Khmer Rouge rule of Cambodia

By the time of the Khmer Rouge victory on April 17, 1975, Pol Pot and his associates occupied the most important positions in the Communist Party of Kampuchea (CPK) and in the state hierarchies. Pol Pot had been CPK general secretary since February 1963. His associates functioned as the party's Political Bureau, and they held a majority of the seats on the Central Committee.

Through the 1970s, and especially after mid-1975, the party was shaken by factional struggles, including armed attempts to topple Pol Pot. Punitive measures resulted in 1977 and 1978 when hundreds of thousands of people, including some of the most important CPK leaders, were executed.

The Khmer Rouge abolished the Royal Government of National Union of Kampuchea (established in 1970). Cambodia did not have any sort of government until the proclamation of the Constitution of Democratic Kampuchea on January 5, 1976.

The Khmer Rouge continued to use King Norodom Sihanouk as a figurehead for the government until April 2, 1976, when Sihanouk resigned as head of state. Sihanouk remained under insecure house arrest in Phnom Penh, until late in the war with Vietnam when he departed for the United States where he made Democratic Kampuchea's case before the Security Council. He eventually relocated to China.

The "rights and duties of the individual" were briefly defined in Article 12. They included none of what are commonly regarded as guarantees of political human rights except the statement that "men and women are equal in every respect." The document declared, however, that "all workers" and "all peasants" were "masters" of their factories and fields. An assertion that "there is absolutely no unemployment in Democratic Kampuchea" rings true in light of the regime's massive use of force.

The Constitution defined Democratic Kampuchea's foreign policy principles in Article 21, the document's longest, in terms of "independence, peace, neutrality, and nonalignment." It pledged the country's support to anti-imperialist struggles in the Third World. In light of the regime's aggressive attacks against Vietnamese, Thai, and Lao territory during 1977 and 1978, the promise to "maintain close and friendly relations with all countries sharing a common border" bore little resemblance to reality.

Governmental institutions were outlined very briefly in the Constitution. The legislature, the Kampuchean People's Representative Assembly (KPRA), contained 250 members "representing workers, peasants, and other working people and the Kampuchean Revolutionary army." One hundred and fifty KPRA seats were allocated for peasant representatives; fifty, for the armed forces; and fifty, for worker and other representatives. The legislature was to be popularly elected for a five-year term. Its first and only election was held on March 20, 1976. "New people" apparently were not allowed to participate.

The executive branch of government also was chosen by the KPRA. It consisted of a state presidium "responsible for representing the state of Democratic Kampuchea inside and outside the country." It served for a five-year term, and its president was head of state. Khieu Samphan was the only person to serve in this office, which he assumed after Sihanouk's resignation. The judicial system was composed of "people's courts", the judges for which were appointed by the KPRA, as was the executive branch.

The Constitution did not mention regional or local government institutions. After assuming power, the Khmer Rouge abolished the old provinces (khet) and replaced them with seven zones; the Northern Zone, Northeastern Zone, Northwestern Zone, Central Zone, Eastern Zone, Western Zone, and Southwestern Zone. There were also two other regional-level units: the Kracheh Special Region Number 505 and, until 1977, the Siemreab Special Region Number 106.

The zones were divided into damban (regions) that were given numbers. Number One, appropriately, encompassed the Samlot region of the Northwestern Zone (including Battambang Province), where the insurrection against Sihanouk had erupted in early 1967. With this exception, the damban appear to have been numbered arbitrarily.

The damban were divided into srok (districts), khum (subdistricts), and phum (villages), the latter usually containing several hundred people. This pattern was roughly similar to that which existed under Sihanouk and the Khmer Republic, but inhabitants of the villages were organized into krom (groups) composed of ten to fifteen families. On each level, administration was directed by a three-person committee (kanak, or kena).

CPK members occupied committee posts at the higher levels. Subdistrict and village committees were often staffed by local poor peasants, and, very rarely, by "new people." Cooperatives (sahakor), similar in jurisdictional area to the khum, assumed local government responsibilities in some areas.

