Khmer Rouge, the leaders of the Communist revolution. Backed by centuries of tradition, Prince Sihanouk continued to influence the social fabric of Cambodia, which increasingly resulted in large tracts of Cambodian territory falling under the administration of Cambodian rebels in the so-called liberated zone (Ayres 2000, 80). A large number of middle-class and educated Khmers in urban area were tired of Sihanouk and hoped for a change of leadership; nevertheless, most of the rural population still supported Sihanouk. Right after the coup, the prince, who stayed in Beijing, appealed to his people to resist the coup. Pro-Sihanouk riots broke out almost immediately in the eastern part of the country (Chandler 1996, 205).


The ideological component of the Cambodian civil war had been strengthened by the strong anticommunist policies of the Lon Nol administration and the involvement of the Vietnam War. When Sihanouk fell from power, North Vietnam and the Viet Cong were afraid of a prospective pro-Western regime in Cambodia, which might allow a U.S. military base in Cambodia. To avoid this, North Vietnam and the Viet Cong moved forces deeper into Cambodia, and a new military headquarters was set up in Kracheh (Kratié). South Vietnam and the United States jointly launched a multipronged attack in Cambodia to destroy the Central Office for South Vietnam, the headquarters of North Vietnamese and Viet Cong combat operations.

Duration Tactics

The attack destroyed extensive logistical installations and large amounts of supplies. Nevertheless, according to a report disclosed later from the United States Military Assistance Command Vietnam, a large amount of material had already been moved deep into Cambodia to avoid the attack. The North Vietnamese army spied on the Khmer Republic’s government forces, and three months after the coup, the North Vietnamese army and the Cambodian People’s National Liberation Armed Forces had wiped out FANK from the third of the entire northeastern of the country. After sweeping out the government forces, they focused on the local insurgents. The Khmer Rouge established “liberated areas” in the south and southwest, where they governed themselves independently of the Vietnamese.

External Military Intervention

Lightning attacks on and bombardment by the U.S. Army and the South Vietnamese troops in Cambodia during this process stimulated the Cambodians’ national sentiment and became the main cause of Cambodia’s involvement in the Communist revolution of the Khmer Rouge (Chandler 1998, 211). The United States, with no previous agreement with or warning to the Khmer Republic administration, dispatched 31,000 U.S. armed forces and 43,000 South Vietnamese armed forces into Cambodian territory and commenced massive bombardments. This strategy, which was approved by President Richard Nixon, was initially to attack the military bases of the North Vietnamese who had secret movements within Cambodian territory; but to this was added physical damage to the Cambodian people, creating as many as 130,000 refugees during the bombardments. Between 1970 and 1973, U.S. air forces carried out 2,875 decisive bombing attacks; nearly 450,000 tons of bombs were dropped in Cambodian territory— 50 percent more than were dropped on Japan during World War II (Becker 1998, 17; Kiernan 2002, 19).

Conflict Management Efforts

International society gave no help to end the Cambodian civil war between 1970 and 1975. On the contrary, the Cold War system of international politics was the fundamental cause of the Cambodian civil war: the extreme conflicts and confrontations between the capitalist powers (with the Western powers in the center) and the socialist powers (the Soviet Union and China) encroaching on the Indochina peninsula. Major Western countries such as the United States, and countries belonging to the Association of Southeast Asian Nations (ASEAN), such as Thailand and the Philippines, supported the Khmer Republic administration; whereas China, the Soviet Union, and Vietnam supported the Communist powers in Cambodia and the rebellion movements that followed after them. Threats of communization of the Indochina peninsula, initiated by the Vietnam War, accelerated ideological conflicts and civil war within Cambodia; and the countries surrounding Cambodia and the international powers supported different political groups in Cambodia in pursuit of their own interests.

When the United States withdrew its troops from the Indochina peninsula according to the 1973 confidential agreement between the United States and Vietnam, conditions in Cambodia also changed rapidly. The Khmer Republic lost more than 80 percent of the Cambodian territory to the Communist powers—the North Vietnamese, the Viet Cong, and the Khmer Rouge—and was deprived of a basis of support. Between that time and 1974, the population of the capital city, Phnom Penh, rapidly increased from 600,000 to 2,000,000 from the influx of refugees who fled their hometowns and flocked to the capital to avoid the U.S. attack and the Communist forces. Serious economic difficulties and social disorder persisted because the Communists cut the main routes of transportation of food, indispensables, and armaments. Insurgency occurred in every region of the nation, spurred by Communist forces, and hundreds of battalions moved against the capital city of Phnom Penh (Kiernan 2002, 32).

