The failure to establish contacts with Moscow did not weaken the position of Pol Pot, as he had Beijing and Hanoi behind him. To strengthen his support from Hanoi he even showed readiness for close union and “special solidarity” with the DRV: Pol Pot introduced Nuon Chea – a person trusted in Hanoi, whom Le Duan, leader of the Vietnamese communists, in a conversation with the Soviet ambassador, called a politician of “pro-Vietnam orientation” as the occupant of the second most important post in the party. Speaking of Nuon Chea, Le Duan literally emphasized “he is our man indeed and my personal friend" (Record of conversation of the Soviet ambassador with Le Duan, first secretary of the Vietnamese communist party Central Committee, RSAMH, Fund 5, inventory 69, file 2314, November 16, 1976, p. 113).
The compromise with Hanoi allowed Pol Pot to reserve to himself authority in the party leadership, to provide the material and military aid for fighting groups, which he called the Revolutionary Army. In the period 1968-1970 this army conducted unsuccessful operations against the forces of the ruling regime, sustaining heavy losses, and did not have the slightest hope of coming to power.A great chance for Pol Pot and Khmer communists came in March, 1970. Their long-term enemy - Cambodian leader prince Sihanouk - was overthrown in the military coup d’etat of March 18, 1970. He had to enter into a military-political union with the communists to get back to power. It became a turning point for the communists: in the eyes of thousands of peasants, they turned from enemies of Sihanouk into his protectors. The revolutionary army started growing as on yeast, and the mass base of the communists considerably increased. In this case the goals of purely communist reorganization obviously were set aside for the moment, and the slogans of protection of the legal chief of state and of national independence came to the fore.
In April-May 1970, significant North-Vietnamese forces entered Cambodia in response to the call for help addressed to Vietnam not by Pol Pot, but by his deputy Nuon Chea. Nguyen Co Thach recalls: “Nuon Chea has asked for help and we have liberated five provinces of Cambodia in ten days.” (RSAMH, Fund 5, inventory 75, file 1062. Information on the conversation of the German comrades with the deputy minister of foreign affairs of the SRV Nguyen Co Thach, who stayed on a rest in the GDR from the 1st to the 6th of August, 1978. August 17, 1978, p. 70). In 1970, in fact, Vietnamese forces occupied almost a quarter of the territory of Cambodia, and the zone of communist control grew several times, as power in the so-called liberated regions was given to the CPK. At that time relations between Pol Pot and the North Vietnamese leaders were especially warm,
In 1978, the then Deputy Minister of Foreign Affairs of Vietnam, Ngyuen Co Thach, told German communists that in 1974 Cambodians had asked for assistance for the purpose of taking Phnom Penh. “But the Chinese did not provide such aid, then Pol Pot had approached Vietnam”. The new call for assistance, as in 1970, did not come from Pol Pot himself, but from his deputy within the party, Nuon Chea (Record of conversation of the Deputy Minister of Foreign Affairs of the SRV, Ngyuen Co Thach, with German comrades while staying for rest in the GDR in August 1-6, 1978. RSAMH, Fund 5, inventory 75, file 1062, August 17, 1978, p. 72). There is nothing strange about Pol Pot’s compelled appeal to Vietnam for assistance. The strange thing was why the Vietnamese leadership, which was fully informed of the special position of the Khmer Rouge leader concerning relations with Hanoi, did not undertake any action to change the power pattern within the top ranks of the Communist Party to their own benefit. Apparently, the position of Nuon Chea, as the main person on whom Hanoi leaders put their stakes, proved to be decisive at that moment. Nuon Chea was already closely cooperating with Pol Pot. It was obvious that he consistently and consciously deceived the Vietnamese principals concerning the real plans of the Khmer leadership, pointing out the inexpediency of any replacement of the Khmer leader. As a result, in 1974 Vietnam granted military aid with no strings attached. Pol Pot was not toppled. There were not even attempts to shatter his positions or strengthen the influence of opposition forces. It is possible that Hanoi simply did not want undesirable problems in its relations with Phnom Penh at the moment of preparation for its own decisive assault in the South.There is no doubt that the apparent desire of the Khmer leadership’s majority to govern Cambodia independently and without external trusteeship, was obviously underestimated in Hanoi. Vietnamese leaders confessed to this blunder later. A member of the VWP Politbureau and a long-term Minister of Foreign Affairs, Ngyuen Co Thach, for instance, in his 1978 conversation with German communists, told them that “in 1975 Vietnam evaluated the situation in Cambodia incorrectly”