According to Pol Pot, Cambodia was made up of four classes: peasants and workers, bourgeoisie, capitalists, and feudalists. Post-revolutionary society, as defined by the 1976 Constitution of Democratic Kampuchea, consisted of workers, peasants, and "all other Kampuchean working people." No allowance was made for a transitional stage such as China's "New Democracy" in which "patriotic" landlord or bourgeois elements were permitted to play a role in socialist construction.

Sihanouk writes that in 1975 he, Khieu Samphan, and Khieu Thirith went to visit Zhou Enlai, who was gravely ill. Zhou warned them not to attempt to achieve communism in a single step, as China had attempted in the late 1950s with the Great Leap Forward. Khieu Samphan and Khieu Thirith "just smiled an incredulous and superior smile."[2] Khieu Samphan and Son Sen later boasted to Sihanouk that "we will be the first nation to create a completely communist society without wasting time on intermediate steps."[2]

Although conditions varied from region to region, a situation that was, in part, a reflection of factional divisions that still existed within the CPK during the 1970s, the testimony of refugees reveals that the most salient social division was between the politically suspect "new people", those driven out of the towns after the communist victory, and the more reliable "old people", the poor and lower middle-class peasants who had remained in the countryside. Despite the ideological commitment to radical equality, CPK members and the armed forces constituted a clearly recognizable elite.

The working class was a negligible factor because of the evacuation of the urban areas and the idling of most of the country's few factories. The one important working class group in pre-revolutionary Cambodia—labourers on large rubber plantations—traditionally had consisted mostly of Vietnamese emigrants and thus was politically suspect.

The number of people, including refugees, living in the urban areas on the eve of the communist victory probably was somewhat more than 3 million, out of the total population of roughly 8 million. As mentioned, despite their rural origins, the refugees were considered "new people"—that is, people unsympathetic to Democratic Kampuchea. Some doubtless passed as "old people" after returning to their native villages, but the Khmer Rouge seem to have been extremely vigilant in recording and keeping track of the movements of families and of individuals.

The lowest unit of social control, the krom (group), consisted of ten to fifteen nuclear families whose activities were closely supervised by a three-person committee. The committee chairman was selected by the CPK. This grass roots leadership was required to note the social origin of each family under its jurisdiction and to report it to persons higher up in the Angkar hierarchy. The number of "new people" may initially have been as high as 2.5 million.

The "new people" were treated as forced labourers. They were constantly moved, were forced to do the hardest physical labour, and worked in the most inhospitable, fever-ridden parts of the country, such as forests, upland areas, and swamps. "New people" were segregated from "old people", enjoyed little or no privacy, and received the smallest rice rations. When the country experienced food shortages in 1977, the "new people" suffered the most.

The medical care available to them was primitive or nonexistent. Families often were separated because people were divided into work brigades according to age and sex and sent to different parts of the country. "New people" were subjected to unending political indoctrination and could be executed without trial.

The situation of the "old people" under Khmer Rouge rule was more ambiguous. Refugee interviews reveal cases in which villagers were treated as harshly as the "new people", enduring forced labour, indoctrination, the separation of children from parents, and executions; however, they were generally allowed to remain in their native villages.

Because of their age-old resentment of the urban and rural elites, many of the poorest peasants probably were sympathetic to Khmer Rouge goals. In the early 1980s, visiting Western journalists found that the issue of peasant support for the Khmer Rouge was an extremely sensitive subject that officials of the People's Republic of Kampuchea were not inclined to discuss.

Although the Southwestern Zone was one original centre of power of the Khmer Rouge, and cadres administered it with strict discipline, random executions were relatively rare, and "new people" were not persecuted if they had a cooperative attitude. In the Western Zone and in the Northwestern Zone, conditions were harsh. Starvation was general in the latter zone because cadres sent rice to Phnom Penh rather than distributing it to the local population. In the Northern Zone and in the Central Zone, there seem to have been more executions than there were victims of starvation. Little reliable information emerged on conditions in the Northeastern Zone, one of the most isolated parts of Cambodia.

On the surface, society in Democratic Kampuchea was strictly egalitarian. The Khmer language, like many in Southeast Asia, has a complex system of usages to define speakers' rank and social status. These usages were abandoned. People were encouraged to call each other "friend", or "comrade" (in Khmer, មិត្ដ mitt), and to avoid traditional signs of deference such as bowing or folding the hands in salutation.