Cambodia’s insurgent forces were split between the hard-line Khmer Rouge and moderate, pro-Vietnamese Hanoi Khmer. The Hanoi Khmer controlled the Khmer Communist movement in Prey Veng in the Eastern Zone. Across the Mekong River was the Khmer Rouge’s occupied zone. The Khmer Rouge was preoccupied with military questions. Operations took the form of three successive storming attacks in 1973, 1974, and 1975, aimed at capturing Phnom Penh. The first storming operation was carried out on between May and July 1973; rebel troops were spurred forward by the vision of liberating Phnom Penh. “In early 1974, the rebel forces regrouped and formed a loop around Phnom Penh as they readied themselves for their second attack. Although they were not able to capture the capital, by the end of the year they had prevented travel by road between Phnom Penh and the port city of Kompong Som. Supplies for the capital had to be supplied by air or via the Mekong River. The final attack was planned for the 1975 dry season. By the end of 1974, all roads to the capital were cut, and in the early hours of January 1, rebel forces opened their bombardment (Becker 1998, 158-159; Chandler 1992, 104-109). The troops stationed along the Mekong River were able to cut lines of supply for food, fuel, and ammunition, to starve The Killing Field, 1975-1979 The “Killing Field” was a huge massacre committed by Pol Pot’s Khmer Rouge between 1975 and 1979. The Khmer Rouge, who took over its power from Lon Nol, established a very nationalistic regime called Democratic Kampuchea that maintained a pro-China and procommunist stance. Its regime purged Chia Sim and Heng Samrin, who were allied with Vietnam, through what is now infamously known as the Angka, a secret police. With the help of the Angka, Khmer Rouge maintained a very strong public mobilization system. From 1975 to December 1978, when Vietnam began its invasion, the Khmer Rouge committed massive public executions of more than 2,000,000 people including what it classified as pro-Americans, procapital and proimperialists under the slogan of “Let’s Complete a Perfect Socialist Revolution by extorting the revisionists.” the city gradually. The troops also fired the city, incurring many civilian casualties. Many of the republican soldiers ran out of ammunition and were eventually overrun by the Khmer Rouge. At last, on April 1, 1975, President Lon Nol resigned and flew out of the country. A last-minute peace talk initiated by the United States and involving Sihanouk failed, and the Khmer Rough captured Phnom Penh on April 17, 1975.

After the surrender of Phnom Penh, the Khmer Rouge established the Democratic Kampuchea government and expressed very strong nationalism. Between April and August 1975, GRUNK nominated Prince Sihanouk and Phen Nouth as prime minister and governor, respectively; however, Kieu Samphan, Ieng Sary, and Pol Pot of the Khmer Rouge held the real power. In particular, they established a strong public mobilization system with the help of Angka, the infamous confidential information organization, and adopted a pro-Chinese line when Pol Pot took hold of the real power, one year after expelling pro-Vietnamese Hanoi Khmer powers such as Chia Sim and Heng Samrin. The term Khmer Rouge originally included anti-Vietnamese Maoist communists, Khmer Vietmin, and pro-Vietnamese Hanoi Khmer, but now it generally refers to the Khmer Vietmin. For the Khmer Rouge, the two major enemies were the imperialist United States and Vietnam; accordingly, it made a clean sweep of people who were known to have sympathized with capitalist, imperialist, and pro-Vietnam or pro-China powers (Kiernan 2002, 3). In massacres carried out by the Khmer Rouge, well-known as the “Killing Field,” at least 2,000,000 people were executed between April 1975 and January 1977. This later came to the attention of the international community and received heavy criticism.

No official record remains of the number of people victimized during the 1970-1975 civil war and the subsequent Khmer Rouge-controlled Democratic Kampuchea (1975-1979). Most records and documents having to do with refugees and victims were destroyed when the Khmer Rouge took power, and the Democratic Kampuchea government established an unfriendly and exclusive political system. In spite of this, solid arguments exist for the assessment that approximately 741,000 Cambodians died at the hands of Pol Pot’s regime (Ayres 2000, 97). More than 200,000 Khmer people were massacred between 1975 and 1979, in addition to those who died during the civil war itself, and the number of wounded is estimated in the thousands (Becker 1998, 1; Chandler 1996, 212; Osborne 1994, 9; Vickery 1984).

