Editing Khmer Rouge (section)

==== War with Vietnam ====
{{main|Cambodian–Vietnamese War}}
[[File:Thảm sát.jpg|thumb|Photo images of the [[Ba Chúc massacre]] at a Vietnamese museum, as the massacre was one of the events that prompted the 1978 Vietnamese invasion of Kampuchea]]
Fearing that Vietnam would attack Cambodia, Pol Pot ordered a pre-emptive invasion of Vietnam on 18 April 1978. His Khmer Rouge forces crossed the border and looted nearby villages, mostly in the border town of [[Ba Chúc]]. Of the 3,157 civilians who had lived in Ba Chúc,<ref>[http://www.iht.com/articles/2004/01/07/edpringle_ed3_.php "Meanwhile: When the Khmer Rouge came to kill in Vietnam"] {{Webarchive|url=https://web.archive.org/web/20051027063937/http://www.iht.com/articles/2004/01/07/edpringle_ed3_.php |date=27 October 2005 }}. International Herald Tribune.</ref> [[Ba Chúc massacre|only two survived the massacre]]. These Khmer Rouge forces were repelled by the Vietnamese.<ref name="Morris2">{{cite book|title=Why Vietnam Invaded Cambodia: Political Culture and the Causes of War|url=https://books.google.com/books?id=uEYKCGj6J0wC|first=Stephen J.|last=Morris|publisher=Stanford University Press|date=1 January 1999|isbn=0804730490|pages=25, 32, 93–97, 102–04, 107, 111, 159}}</ref>

After several years of border conflict and after a flood of refugees fled from Kampuchea, relations between Kampuchea and Vietnam collapsed by December 1978. On 25 December 1978, the Vietnamese armed forces along with the [[Kampuchean United Front for National Salvation]], an organization founded by Heng Samrin that included many dissatisfied former Khmer Rouge members,<ref name="Vickery 1999" /> invaded Cambodia and captured Phnom Penh on 7 January 1979. Despite a traditional Cambodian fear of Vietnamese domination, defecting Khmer Rouge activists assisted the Vietnamese and with Vietnam's approval, they became the core of the new People's Republic of Kampuchea. The new government was quickly dismissed as a "[[Puppet state|puppet government]]" by the Khmer Rouge and China.<ref name="Morris2" />

At the same time, the Khmer Rouge retreated west and it continued to control certain areas near the Thai border for the next decade.<ref>Bultmann Daniel (2015). ''Inside Cambodian Insurgency. A Sociological Perspective on Civil Wars and Conflict''. Ashgate: Burlington, Vermont; Farnham, England. {{ISBN|978-1472443076}}.</ref> These included [[Phnom Malai]], the mountainous areas near [[Pailin]] in the [[Cardamom Mountains]] and [[Anlong Veng]] in the [[Dângrêk Mountains]].<ref name="Cook 2017" /> These Khmer Rouge bases were not self-sufficient and were funded by diamond and timber smuggling, military assistance from China channeled by means of the Thai military, and food smuggled from markets across the border in Thailand.<ref>Fawthrop, Tom; Jarvis, Helen (2014). ''Getting Away With Genocide?''. {{ISBN|0-86840-904-9}}.</ref>