Language was transformed in other ways. The Khmer Rouge invented new terms. People were told they must "forge" (lot dam) a new revolutionary character, that they were the "instruments" (opokar) of the Angkar, and that nostalgia for pre-revolutionary times (chheu satek arom, or "memory sickness") could result in their receiving Angkar's "invitation" to be deindustrialised and to live in a concentration camp.

Members and candidate members of the CPK, local-level leaders of poor peasant background who collaborated with the Angkar, and members of the armed forces had a higher standard of living than the rest of the population. Refugees agree that, even during times of severe food shortage, members of the grass-roots elite had adequate, if not luxurious, supplies of food. One refugee wrote that "pretty new bamboo houses" were built for Khmer Rouge cadres along the river in Phnom Penh.

According to Craig Etcheson, an authority on Democratic Kampuchea, members of the revolutionary army lived in self-contained colonies, and they had a "distinctive warrior-caste ethos." Armed forces units personally loyal to Pol Pot, known as the "Unconditional Divisions", were a privileged group within the military.

Although their revolutionary ideology was extreme, the highest ranks of the Khmer Rouge leadership had a tendency to nepotism similar of the Sihanouk-era elite. Pol Pot's wife, Khieu Ponnary, was head of the Association of Democratic Khmer Women and her younger sister, Khieu Thirith, served as minister of social action. These two women were considered among the half-dozen most powerful personalities in Democratic Kampuchea. Son Sen's wife, Yun Yat, served as minister for culture, education and learning.

Several of Pol Pot's nephews and nieces were given jobs in the Ministry of Foreign Affairs. One of Ieng Sary's daughters was appointed head of the Calmette Hospital although she had not graduated from secondary school. A niece of Ieng Sary was given a job as English translator for Radio Phnom Penh although her fluency in the language was relative.

Family ties were important, both because of the culture and because of the leadership's intense secretiveness and distrust of outsiders, especially of pro-Vietnamese communists. Different ministries, such as the Ministry of Foreign Affairs and the Ministry of Industry, were controlled and exploited by powerful Khmer Rouge families. Administering the diplomatic corps was regarded as an especially profitable fiefdom.

Democratic Kampuchea's economic policy was similar to, and possibly inspired by, China's radical Great Leap Forward that carried out immediate collectivisation of the Chinese countryside in 1958. During the early 1970s, the Khmer Rouge established "mutual assistance groups" in the areas they occupied.

James Tyner (2017) argues that the Cambodian economy under the Khmer Rouge was state capitalist.[3]

After 1973, these were organised into "low-level cooperatives" in which land and agricultural implements were lent by peasants to the community but remained their private property. "High-level cooperatives", in which private property was abolished and the harvest became the collective property of the peasants, appeared in 1974. "Communities", introduced in early 1976, were a more advanced form of high-level cooperative in which communal dining was instituted. State-owned farms also were established.

Far more than the Chinese Maoist communists, the Khmer Rouge pursued the ideal of economic self-sufficiency, specifically the version that Khieu Samphan had outlined in his 1959 doctoral dissertation. Currency was abolished, and domestic trade or commerce could be conducted only through barter. Rice, measured in tins, became the most important medium of exchange, although people also bartered gold, jewelry, and other personal possessions.

Foreign trade was almost completely halted, though there was a limited revival in late 1976 and early 1977. China was the most important trading partner, but commerce amounting to a few million dollars was also conducted with France, the United Kingdom, and with the United States through a Hong Kong intermediary.

From the Khmer Rouge perspective, the country was free of foreign economic domination for the first time in its 2,000-year history. By mobilising the people into work brigades organised in a military fashion, the Khmer Rouge hoped to unleash the masses' productive forces.

There was an "Angkorian" component to economic policy. That ancient kingdom had grown rich and powerful because it controlled extensive irrigation systems that produced surpluses of rice. Agriculture in modern Cambodia depended, for the most part, on seasonal rains.

By building a nationwide system of irrigation canals, dams, and reservoirs, the leadership believed it would be possible to produce rice on a year-round basis. It was the "new people" who suffered and sacrificed the most to complete these ambitious projects.