The Insurgents: The People’s Republic of Kampuchea and Continual Civil War (1979-1991)

The successful Communist revolution undertaken by the Khmer Rouge in 1975 and the establishment of the Democratic Kampuchea did not mean the end of the civil war. In fact, the reign of the Khmer Rouge and its consequent state building caused the spread of the new conflict and civil war. After the establishment of the Democratic Kampuchea in 1975, tension grew within the Khmer Rouge. The confrontation between the Khmer Vietmin, with Pol Pot, Kieu Samphan, and Ieng Sary at its center, and the Hanoi Khmer, with Chia Sim, Heng Samrin, and Hun Sen at the center, was especially linked to the establishment of relations with China, Vietnam, and the Soviet Union. Pol Pot, who came to possess the real political power following expulsion of the pro-Vietnamese powers in the power struggle of 1976, strongly adopted a pro-Chinese line in foreign policy, while domestically he carried out state building according to the model of China’s “Great Leap Forward” and “Cultural Revolution,” conducting a grand purge (Chandler 1992, 70; Martin 1994, 210). Moreover, based on old national sentiments, the Pol Pot administration dispatched troops to the Mekong Delta region, where territorial disputes with Vietnam had persisted for a long time; in April 1977 they attacked the Cambodia-Vietnam border area, where the Vietnamese refugees were settled, and killed a great many Vietnamese.


The Mekong Delta area bordering Cambodia and Vietnam was the region of confrontation during border disputes stemming from the agreement of the Brevié Line during the French colonial period in 1939. Around 1 million Cambodians lived in Vietnamese territory, and around 500,000 Vietnamese were residing in Cambodian territory at the time of the incident.

The strained relations surrounding the border of the two countries finally developed into a war; Vietnamese troops attacked Cambodia on April 6, 1977. The fighting, which continued for weeks, caused approximately 8,000 deaths on both sides, and the Pol Pot administration broke off diplomatic relations with Vietnam in December of the same year. Cambodia and Vietnam both repeatedly attacked and retreated between January and April of 1978, and in May 1978, Vietnam supported the Kompong Cham people’s uprising led by the National United Front for National Salvation (KNUFNS), headed by Heng Samrin in pro-Vietnamese Hanoi Khmer. Ultimately, Vietnam decisively attacked Cambodia in December 1978, with Heng Samrin’s KNUFNS in the vanguard, followed by five Vietnamese regular army divisions. Having relatively great military strength, Vietnam expelled Pol Pot’s Khmer Rouge in only seventeen days and established the People’s Republic of Kampuchea in January 1979, with Heng Samrin, the pro-Vietnam figure, as its head (Gottesman 2002, 10-11).

Establishment of the PRK, which was supported by Vietnamese military economic aid, gave the Cambodian civil war a new aspect. In October 1979, the Khmer Rouge army, which had lost three-fourths of its total strength, arrived at the Khmer-Thai border (Martin 1994, 240-241). A significant number of Khmer Rouge troops had been able to escape the Vietnamese forces and reposition themselves in the border regions. Pol Pot’s remaining army controlled only unpopulated jungle along the 400-mile Thai border, usually mountainous areas difficult for attackers to approach. They survived there only because of Thailand’s readiness to supply them and to allow the leaders of the widely separated Khmer Rouge camps easy contact with one another via Thai roads. China supplied them with food and arms, delivered to the Cambodians by the Thai military (Kamm 1998, 150).


Former Khmer Rouge leaders had close ties to Sihanouk’s National Army (ANS: Armée Nationale Sihanoukienne), which conducted rebel operations near the Thai border; additionally, the Khmer People’s National Liberation Armed Forces (KPNLAF), controlled by the former prime minister of the Khmer Republic administration, Son Sann, conducted anticommunist resistance across the border. These groups proposed to ally themselves against the PRK government in Phnom Penh (Martin 1994, 248-250). In 1981, Sihanouk formed his own organization, National United Front for an Independent, Neutral, Peaceful, and Cooperative Cambodia (FUNCINPEC: Front Uni National pour un Cambodge indépendant, neutre, pacifique, et coopératif), and its military unit, the ANS (Sihznouk’s National Army).

