The Communist Party of Kampuchea turned against the Soviet Union

The Communist Party of Kampuchea turned against the Soviet Union after Stalin died. In The Black Papers, one of their few public documents, they said:

"During the stay of the delegation of the Communist Party of Kampuchea in Hanoi, Le Duan wanted to induce the Communist Party of Kampuchea to establish relations with the Communist Party of the Soviet Union. He reported that the Soviet Ambassador to Hanoi would like to meet the delegation of the Communist Party of Kampuchea to invite it to pay a visit to Moscow.
The delegation of the Communist Party of Kampuchea told Le Duan that the Communist Party of Kampuchea did not oppose the Soviet Union. Its tasks consisted only of achieving its objective which was to lead Kampuchea’s revolution to victory. It did not want to interfere in the China-Soviet difference. But the Soviet Union has shown its hostility towards the Communist Party of Kampuchea. Indeed, in 1964, the Soviet Embassy in Phnom Penh strove to set up in Kampuchea another communist party and charged the Communist Party of Kampuchea with being an inefficient Party and of having an absurd line. The communist party that the Soviet Union wanted to set up should have been made of on the one hand the renegades at the time of the struggle against the French colonialists, such as Siv Heng and Pen Youth who became intelligence agents in the Lon No! clique’s pay and on the other hand the students from the Khmero-Sovietique Technical Institute in Phnom Penh. But in the end, that party could not come to life for lack of people’s support. Concerning the meeting that the Soviet Ambassador was asking for, the delegation of the Communist Party of Kampuchea answered that it would be better to postpone it."