Although the Khmer Rouge implemented an "agriculture first" policy in order to achieve self-sufficiency, they were not, as some observers have argued, "back-to-nature" primitivists. Although the 1970–75 war and the evacuation of the cities had destroyed or idled most industry, small contingents of workers were allowed to return to the urban areas to reopen some plants.

Like their Chinese counterparts, the Cambodian communists had great faith in the inventive power and the technical aptitude of the masses, and they constantly published reports of peasants' adapting old mechanical parts to new uses. Similarly to Mao's regime, which had attempted unsuccessfully to build a new steel industry based on backyard furnaces during the Great Leap Forward, the Khmer Rouge sought to move industry to the countryside. Significantly, the seal of Democratic Kampuchea displayed not only sheaves of rice and irrigation sluices, but also a factory with smokestacks.

The Khmer Rouge regarded traditional education with undiluted hostility. After the fall of Phnom Penh, they executed thousands of teachers. Those who had been educators prior to 1975 survived by hiding their identities.

Aside from teaching basic mathematical skills and literacy, the major goal of the new educational system was to instill revolutionary values in the young. For a regime at war with most of Cambodia's traditional values, this meant that it was necessary to create a gap between the values of the young and the values of the nonrevolutionary old.

The regime recruited children to spy on adults. The pliancy of the younger generation made them, in the Angkar's words, the "dictatorial instrument of the party." In 1962 the communists had created a special secret organisation, the Democratic Youth League, that, in the early 1970s, changed its name to the Communist Youth League of Kampuchea. Pol Pot considered Youth League alumni as his most loyal and reliable supporters, and used them to gain control of the central and of the regional CPK apparatus. The powerful Khieu Thirith, minister of social action, was responsible for directing the youth movement.

Hardened young cadres, many little more than twelve years of age, were enthusiastic accomplices in some of the regime's worst atrocities. Sihanouk, who was kept under virtual house arrest in Phnom Penh between 1976 and 1978, wrote in War and Hope that his youthful guards, having been separated from their families and given a thorough indoctrination, were encouraged to play cruel games involving the torture of animals. Having lost parents, siblings, and friends in the war and lacking the Buddhist values of their elders, the Khmer Rouge youth also lacked the inhibitions that would have dampened their zeal for revolutionary terror.

Health facilities in the years 1975 to 1978 were abysmally poor. Many physicians either were executed or were prohibited from practicing. It appears that the party and the armed forces elite had access to Western medicine and to a system of hospitals that offered reasonable treatment, but ordinary people, especially "new people", were expected to use traditional plant and herbal remedies that were of debatable usefulness. Some bartered their rice rations and personal possessions to obtain aspirin and other simple drugs.

The deportations were one of the markers of the beginning of the Khmer Rouge rule. They demanded and then forced the people to leave the cities and live in the countryside.[4] Phnom Penh—populated by 2.5 million people[5] —was soon nearly empty. The roads out of the city were clogged with evacuees. Similar evacuations occurred throughout the nation.

The conditions of the evacuation and the treatment of the people involved depended often on which military units and commanders were conducting the specific operations. Pol Pot's brother – Chhay, who worked as a Republican journalist in the capital – was reported to have died during the evacuation of Phnom Penh.

Even Phnom Penh's hospitals were emptied of their patients. The Khmer Rouge provided transportation for some of the aged and the disabled, and they set up stockpiles of food outside the city for the refugees; however, the supplies were inadequate to sustain the hundreds of thousands of people on the road. Even seriously injured hospital patients, many without any means of conveyance, were summarily forced to leave regardless of their condition.

The foreign community, about 800 people, was quarantined in the French embassy compound, and by the end of the month the foreigners were taken by truck to the Thai border. Khmer women who were married to foreigners were allowed to accompany their husbands, but Khmer men were not permitted to leave with their foreign wives.

Western historians claim that the motives were political, based on deep-rooted resentment of the cities. The Khmer Rouge was determined to turn the country into a nation of peasants in which the corruption and "parasitism" of city life would be completely uprooted. In addition, Pol Pot wanted to break up the "enemy spy organisations" that allegedly were based in the urban areas. Finally, it seems that Pol Pot and his hard-line associates on the CPK Political Bureau used the forced evacuations to gain control of the city's population and to weaken the position of their factional rivals within the communist party.