In June 1982, Khieu Samphan of the Khmer Rouge, Son Sann of the KPNLF (Khmer People’s National Liberation Front), and Sihanouk of FUNCINPEC attended a three-party conference in Kuala Lumpur, Malaysia, with China as mediator, and finally announced the formation of Coalition Government of Democratic Kampuchea (CGDK) (Gottesman 2002, 139). They demanded withdrawal of the Vietnamese military from Cambodia and suspension of domestic interference, and declared their intent to continue to resist the PRK government in Phnom Penh. Western countries, including the United States and most ASEAN countries, promised political and humanitarian support for the CGDK, and China promised military support. In fact, on February 17, 1979, China attacked northern Vietnam with 320,000 troops to punish Vietnam for its attack on Cambodia, inflicting thousands of casualties within a two-week period (Chandler 1996, 229). The United Nations also recognized the CGDK and promised humanitarian support to end the Cambodian civil war.

Meanwhile, Vietnamese military operations to suppress the rebellion against the PRK government continued. Vietnamese forces conducted offensive operations during the dry seasons, and the resistance forces counterattacked during the rainy seasons. “Toward the end of each year, as the rains stopped and the muddy roads dried out, the Vietnamese army went on the offensive. Capable of moving its artillery from place to place, the Vietnamese could pursue the Cambodian resistances and destroy its bases. Then, each spring, as the rains resumed, the resistance would strike back, destroying railroads, bridges, and fuel facilities and forcing the now immobilized Vietnamese to defend their hard-earned territory” (Gottesman 2002, 223). In 1982, Vietnam launched an attack on the Khmer Rouge base at Phom Melai in the Caramom Mountains. The following year, Vietnam bombarded civilian camps near the Thai border. The camps belonged to all three resistance groups. Hundreds of civilian casualties resulted, and more than 80,000 refugees fled to Thailand. However, damage to the resistance was not serious. In the 1984-1985 dry season, the Vietnamese again attacked the camps of all three resistance groups. This time, despite strong resistance, Vietnamese forces were able to sweep out the resistance camps in Cambodia and drive them into Thailand. The Vietnamese consolidated their gains by sealing the guerrilla route into the country, constructing trenches, erecting wire fences, and laying mines along the entire Thai-Cambodia border, using Cambodian forced labor (Kamm 1998, 201).

Causes of the War

The primary causes of the second civil war, fought by the PRK government and the CGDK between 1979 and 1991, evolved out of the 1970-1975 war and the establishment of the Democratic Kampuchea by the Khmer Rouge. The ongoing Cold War and the security concerns of countries with interests in Southeast Asia increased ideological conflicts and political confrontations within Cambodia and, as a result, propagated a new civil war. But unlike the first civil war, which was essentially a Communist revolution, the 1979-1991 civil war was characterized by even power struggles. Following the successful Communist revolution of the Khmer Rouge in the 1970-1975 civil war, regional security problems and a power struggle within the Khmer Rouge eventually provoked the interference of Vietnam, the outside power. The result was the emergence of various domestic conflicts caused by a combination of civil war and the competing security interests of the surrounding Southeast Asian countries, the United States, China, the Soviet Union, and others.

The 1979-1991 Cambodian civil war involved the strategic interests of the United States and the Soviet Union, as it did the historical and geographical interests of the surrounding countries—Vietnam, China, and Thailand. Vietnam, which had strained its relations on the Indochina peninsula by attacking Cambodia, primarily attempted to protect its national security by establishing governments in Cambodia and Laos that would accommodate Vietnam’s policies, thereby buffering potential threats posed by surrounding ASEAN countries, which were receiving support from the anticommunist United States, at the same time that it sought to exclude the influence of China, which acted as suzerain to the countries of Indochina. This situation also impacted the interests of the Soviet Union, which, as a rival of China, tried to buffer China’s status and influence in the Communist bloc by providing strong support for Indochina. Meanwhile, although the United States (which was still suffering from the nightmare of the Vietnam war) did not become directly involved in the Cambodian conflicts, they expedited support for the ASEAN countries and the rebel groups inside Cambodia to prevent the communization of the Indochina countries one after another (Chanda 1988; Miller 1990; Simon 1978).

The beginning of the second civil war was Vietnam’s attack on Cambodia. When Phnom Penh surrendered following the Vietnamese army’s attack on Cambodia in 1979, Heng Samrin’s KNUFNS established the People’s Republic of Kampuchea. Vietnam’s 200,000 troops controlled major population centers as well as the countryside from 1979 to 1989. In contrast, Heng Samrin’s 30,000 soldiers were plagued by low morale and desertion. Although guerrilla resistance continued, there is evidence that Heng Samrin’s PRK supported the guerrillas in terms of logistic and moral aspects. Vietnam’s support of the Heng Samrin regime, which was dependent on Vietnam in every respect, was not enough. Especially, in rural areas, security was not total, and transportation routes were hampered by guerrilla activity. The Cambodian people were alienated from Vietnam because of the latter’s presence in Cambodia. The settlement of Vietnamese in Cambodia further estranged the Cambodian people. Against this background, by the end of the decade Cambodian nationalism was again emerging against the traditional enemy, the Vietnamese.


