National Army of Democratic Kampuchea The National Army of Democratic Kampuchea ( NADK ) was a Cambodia n guerrilla force . NADK were the armed forces of the Party of Democratic Kampuchea ( also known as ' Khmer Rouge ' ) , operating between 1979 and the late 1990s . History . NADK was formed in December 1979 in order to replace the Revolutionary Army of Kampuchea . NADK forces consisted mainly of former RAK troops - large numbers of whom had escaped the 1978 to 1979 Vietnamese invasion of Cambodia . It included as well as conscripts coerced into submission during the RAK retreat and new volunteers or recruits either pressed into service during in - country raids or drawn from among refugee groups . The New York Times reported in June 1987 that " the Khmer Rouge army is believed to be having some success in its recruitment , not only among the refugees in its camps but within the Vietnamese controlled People ' s Republic of Kampuchea . " The NADK did not make personnel figures public , but estimates by military observers and by journalists generally ranged between 40 , 000 and 50 , 000 combatants in the 1980s . In 1987 the opinion that the NADK was " the only effective fighting force " opposing the Vietnamese was more often expressed by Western observers . In an interview published in the United States in May 1987 , Norodom Sihanouk reportedly said , " without the Khmer Rouge , we have no credibility on the battlefield . . . [ they are ] . . . the only credible military force . " During the 1980s , the Khmer Rouge leadership , composed of party cadres who doubled as military commanders , remained fairly constant . Pol Pot retained an ambiguous but presumably prominent position in the hierarchy , although he was nominally replaced as commander in chief of the NADK by Son Sen , who like Pol Pot had also been a student in Paris and who had gone underground with him in 1963 . There were reports of factions in the NADK , such as one loyal to Khieu Samphan , prime minister of the defunct regime of Democratic Kampuchea , and his deputy Ieng Sary , and another identified with Pol Pot and Ta Mok ( the Southwestern Zone commander who conducted extensive purges of party ranks in Cambodia in 1977 to 1978 ) . Although led by party and military veterans , the NADK combatants in 1987 were reportedly " less experienced , less motivated , and younger " than those the Vietnamese had faced in previous encounters . Nevertheless , the new Khmer Rouge recruits still were " hardy and lower class , " and tougher than the non - communist combatants . During forays into Cambodia , NADK units employed terror tactics against Khmer civilians , including murder and destruction of economic resources . Such success as they achieved in recruiting was apparently owed to traditional Cambodian hatred of the Vietnamese invader , although there were reports that some of the peasantry would have preferred to endure a continued Vietnamese occupation rather than to suffer a return to Khmer Rouge rule . During this time the Khmer Rouge divided the country into four military zones that functioned virtually autonomously under their respective commanders . Within these four zones , three areas — the provinces around the Tonle Sap , the western border of Cambodia , and the remainder of the country — were sites of NADK tactical operations . It was the first area , the heartland of Cambodia , that the NADK viewed as the " Achilles ' heel of the Vietnamese enemy , " where NADK military efforts were concentrated . NADK units managed to keep the main routes linking Phnom Penh to western Cambodia " in a permanent state of insecurity , " according to a senior Vietnamese military observer ; traffic to and from the seaport of Kampong Saom was obliged to move in convoys . Both highways and railroads from the capital were interdicted intermittently because of guerrilla activity . Officials in Phnom Penh told a Western correspondent in 1987 that the Khmer Rouge were then operating in small insurgent groups inside Cambodia in a battle for the villages , rather than fighting from the Thai border area , as had been the case prior to the 1984 to 1985 Vietnamese dry - season offensive . In carrying the war to the countryside , the NADK demonstrated that it had gone on the strategic defensive , that is , that it would adhere to a doctrine of guerrilla warfare until the balance of forces was about equal . If this parity were to achieved , NADK strategists presumably would then switch to offensive operations . In carrying on its protracted insurgency , the NADK received the bulk of its military equipment and financing from China , which had supported the previous regime of Democratic Kampuchea . One pro - Beijing source put the level of Chinese aid to the NADK at US $ 1 million a month . Another source , although it did not give a breakdown , set the total level of Chinese assistance , to all the resistance factions , at somewhere between US $ 60 million and US $ 100 million a year . The Chinese weaponry observed in the possession of NADK combatants included AK - 47 assault rifles , RPD light machine guns , RPG launchers , recoilless rifle s , and anti - personnel mine s . NADK guerrillas usually were seen garbed in dark green Chinese fatigues and soft " Mao caps " without insignia . No markings or patches were evident on guerrilla uniforms , although the NADK had promulgated a hierarchy of ranks with distinctive insignias in 1981 . To keep troops and supplies moving into the combat zone , the NADK , according to Vietnamese sources , followed two infiltration routes . One of them ran south from Thailand through the Dangrek Escarpment into Cambodia . The second ran north from Trat , a minor Thai seaport that may have been an unloading point for Chinese supplies for the Khmer Rouge . In spite of substantial Chinese material assistance , however , the NADK could not maintain the logistical supply line needed to conduct a sustained military campaign . NADK continued fighting Cambodian government forces into the late 1990s .