Remains of victims of the Khmer Rouge in the Kampong Trach Cave, Kiry Seila Hills, Rung Tik (Water Cave) or Rung Khmao (Dead Cave).

A security apparatus called Santebal was part of the Khmer Rouge organizational structure well before April 17, 1975, when the Khmer Rouge took control over Cambodia. Son Sen, later the Deputy Prime Minister for Defense of Democratic Kampuchea, was in charge of the Santebal, and in that capacity he appointed Comrade Duch to run its security apparatus. When the Khmer Rouge took power in 1975, Duch moved his headquarters to Phnom Penh and reported directly to Son Sen. At that time, a small chapel in the capital was used to incarcerate the regime's prisoners, who totaled fewer than two hundred. In May 1976, Duch moved his headquarters to its final location, a former high school known as Tuol Sleng, which could hold up to 1,500 prisoners.

Skulls of Khmer Rouge victims

The Khmer Rouge government arrested, tortured and eventually executed anyone suspected of belonging to several categories of supposed "enemies":

• Anyone with connections to the former government or with foreign governments.
• Professionals and intellectuals—in practice this included almost everyone with an education, people who understood a foreign language and even people who required glasses.[6] However, Pol Pot himself was a university-educated man (albeit a drop-out) with a taste for French literature and was also a fluent French speaker. Many artists, including musicians, writers and film makers were executed. Some like Ros Serey Sothea, Pen Ran and Sinn Sisamouth gained posthumous fame for their talents and are still popular with Khmers today.
• Ethnic Vietnamese, ethnic Chinese, ethnic Thai and other minorities in Eastern Highland, Cambodian Christians (most of whom were Catholic, and the Catholic Church in general), Muslims and the Buddhist monks.
• "Economic saboteurs:" many of the former urban dwellers (who had not starved to death in the first place) were deemed to be guilty by virtue of their lack of agricultural ability.

Through the 1970s, and especially after mid-1975, the party was also shaken by factional struggles. There were even armed attempts to topple Pol Pot. The resultant purges reached a crest in 1977 and 1978 when thousands, including some important KCP leaders, were executed.

Today, examples of the torture methods used by the Khmer Rouge can be seen at the Tuol Sleng Genocide Museum. The museum occupies the former grounds of a high school turned prison camp that was operated by Khang Khek Ieu, more commonly known as "Comrade Duch".

The torture system at Tuol Sleng was designed to make prisoners confess to whatever crimes they were charged with by their captors. In their confessions, the prisoners were asked to describe their personal background. If they were party members, they had to say when they joined the revolution and describe their work assignments in DK. Then the prisoners would relate their supposed treasonous activities in chronological order. The third section of the confession text described prisoners' thwarted conspiracies and supposed treasonous conversations. At the end, the confessions would list a string of traitors who were the prisoners' friends, colleagues, or acquaintances. Some lists contained over a hundred names. People whose names were in the confession list were often called in for interrogation. Typical confessions ran into thousands of words in which the prisoner would interweave true events in their lives with imaginary accounts of their espionage activities for the CIA, the KGB, or Vietnam.

Some 17,000 people passed through Tuol Sleng Centre (also known as S-21) before they were taken to sites (also known as The Killing Fields), outside Phnom Penh such as Choeung Ek where most were executed (mainly by pickaxes to save bullets) and buried in mass graves. Of the thousands who entered Tuol Sleng only twelve are known to have survived.

Modern research has located 20,000 mass graves from the Khmer Rouge era throughout Cambodia. The analysis of mass graves revealed the remains of 1,386,734 victims of execution.[7] Detailed demographic study demonstrates that the total population loss in Cambodia was 1.671 and 1.871 million people from 1975 to 1979, or 21 to 24 percent of Cambodia's 1975 population.[1] An additional 300,000 Cambodians starved to death between 1979 and 1980, largely as a result of the after-effects of Khmer Rouge policy.[8]

Article 20 of the 1976 Constitution of Democratic Kampuchea guaranteed religious freedom, but it also declared that "all reactionary religions that are detrimental to Democratic Kampuchea and the Kampuchean People are strictly forbidden." About 85 percent of the population follows the Theravada school of Buddhism. The country's 40,000 to 60,000 Buddhist monks, regarded by the regime as social parasites, were defrocked and forced into labour brigades.

