The Fall of Phnom Penh and the Fall of Saigon in April 1975 immediately brought a new conflict between Vietnam and Cambodia. Although the North Vietnamese and the Khmer Rouge had previously fought side by side, the leaders of the newly created Democratic Kampuchea continued to view Vietnam with great suspicion, because they believed the Vietnamese communists had never given up their dream of creating an Indochinese federation with Vietnam as the leader. For that reason, the Kampuchean government removed all North Vietnamese military forces from Kampuchean territory shortly after their capture of Phnom Penh on 17 April 1975. In the first major clash between the two former allies, the Kampuchean Revolutionary Army (KRA) invaded the Vietnamese island of Phú Quốc on 1 May 1975 (barely 24 hours after Saigon fell), claiming it was part of Kampuchea's territory.