As the time passed, the Cambodian civil war appeared to be dominated by the PRK government troops and the Vietnamese troops; economic sanctions by the United States, pressure from the UN to solve the refugee problems in a humanitarian way and end the conflict, and peace conferences organized by the ASEAN countries were all putting pressure on the Phnom Penh government and Vietnam. Vietnam stationed troops in Cambodia, even after the surrender of Phnom Penh and the establishment of the PRK, to shatter the resistance of the CGDK, including the Khmer Rouge. Vietnam stationed 100,000 troops out of 200,000 in southern Cambodia and committed the rest to sweeping actions against the Khmer Rouge, gradually seizing the local towns. In fact, a substantial reason for stationing Vietnamese troops in Cambodia was that Vietnam feared China’s revenge and the conflicts along the Thai border. The Khmer Rouge, many of whom escaped over the Chinese border, along with Sihanouk’s FUNCINPEC and Son Sann’s KPNLF, continued to carry out resistance activities with the support of China and Thailand.

Conflict Status

The rapid increase in the number of refugees escaping from Cambodia across the Thai border served to concentrate the international community’s attention on the Cambodian civil war. Refugees who tried to cross into Thailand were often threatened with of blackmail and violence from the nascent village militias, bandits, and the Khmer Rouge (Gottesman 2002, 41). At least 600,000 Cambodians moved their homes during the Pol Pot era and as the Vietnamese invasion approached the Thai border. The international community, through various official and nongovernmental relief organizations, provided the Khmer Rouge and the Cambodian refugees with food and medical care (Kamm 1998, 151). The international community conducted a massive relief action, coordinated by the United States through the United Nations International Children’s Emergency Fund (UNICEF) and the World Food Program. In the decade following 1972, about $400 million was provided. The United States contributed nearly $100 million out of the $400 million. At its peak, more than 500,000 Cambodians were stationed in the refugee camps along the Thai-Cambodian border.

Duration Tactics

Consequently, the second Cambodian civil war, which started with Vietnam’s attack on Cambodia in 1979, unlike the 1970-1975 war, was accompanied by international attention and active relief activities. In July 1979, the UN convoked the Geneva International Conference to discuss the Cambodian crisis, urging the Heng Samrin administration and Vietnam to conclude the Cambodian conflict as soon as possible. The ASEAN also had a deep interest in Indochinese conflicts, including the Cambodian crisis, which had the potential to develop into a crisis comprising all the ASEAN countries. The ASEAN therefore expressed serious concern, requesting a prompt withdrawal of all foreign troops from Cambodia and strongly opposing the hegemony building of China, the Soviet Union, and Vietnam in Indochina (Kamm 1998, 193). This demonstrated that the Cambodian civil war was not merely a Cambodian domestic problem or a bilateral conflict between Cambodia and Vietnam but an international issue with regional security implications.

External Military Intervention

In 1986, Vietnam withdrew their occupation forces from Cambodian territory. Succumbing to international pressure, Vietnam withdrew its remaining forces in 1989-1990. This development allowed the PRK to begin making economic and constitutional reforms to ensure its political future. In April 1989, Vietnam and Cambodia announced that the final withdrawal would be completed by September 1989. Changes in the domestic and international environment were the major reason for Vietnam’s withdrawal from Cambodia. To overcome its domestic economic crisis, which had peaked by the mid-1980s, Vietnam gradually sought methods of economic revolution such as “Doi Moi,” while considering the withdrawal of its troops in Cambodia to reduce the enormous military expenditure. Especially after the Soviet Union’s adoption of perestroika in 1985 based on the “New Thinking,” the United States reduced its military aid to Vietnam, and therefore Vietnam no longer had the economic capability to maintain troops in Cambodia.