Many monks were executed; temples and pagodas were destroyed[9] or turned into storehouses or gaols. Images of the Buddha were defaced and dumped into rivers and lakes. People who were discovered praying or expressing religious sentiments were often killed. The Christian and Muslim communities also were even more persecuted, as they were labelled as part of a pro-Western cosmopolitan sphere, hindering Cambodian culture and society. The ruins of Angkor Wat escaped destruction as the Khmer Rouge considered it to be a symbol of the golden age of Cambodia which they were trying to recreate.

The Roman Catholic cathedral of Phnom Penh was completely razed.[9] The Khmer Rouge forced Muslims to eat pork, which they regard as forbidden (ḥarām). Many of those who refused were killed. Christian clergy and Muslim imams were executed. One hundred and thirty Cham mosques were destroyed.[9]

The Khmer Rouge banned by decree the existence of ethnic Chinese (Teochews), Vietnamese, Muslim Cham, and 20 other minorities, which altogether constituted 15% of the population at the beginning of the Khmer Rouge's rule.[10]

Tens of thousands of Vietnamese were raped, mutilated, and murdered in regime-organised massacres. Most of the survivors fled to Vietnam.

The Cham, a Muslim minority who are the descendants of migrants from the old state of Champa, were forced to adopt the Khmer language and customs. Their communities, which traditionally had existed apart from Khmer villages, were broken up. Forty thousand Cham were killed in two districts of Kampong Cham Province alone. Thai minorities living near the Thai border also were persecuted.

The state of the Chinese Cambodians was described as "the worst disaster ever to befall any ethnic Chinese community in Southeast Asia".[10] Cambodians of Chinese descent were massacred by the Khmer Rouge under the justification that they "used to exploit the Cambodian people".[11] The Chinese were stereotyped as traders and moneylenders, and therefore were associated with capitalism. Among the Khmer, the Chinese were also resented for their lighter skin color and cultural differences.[12] Hundreds of Chinese families were rounded up in 1978 and told that they were to be resettled, but were actually executed.[11] At the beginning of the Khmer Rouge's rule in 1975, there were 425,000 ethnic Chinese in Cambodia; by the end in 1979, there were 200,000. In addition to being a proscribed ethnic group by the government, the Chinese were predominantly city-dwellers, making them vulnerable to the Khmer Rouge's revolutionary ruralism.[10] The government of the People's Republic of China did not protest the killings of ethnic Chinese in Cambodia.[13] The policies of the Khmer Rouge towards Sino-Cambodians seems puzzling in light of the fact that the two most powerful people in the regime and presumably the originators of the racist doctrine, Pol Pot and Nuon Chea, both had mixed Chinese-Cambodian ancestry. Other senior figures in the Khmer Rouge state apparatus such as Son Sen and Ta Mok also had Chinese ethnic heritage.

In the late 1980s, little was known of Khmer Rouge policies toward the tribal peoples of the northeast, the Khmer Loeu. Pol Pot established an insurgent base in the tribal areas of Ratanakiri Province in the early 1960s, and he may have had a substantial Khmer Loeu following. Predominantly animist peoples, with few ties to the Buddhist culture of the lowland Khmers, the Khmer Loeu had resented Sihanouk's attempts to "civilise" them.

The 'Democratic Kampuchea' regime had closer ties with China (its main backer) and to a lesser extent with North Korea. In 1977, in a message congratulating the Cambodian comrades on the 17th anniversary of the CKP, Kim Jong-Il congratulated the Cambodian people for having "wiped out [...] counterrevolutionary group of spies who had committed subversive activities and sabotage"[14] Only China, North Korea, Egypt, Albania, Cuba, Laos, Vietnam (until December 1977), Romania and Yugoslavia had diplomatic missions in Phnom Penh.[15]

The Khmer Rouge frequently launched raids along the borders with Thailand and Vietnam. In 1975, Khmer Rouge troops raided Thổ Chu Island and carried out bloody massacres of islanders. On April 1978, they launched an attack in An Giang province and massacred 3,157 civilians of Ba Chúc town.

Not content with ruling Cambodia, the KR leaders also dreamed of reviving the Angkorian empire of a thousand years earlier, which ruled over large parts of what today are Thailand and Vietnam. This involved launching military attacks into southern Vietnam in which thousands of unarmed villagers were massacred.

