The Geneva Agreements were viewed with doubt and dissatisfaction on all sides. Concern over possible United States intervention, should the Geneva talks fail, was probably a major factor in Hanoi's decision to accept the compromise agreement. The United States had dissociated itself from the final declaration, although it had stated that it would refrain from the threat or use of force to disturb the agreements. President Dwight D. Eisenhower wrote to the new Prime Minister of the Bao Dai government, Ngo Dinh Diem, in September 1954 promising United States support for a noncommunist Vietnam. Direct United States aid to South Vietnam began in January 1955, and American advisors began arriving the following month to train South Vietnamese army troops. By early 1955, Diem had consolidated his control by moving against lawless elements in the Saigon area and by suppressing the religious sects in the Mekong Delta. He also launched a "denounce the communists" campaign, in which, according to communist accounts, 25,000 communist sympathizers were arrested and more than 1,000 killed. In August 1955, Diem issued a statement formally refusing to participate in consultations with the DRV, which had been called for by the Geneva Agreement to prepare for national elections. In October, he easily defeated Bao Dai in a seriously tainted referendum and became president of the new Republic of Vietnam.

Despite the growing likelihood that national elections would not be held, the communist leadership in Hanoi decided for the time being to continue to concentrate its efforts on the political struggle. Several factors led to this decision, including the weakness of the party apparatus in the South, the need to concentrate on strengthening the war-weakened North, and pressure from the communist leadership of the Soviet Union, which, under General Secretary Nikita Khrushchev, had inaugurated its policy of peaceful coexistence with the West. By 1957, however, a shift to a more militant approach to the reunification of the country was apparent. Partly in response to Diem's anticommunist campaign, the Party stepped up terrorist activities in the South, assassinating several hundred officials of the Diem government. This led to the arrest of another 65,000 suspected Communists and the killing of more than 2,000 by the Saigon government in 1957. Repression by the Diem regime led to the rise of armed rebel self-defense units in various parts of the South, with the units often operating on their own without any party direction. Observing that a potential revolutionary situation had been created by popular resentment of the Diem government and fearing that the government's anticommunist policy would destroy or weaken party organization in the South, the VWP leadership determined that the time had come to resort to violent struggle.

Data as of December 1987