In the middle of this, gradual changes began to appear inside the PRK government in the mid- 1980s. When there was a lull in the civil war with the dominance of the PRK and the Vietnamese troops, the new generation of political leaders, bolstered by nationalism and unilateralism, began to take most of the major positions in the Kampuchean (or Khmer) People’s Revolution Party (KPRP) instead of the first-generation leaders who were trained in Hanoi. The newly authorized prime minister, Hun Sen, declared, “What we are afraid of is not the liberalist economy, but famine of the people,” and pursued changes in economic policies and improvement in international relations. The Khmer People’s Revolution Party, the ruling party of Cambodia, abandoned its socialistic line in April 1989 and began to carry out a revolutionary policy of accommodating a multiparty system and a market economy, and changed the title of the party to the Cambodian People’s Party (Ayres 2000, 145). In addition, the Hun Sen government also complied with the terms of the peace agreement with the CGDK rebels due to pressures from the international community to peacefully solve the Cambodian issue.

Conflict Management Efforts

The end of the Cambodian civil war was the final result of the endeavors of the international community to solve the Cambodian crisis and change the environment of the international system. Unlike the 1970-1975 war, the second Cambodian civil war, which was caused primarily by the Vietnam’s attack on Cambodia in 1979, was regarded as the main threat to the security of Indochina. Accordingly, the international community ultimately persuaded the warring parties to conclude a peace agreement through various arbitration aimed at facilitating humanitarian aid and a peaceful resolution of the Cambodian crises. The international focus on reconciliation in the post-Cold War environment, exemplified by the Soviet Union’s policy of perestroika in particular, is thought to have heavily influenced the Cambodian civil war. The post-Cold War period, a time of transition in international security, promoted an environment of reconciliation and cooperation among Southeast Asian countries, helping them to end the Cambodian crisis and solve the Indochina problem.

In 1989, the UN passed its motion of intervention in the Cambodian crisis with 124 approvals, 17 objections, and 12 abstentions. For a month after July 1989, representatives of eighteen countries, including four Cambodian political parties, met in Paris to negotiate a settlement. They attempted to agree on main objectives that were regarded as crucial for the future of Cambodia: a completed and verified withdrawal of Vietnamese troops, the prevention of the restoration of the Khmer Rouge, and self-determination for the Cambodian people. The Paris conference also made some progress in the following areas: an international control mechanism, the interpretation of international guarantees for Cambodia’s independence and neutrality, plans for the repatriation of refugees and displaced persons, the reconstruction of the Cambodian economy, and cease-fire procedures. However, they had to wait a year or so until a comprehensive settlement was agreed upon. A year later—that is, on October 23, 1991—the concerned parties convened again in Paris to sign the settlement giving the UN full authority to supervise a cease-fire, to repatriate the displaced Khmer along the border with Thailand, to disarm and demobilize the factional armies, and to prepare the country for free and fair elections.


The international security environment after World War II, the so-called Cold War, heavily influenced the communization of countries of the Indochina peninsula, such as Cambodia and Laos, as did the Vietnam War. In Cambodia’s case, the country experienced prolonged civil war in a series of “political vortices” evoked after its independence in 1953, and the Cambodian people suffered deaths and famine during this period. A combination of the Cold War structure in international politics, the ideological conflicts of the countries surrounding Cambodia, and Cambodia’s own political conflicts and domestic divisions resulted in a condition of extended civil war. Because of its location in the middle of Southeast Asia, and because of the persistent intervention and influence of the surrounding powers, Cambodia’s civil war conflicts and confrontation structure were a function of the dynamic relations between various opposing domestic political powers and those outside the country.

After the signing of the Paris Peace Agreement in 1991, UNTAC (United Nations Transitional Authority in Cambodia) was established in Cambodia. A general election was held under the supervision of the UN in May 1993, the result of which was that Cambodia again became the Kingdom of Cambodia, a constitutional monarchy. However, this political process has not resulted in a completely peaceful settlement for Cambodia since 1993. In 1997, a coup d’état

was attempted by Hun Sen that threatened the general election that was to be held in 1998; intermittent violence occurs, along with suppression of parties that oppose Prime Minister Hun Sen and the Cambodian People’s Party (CPP) government. Although various attempts and arbitration by the UN and the ASEAN to peacefully resolve the Cambodian civil war were successful in settling physical clashes and military conflicts between the political parties in Cambodia, there is no guarantee of Cambodia’s complete democratization and political stability.

It is the responsibility of various political powers and the Cambodian people to ensure peace and stability in Cambodia. The Cambodian people have already experienced tragic suffering in the vortex of the long civil war, and they desperately want peace and political stability. The challenge now is to completely dissolve potential political conflicts that still exist inside Cambodia and to achieve peaceful prosperity and stability. To reach these goals, a clear understanding of the causes and conditions of the past civil wars is necessary, as are the continuous observation and support of the international community.