Immediately following the Khmer Rouge victory in 1975, there were skirmishes between their troops and Vietnamese forces. A number of incidents occurred in May 1975. The Cambodians launched attacks on the Vietnamese islands of Phú Quốc and Thổ Chu causing the death of over 500 civilians[16] and intruded into Vietnamese border provinces. In late May, at about the same time that the United States launched an air strike against the oil refinery at Kompong Som, following the Mayagüez incident, Vietnamese forces seized the Cambodian island of Poulo Wai. According to Republic of Vietnam, Poulo Wai was a part of Vietnam since the 18th century and the island was under Cambodian administrative management in 1939 in accordance with decisions of French conlonists. Vietnam has recognized Poulo Wai as part of Cambodia since 1976, and the recognition is seen as a sign of goodwill by Vietnam to preserve its relationship with Cambodia.[17]

The following month, Pol Pot and Ieng Sary visited Hanoi. They proposed a friendship treaty between the two countries, an idea that met with a cool reception from Vietnam's leaders. Although the Vietnamese evacuated Poulo Wai in August, incidents continued along Cambodia's northeastern border. At the instigation of the Phnom Penh regime, thousands of Vietnamese also were driven out of Cambodia.

The Mayagüez

Relations between Cambodia and Vietnam improved in 1976, in part because of Pol Pot's preoccupation with intraparty challenges. In May Cambodian and Vietnamese representatives met in Phnom Penh in order to establish a commission to resolve border disagreements.

The Vietnamese, however, refused to recognize the Brévié Line—the colonial-era demarcation of maritime borders between the two countries—and the negotiations broke down. In late September, however, a few days before Pol Pot was forced to resign as prime minister, air links were established between Phnom Penh and Hanoi.

With Pol Pot back in the forefront of the regime in 1977, the situation rapidly deteriorated. Incidents escalated along all of Cambodia's borders. Khmer Rouge forces attacked villages in the border areas of Thailand near Aranyaprathet. Brutal murders of Thai villagers, including women and children, were the first widely reported concrete evidence of Khmer Rouge atrocities. There were also incidents along the Laos border.

At approximately the same time, villages in Vietnam's border areas underwent renewed attacks. In turn, Vietnam launched air strikes against Cambodia. From April 18 to 30, 1978, Cambodian troops, after invading Vietnamese province of An Giang, carried out the Ba Chúc massacre causing 3,157 civilian deaths. In September, border fighting resulted in as many as 1,000 Vietnamese civilian casualties. The following month, the Vietnamese counter-attacked in a campaign involving a force of 20,000 personnel.

Vietnamese defense minister General Võ Nguyên Giáp underestimated the tenacity of the Khmer Rouge, however, and was obliged to commit an additional 58,000 reinforcements in December. On January 6, 1978, Giap's forces began an orderly withdrawal from Cambodian territory. The Vietnamese apparently believed they had "taught a lesson" to the Cambodians, but Pol Pot proclaimed this a "victory" even greater than that of April 17, 1975. For several years, the Vietnamese government sought in vain to establish peaceful relations with the KR regime. But the KR leaders were intent on war. Behind this seeming insanity clearly lay the assumption that China would support the KR militarily in such a conflict.

Faced with growing Khmer Rouge belligerence, the Vietnamese leadership decided in early 1978 to support internal resistance to the Pol Pot regime, with the result that the Eastern Zone became a focus of insurrection. War hysteria reached bizarre levels within Democratic Kampuchea. In May 1978, on the eve of So Phim's Eastern Zone uprising, Radio Phnom Penh declared that if each Cambodian soldier killed thirty Vietnamese, only 2 million troops would be needed to eliminate the entire Vietnamese population of 50 million. It appears that the leadership in Phnom Penh was seized with immense territorial ambitions, i.e., to recover Kampuchea Krom, the Mekong Delta region, which they regarded as Khmer territory.

After the May 1978 revolt, the Khmer Rouge intensified massacres of people they perceived to be Vietnamese sympathizers in the Eastern Zone. In November, Vorn Vet led an unsuccessful coup d'état. There were now tens of thousands of Cambodian and Vietnamese exiles on Vietnamese territory.

