In December, Vietnam sent 50,000 troops over the border along a 100-mile stretch, penetrating 12 miles into Cambodia. Cambodia then formally broke off diplomatic relations with Vietnam. Cambodian forces fought back against the invaders, who had withdrawn to Vietnam by 6 January 1978. At this point, Pol Pot ordered Cambodia's military to take an aggressive, proactive stance, attacking Vietnamese troops before the latter had the chance to act. In January and February 1978, the Cambodian Army launched raids on various Vietnamese villages. The Vietnamese Politburo then concluded that it must not leave Pol Pot in power, but must remove him from power before the Cambodian military strengthened further. In 1978, it established military training camps for Cambodian refugees in southern Vietnam, forming the nucleus of a future Cambodian regime. The Cambodian government also readied itself for war. Plans for a personality cult revolving around Pol Pot were drawn up, based on the Chinese and North Korean models, in the belief that such a cult would unify the population in wartime. Large photographs of 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.