In essence, Hanoi decided to begin actively sup¬porting a rebellion in Cambodia, using the native Cambodian Communist Party. The decision provided for a large-scale increase in the number of Khmer infiltrators from North Vietnam, and the start of guerrilla warfare in the Cambodian countryside. Above all, the policy was designed to be carried out covertly, and in such a way that Hanoi could plausibly disavow it. The obvious reason for secrecy was that an overt Communist insurrection in Cambodia was at odds with the Viet Cong need to keep their Cambodian bases open and the arms flowing from Sihanoukville. Three reasons fyave been advanced to ex¬plain their involvement.