The KPLC
On 1 February 1948, the Issarak movement formed the Khmer Peoples Liberation Committee with Chhuon as its president. Five of its eleven leaders were sympathetic to the Vietnamese, which pushed away certain elements of the Issarak movement. Though Chhuon was nominally anti-communist, the organisation also had two important Viet Minh supporters: Sieu Heng, who was head of the ICP North-Western branch, and his nephew Long Bunruot, who later changed his name to Nuon Chea and rose to become deputy leader of the Communist Party of Kampuchea (CPK), second only to Pol Pot.
By this time the Viet Minh was leading a concerted attempt to foster Issarak anti-colonialism and to turn it into support for communism in general, and Vietnamese communism in particular. This was especially the case on the eastern side of the country, where guerrilla cells were often commanded by Vietnamese, and Cambodian recruits into them often attended ICP political schools. There they were taught Marxist-Leninism and the virtues of cooperating with Vietnam. On the other side of the country, Son Ngoc Minh had returned from Thailand with enough weapons to equip a fairly large company. In 1947 he established the Liberation Committee of South-West Kampuchea (this is particularly of note, because by the end of the civil war of 1970-75 the south-west had one of the most powerful and well organised communist armies in Cambodia, and which would form the main core of Pol Pot's support). By late 1948 many areas of the country were under the effective control of powerful Issarak organisations.
By 1949, however, the Issarak movement in this form was coming to an end: the French began to exploit the greed of some Issarak leaders by giving them colonial positions, while others went off to join more radical organisations. Chhuon's KPLC expelled Sieu Heng and the majority of the other leftists, and remodelled itself as the Khmer National Liberation Committee, with Prince Chantaraingsey as its military commander. Tou Samouth and the other leftist Issaraks formed the United Issarak Front, which had heavy Vietnamese involvement. Chhuon went over to the French, while Chantaraingsey eventually left the KNLC and aligned with the right-wing, anti-monarchical Khmer nationalists, the Khmer Serai, under Son Ngoc Thanh.
Read more about this topic: Khmer Issarak