In 1961 the rapid increase of insurgency in the South Vietnamese countryside led President John F. Kennedy's administration to decide to increase United States support for the Diem regime. Some $US65 million in military equipment and $US136 million in economic aid were delivered that year, and by December 3,200 United States military personnel were in Vietnam. The United States Military Assistance Command, Vietnam (MACV) was formed under the command of General Paul D. Harkins in February 1962. The cornerstone of the counterinsurgency effort was the strategic hamlet program, which called for the consolidation of 14,000 villages of South Vietnam into 11,000 secure hamlets, each with its own houses, schools, wells, and watchtowers. The hamlets were intended to isolate guerrillas from the villages, their source of supplies and information, or, in Maoist terminology, to separate the fish from the sea in which they swim. The program had its problems, however, aside from the frequent attacks on the hamlets by guerrilla units. The self-defense units for the hamlets were often poorly trained, and support from the Army of the Republic of Vietnam ( ARVN--see Glossary) was inadequate. Corruption, favoritism, and the resentment of a growing number of peasants who were forcibly being forced to resettled plagued the program. It was estimated that of the 8,000 hamlets established, only 1,500 were viable.

In response to increased United States involvement, all communist armed units in the South were unified into a single People's Liberation Armed Force (PLAF) in 1961. These troops expanded in number from fewer than 3,000 in 1959 to more than 15,000 by 1961, most of whom were assigned to guerrilla units. Southerners trained in the North who infiltrated back into the South composed an important element of this force. Although they accounted numerically for only about 20 percent of the PLAF, they provided a well-trained nucleus for the movement and often served as officers or political cadres. By late 1962, the PLAF had achieved the capability to attack fixed positions with battalionsized forces. The NLF was also expanded to include 300,000 members and perhaps 1 million sympathizers by 1962. Land reform programs were begun in liberated areas, and by 1964 approximately 1.52 million hectares had been distributed to needy peasants, according to Communist records. In the early stages, only communal lands, uncultivated lands, or lands of absentee landlords were distributed. Despite local pressure for more aggressive land reform, the peasantry generally approved of the program, and it was an important factor in gaining support for the liberation movement in the countryside. In the cities, the Workers' Liberation Association of Vietnam (Hoi Lao Dong Giai Phong Mien Nam), a labor organization affiliated with the NLF, was established in 1961.

Diem grew steadily more unpopular as his regime became more repressive. His brother and chief adviser, Ngo Dinh Nhu, was identified by regime opponents as the source of many of the government's repressive measures. Harassment of Buddhist groups by ARVN forces in early 1963 led to a crisis situation in Saigon. On May 8, 1963, ARVN troops fired into a crowd of demonstrators protesting the Diem government's discriminatory policies toward Buddhists, killing nine persons. Hundreds of Buddhist bonzes responded by staging peaceful protest demonstrations and by fasting. In June a bonze set himself on fire in Saigon as a protest, and, by the end of the year, six more bonzes had committed self-immolation. On August 21, special forces under the command of Ngo Dinh Nhu raided the pagodas of the major cities, killing many bonzes and arresting thousands of others. Following demonstrations at Saigon University on August 24, an estimated 4,000 students were rounded up and jailed, and the universities of Saigon and Hue were closed. Outraged by the Diem regime's repressive policies, the Kennedy administration indicated to South Vietnamese military leaders that Washington would be willing to support a new military government. Diem and Nhu were assassinated in a military coup in early November, and General Duong Van Minh took over the government.

Data as of December 1987