Vietnam War
Ousting and assassination of Ngô Đình Diệm

The inept performance of the ARVN was exemplified by failed actions such as the Battle of Ấp Bắc on 2 January 1963, in which a band of Viet Cong won a battle against a much larger and better-equipped South Vietnamese force, many of whose officers seemed reluctant even to engage in combat. The South Vietnamese lost 83 soldiers and 5 US war helicopters, serving to ferry troops shot down by Vietcong forces, while the Vietcong lost only 18 soldiers. The ARVN forces were led by Diệm's most trusted general, Huỳnh Văn Cao. Cao was a Catholic, promoted due to religion and fidelity rather than skill, and his main job was to preserve his forces to stave off coups. Policymakers in Washington began to conclude Diệm was incapable of defeating the communists and might even make a deal with Ho Chi Minh. He seemed concerned only with fending off coups and had become paranoid after attempts in 1960 and 1962, which he partly attributed to US encouragement. As Robert F. Kennedy noted, "Diệm wouldn't make even the slightest concessions. He was difficult to reason with..." Historian James Gibson summed up the situation:

Strategic hamlets had failed... The South Vietnamese regime was incapable of winning the peasantry because of its class base among landlords. Indeed, there was no longer a 'regime' in the sense of a relatively stable political alliance and functioning bureaucracy. Instead, civil government and military operations had virtually ceased. The National Liberation Front had made great progress and was close to declaring provisional revolutionary governments in large areas.

Discontent with Diệm's policies exploded in May 1963, following the Huế Phật Đản shootings of 9 Buddhists protesting the ban on displaying the Buddhist flag on Vesak, Buddha's birthday. This resulted in mass protests -the Buddhist crisis - against discriminatory policies that gave privileges to Catholics over the Buddhist majority. Diệm's elder brother Ngô Đình Thục was the Archbishop of Huế and aggressively blurred the separation between church and state. Thuc's anniversary celebrations occurred shortly before Vesak had been bankrolled by the government, and Vatican flags were displayed prominently. There had been reports of Catholic paramilitaries demolishing Buddhist pagodas throughout Diệm's rule. Diệm refused to make concessions to the Buddhist majority or take responsibility for the deaths. On 21 August 1963, the ARVN Special Forces of Colonel Lê Quang Tung, loyal to Diệm's younger brother Ngô Đình Nhu, raided pagodas, causing widespread destruction and leaving a death toll into the hundreds.

US officials began discussing regime change during the middle of 1963. The United States Department of State wanted to encourage a coup, while the Pentagon favored Diệm. Chief among the proposed changes was removal of Diệm's younger brother Nhu, who controlled the secret police and special forces, and was seen as being behind the Buddhist repression and the architect of the Ngô family's rule. This proposal was conveyed to the US embassy in Saigon in Cable 243. The CIA contacted generals planning to remove Diệm, and told them the US would not oppose such a move, nor punish them by cutting off aid. Diệm was executed, along with his brother, on 2 November 1963. When Kennedy was informed, Maxwell Taylor remembered he "rushed from the room with a look of shock and dismay on his face." Kennedy had not anticipated Diệm's murder. The U.S. ambassador Henry Cabot Lodge, invited the coup leaders to the embassy and congratulated them. Lodge informed Kennedy that "the prospects now are for a shorter war". Kennedy wrote Lodge a letter congratulating him for "a fine job".

Following the coup, chaos ensued. Hanoi took advantage and increased its support for the guerrillas. South Vietnam entered extreme political instability, as one military government toppled another in quick succession. Increasingly, each new regime was viewed by the communists as a puppet of the Americans; whatever the failings of Diệm, his credentials as a nationalist had been impeccable. US advisors were embedded at every level of the South Vietnamese armed forces. They were however criticized for ignoring the political nature of the insurgency. The Kennedy administration sought to refocus US efforts on pacification – which in this case was defined as countering the growing threat of insurgency – and "winning the hearts and minds" of the population. Military leadership in Washington, however, was hostile to any role for U.S. advisors other than troop training. General Paul Harkins, the commander of U.S. forces in South Vietnam, confidently predicted victory by Christmas 1963. The CIA was less optimistic, however, warning that "the Viet Cong by and large retain de facto control of much of the countryside and have steadily increased the overall intensity of the effort".

Paramilitary officers from the CIA's Special Activities Division trained and led Hmong tribesmen in Laos and into Vietnam. The indigenous forces were in the tens of thousands and conducted direct action missions, led by paramilitary officers, against the Communist Pathet Lao forces and their North Vietnamese supporters. The CIA ran the Phoenix Program and participated in the Military Assistance Command, Vietnam – Studies and Observations Group (MAC-V SOG).
combination:repeat_prompt, startend:quotation