Roger Hilsman, director of the State Department Bureau of Intelligence and Research, sends a memorandum to Secretary of State Dean Rusk pointing out that the communist Viet Cong fighters are obviously prepared for a long struggle.
While government control of the countryside had improved slightly, the Viet Cong had expanded considerably in size and influence, both through its own efforts and because of its attraction to "increasingly frustrated non-communist, anti-Diem elements." According to Hilsman, successfully eradicating the Viet Cong would take several years of greater effort by both the United States and the South Vietnamese government of President Ngo Dinh Diem. Real success, he noted, depended upon Diem gaining the support of the South Vietnamese people through social and military measures, which he had so far failed to implement. Hilsman felt that a noncommunist coup against Diem "could occur at any time," and would seriously disrupt or reverse counterinsurgency momentum. As it turned out, Hilsman was eventually proven correct. On November 1, 1963, dissident South Vietnamese generals led a coup resulting in the murder of Diem. His death marked the end of civilian authority and political stability in South Vietnam. The succession of military juntas, coups, and attempted coups in 1964 and early 1965 weakened the government severely and disrupted the momentum of the counterinsurgency effort against the Viet Cong.