Pol Pot began to be placed in communal dining halls, while oil paintings and busts of him were produced. The cult was ultimately never implemented. The failure of Cambodian troops in the Eastern Zone to successfully resist the Vietnamese incursion made Pol Pot suspicious of their allegiances. He ordered a purge of the Eastern Zone, with over 400 CPK cadres from the area being sent to S-21. Aware that they would be killed on Pol Pot's orders, increasing numbers of Eastern Zone troops began rebelling against the Khmer Rouge government. Pol Pot sent more troops into the Eastern Zone to defeat the rebels, ordering them to slaughter the inhabitants of any villages that were believed to be harbouring any rebel forces. This suppression in the east was, according to Short, "the bloodiest single episode under Pol Pot's rule". Fleeing the government troops, many leading rebels—including Zone deputy chiefs Heng Samrin and Pol Saroeun—made it into Vietnam, where they joined the anti-Pol Pot exile community. By August 1978, Pol Pot could only consider Mok's forces in the south-west and Pauk's in the Central Zone as being reliable. Early in 1978, Pol Pot's government began trying to improve relations with various foreign countries, such as Thailand, to bolster its position against Vietnam. Many other governments in Southeast Asia sympathised with Cambodia's situation, fearing the impact of Vietnamese expansionism and Soviet influence on their own countries. Although supportive of the Cambodians, the Chinese government decided not to send its army into Cambodia, fearing that an all-out conflict with Vietnam could provoke a war with the Soviet Union. Meanwhile, Vietnam was planning its full-scale invasion of Cambodia. In December 1978, it formally launched the Khmer National United Front for National Salvation (KNUFNS), a group made up of Cambodian exiles which it hoped to install in place of the Khmer Rouge. Initially, KNUFNS was headed by Heng Samrin. Fearing this Vietnamese threat, Pol Pot wrote an anti-Vietnamese tract titled the Black Paper. In September 1978, Pol Pot began increasingly courting Sihanouk in the hope that the latter could prove a rallying point in support of the Khmer Rouge government. That same month, Pol Pot flew to China to meet with Deng. Deng condemned Vietnamese aggression but suggested that the Khmer Rouge had precipitated the conflict by being too radical in its policies and by allowing Cambodian troops to behave anarchically along the border with Vietnam.