Editing Khmer Rouge (section)

=== Internal power struggles and purges ===
[[Hou Yuon]] was one of the first senior leaders to be purged. The Khmer Rouge originally reported that he had been killed in the final battles for Phnom Penh, but he was apparently executed in late 1975 or early 1976.<ref name="Becker 1998" />{{rp|202}} In late 1975, numerous Cambodian intellectuals, professionals and students returned from overseas to support the revolution. These returnees were treated with suspicion and made to undergo reeducation, while some were sent straight to [[Tuol Sleng]].<ref name="Becker 1998" />{{rp|272}} In 1976, the center announced the start of the socialist revolution and ordered the elimination of class enemies. This resulted in the expulsion and execution of numerous people within the party and army who were deemed to be of the wrong class.<ref name="Becker 1998" />{{rp|265}} In mid-1976, Ieng Thirith, minister of social affairs, inspected the northwestern zone. On her return to Phnom Penh, she reported that the zone's cadres were deliberately disobeying orders from the center, blaming enemy agents who were trying to undermine the revolution.<ref name="Becker 1998" />{{rp|236}} During 1976, troops formerly from the eastern zone demanded the right to marry without the party's approval. They were arrested and under interrogation implicated their commander who then implicated eastern zone cadres who were arrested and executed.<ref name="Becker 1998" />{{rp|264}}

In September 1976, Keo Meas, who had been tasked with writing a history of the party, was arrested as a result of disputes over the foundation date of the party and its reliance on Vietnamese support. Under torture at Tuol Sleng, he confessed that the date chosen was part of a plot to undermine the party's legitimacy and was then executed.<ref name="Becker 1998" />{{rp|268–9}} In late 1976, with the Kampuchean economy underperforming, Pol Pot ordered a purge of the ministry of commerce, and [[Khoy Thoun]] and his subordinates who he had brought from the northern zone were arrested and tortured before being executed at Tuol Sleng.<ref name="Becker 1998" />{{rp|221}} Khoy Thoun confessed to having been recruited by the CIA in 1958.<ref name="Becker 1998" />{{rp|282}} The center also ordered troops from the eastern and central zones to purge the northern zone killing or arresting numerous cadres.<ref name="Becker 1998" />{{rp|264–5}}

At the end of 1976, following disappointing rice harvests in the northwestern zone, the party center ordered a purge of the zone. Troops from the western and southwestern zones were ordered into the northwestern zone.  Over the next year, troops killed at least 40 senior cadre and numerous lower ranking leaders.<ref name="Becker 1998" />{{rp|238–40}}

The chaos caused by this purge allowed many Khmers to escape the zone and try to seek refuge in Thailand, but was met with gunfire by the Thai army, who then raped the Khmer women and children while they were hiding near the border with their families. The [[United Nations Border Relief Operation]] (UNBRO) on January 1, 1982, intervened to coordinate humanitarian assistance to Cambodian displaced persons along the [[Cambodia–Thailand border|Thai-Cambodian border]].<ref name="Becker 1998" />{{rp|308}}

In 1977, the center began purging the returnees, sending 148 to Tuol Sleng and continuing a purge of the ministry of foreign affairs where many returnees and intellectuals were suspected of spying for foreign powers.<ref name="Becker 1998" />{{rp|274–5}} In January, the center ordered eastern and southeastern zone troops to conduct cross-border raids into Vietnam. In March 1977, the center ordered [[So Phim]], the eastern zone commander, to send his troops to the border; however, with class warfare purges underway in the eastern zone, many units staged a mutiny and fled into Vietnam. Among the troops defecting in this period was [[Hun Sen]].<ref name="Becker 1998" />{{rp|304–5}} On 10 April 1977 [[Hu Nim]] and his wife were arrested. After three months of interrogation at Tuol Sleng, he confessed to working with the CIA to undermine the revolution following which he and his wife were executed.<ref name="Becker 1998" />{{rp|275–6}} In July 1977, Pol Pot and Duch sent So Phim a list of "traitors" in the eastern zone, many of whom were So Phim's trusted subordinates. So Phim disputed the list and refused to execute those listed, for the center this implicated So Phim as a traitor.<ref name="Becker 1998" />{{rp|306}} In October 1977, in order to secure the Thai border while focusing on confrontation with Vietnam, [[Nhim Ros]], the northwestern zone leader, was blamed for clashes on the Thai border, acting on behalf of both the Vietnamese and the CIA.<ref name="Becker 1998" />{{rp|305}}

In December 1977, the Vietnamese launched a punitive attack into eastern Cambodia, quickly routing the eastern zone troops including [[Heng Samrin]]'s Division 4 and further convincing Pol Pot of So Phim's treachery. [[Son Sen]] was sent to the eastern zone with center zone troops to aid the defense. In January 1978, following the Vietnamese withdrawal, a purge of the eastern zone began. In March, So Phim called a secret meeting of his closest subordinates advising them that those who had been purged were not traitors and warning them to be wary. During the next month more than 400 eastern zone cadres were sent to Tuol Sleng while two eastern zone division commanders were replaced. During May eastern zone military leaders were called to meetings where they were arrested or killed. So Phim was called to a meeting by Son Sen but refused to attend, instead sending four messengers who failed to return. On 25 May, Son Sen sent two brigades of troops to attack the eastern zone and capture So Phim. Unable to believe he was being purged, So Phim went into hiding and attempted to contact Pol Pot by radio. A meeting was arranged, but instead of Pol Pot, a group of center soldiers arrived, and So Phim committed suicide and the soldiers then killed his family.<ref name="Becker 1998" />{{rp|311–2}}

Many of the surviving eastern zone leaders fled into the forests where they hid from and fought center zone troops. In October 1978, [[Chea Sim]] led a group of 300 people across the border into Vietnam, and the Vietnamese then launched a raid into the eastern zone that allowed Heng Samrin and his group of 2,000 to 3,000 soldiers and followers to seek refuge in Vietnam. Meanwhile, the center decided that the entire eastern zone was full of traitors and embarked on a large scale purge of the area, with over 10,000 killed by July 1978, while thousands were evacuated to other zones to prevent them from defecting to the Vietnamese. The center also stepped up purges nationwide, killing cadres and their families, "old people" and eastern zone evacuees who were regarded as having dubious loyalty.<ref name="Becker 1998" />{{rp|312–4}}

In September 1978, a purge of the ministry of industry was begun, and in November Pol Pot ordered the arrest of [[Vorn Vet]], the deputy premier for the economy, followed by his supporters. Vorn Vet had previously served as the secretary of the zone around Phnom Penh, had established the Santebal and been Duch's immediate superior. Under torture, Vorn Vet admitted to being an agent of the CIA and the Vietnamese. Unable to reach the borders, ministry of industry personnel who could escape the purge went into hiding in Phnom Penh.<ref name="Becker 1998" />{{rp|324–5}}