In June 1982, at an event in Kuala Lumpur, the Khmer Rouge were among the factions declaring the formation of a Coalition Government of Democratic Kampuchea (CGDK) as an alternative to the administration in Phnom Penh. On the ground in Cambodia there nevertheless remained little military collaboration between these factions, which included the Khmer Rouge as well as the Sihanoukist National Army and Son Senn's National Front for the Liberation of the Khmer People. In 1983, Pol Pot travelled to Bangkok for a medical check-up; there he was diagnosed with Hodgkin's disease. In mid-1984, Office 131 was moved to a new base further into Cambodia, near the O'Suosaday river. In December, the Vietnamese Army launched a major offensive, overrunning the Khmer Rouge's Cambodian base and pushing Pol Pot back into Thailand. There, he established a new base, K-18, several miles outside Trat.