On December 3, 1978, Radio Hanoi announced the formation of the Kampuchean United Front for National Salvation (KNUFNS). This was a heterogeneous group of communist and noncommunist exiles who shared an antipathy to the Pol Pot regime and a virtually total dependence on Vietnamese backing and protection. The KNUFNS provided the semblance, if not the reality, of legitimacy for Vietnam's invasion of Democratic Kampuchea and for its subsequent establishment of a satellite regime in Phnom Penh.

In the meantime, as 1978 wore on, Cambodian bellicosity in the border areas surpassed Hanoi's threshold of tolerance. Vietnamese policy makers opted for a military solution and, on December 22, Vietnam launched its offensive with the intent of overthrowing Democratic Kampuchea. A force of 120,000, consisting of combined armor and infantry units with strong artillery support, drove west into the level countryside of Cambodia's southeastern provinces. Together, the Vietnamese army and the National Salvation Front struck at the KR on December 25.

After a seventeen-day campaign, Phnom Penh fell to the advancing Vietnamese on January 7, 1979. Pol Pot and the main leaders initially took refuge near the border with Thailand. After making deals with several governments, they were able to use Thailand as a safe staging area for the construction and operation of new redoubts in the mountain and jungle fastness of Cambodia's periphery, Pol Pot and other Khmer Rouge leaders regrouped their units, issued a new call to arms, and reignited a stubborn insurgency against the regime in power as they had done in the late 1960s.

For the moment, however, the Vietnamese invasion had accomplished its purpose of deposing an unlamented and particularly violent dictatorship. A new administration of ex-Khmer Rouge fighters under the control of Hanoi was quickly established (who are ruling till present), and it set about competing, both domestically and internationally, with the Khmer Rouge as the legitimate government of Cambodia.

Peace still eluded the war-ravaged nation, however, and although the insurgency set in motion by the Khmer Rouge proved unable to topple the new Vietnamese-controlled regime in Phnom Penh, it did nonetheless keep the country in a permanent state of insecurity. The new administration was propped up by a substantial Vietnamese military force and civilian advisory effort.

As events in the 1980s progressed, the main preoccupations of the new regime were survival, restoring the economy, and combating the Khmer Rouge insurgency by military and by political means. The fostering of activity to meet these imperatives and the building of institutions are described in subsequent articles in the History of Cambodia series.

• Cambodian genocide denial
• Khmer Rouge Killing Fields
• The Killing Fields (film), British film drama
• First They Killed My Father by Loung Ung
• Mass killings under communist regimes

• Seng Ty: The Years of Zero: Coming of Age Under the Khmer Rouge
• Ben Kiernan: The Pol Pot Regime: Race, Power, and Genocide in Cambodia under the Khmer Rouge, 1975–79 Yale University Press; 2nd ed. ISBN 0-300-09649-6
• Jackson, Karl D. Cambodia: 1975–1978 Rendezvous with Death. Princeton: Princeton University Press, 1989
• Ponchaud, François. Cambodia: Year Zero. New York: Holt, Rinehart and Winston, 1978
• Michael Vickery: Cambodia 1975–1982 University of Washington Press; June 2000 ISBN 974-7100-81-9
• From Sideshow to Genocide: Stories from the Cambodian Holocaust – virtual history of the Khmer Rouge plus a collection of survivor stories.
• First They Killed My Father: A Daughter of Cambodia Remembers (HarperCollins Publishers, Inc., 2000) ISBN 0-06-019332-8
• Denise Affonço: To The End Of Hell: One Woman's Struggle to Survive Cambodia's Khmer Rouge. (With Introduction by Jon Swain); ISBN 978-0-9555729-5-1
• Ho, M. (1991). The Clay Marble. Farrar Straus Giroux. ISBN 978-0-374-41229-6
• Daniel Bultmann: Irrigating a Socialist Utopia: Disciplinary Space and Population Control under the Khmer Rouge, 1975–1979, Transcience, Volume 3, Issue 1 (2012), pp. 40–52 (Text-Link)
• Piergiorgio Pescali: "S-21 Nella prigione di Pol Pot". La Ponga Edizioni, Milan, 2015. ISBN 978-8897823308