South Vietnamese Coup (1963)

As a result of the continuing civil war in South Vietnam, the Ngo Dinh Diem regime began raids and attacks on Buddhist temples. This resulted in a reaction from the Buddhists known as the Buddhist crisis. This crisis brought much unwanted press coverage to the oppressive regime of Ngo and ultimately forced the Kennedy administration to authorize a "regime change".

Nhu escalates; U.S. government conveys last warnings to Diem
On August 21, Nhu used the authority of martial law to carry out massive raids on Buddhist pagodas and portrayed those attacks as the responsibility of the ARVN and the CIA. However, the raids were not by ARVN forces at all, but by paramilitary police and Vietnamese Special Forces under the direct command of Le Quang Tung. This prompted key U.S. decisions, expressed in "Cable 243" from Assistant Secretary of State Roger Hilsman, conveying the Administration position to Ambassador Lodge. Hilsman's cable included the points:
 * "US Government cannot tolerate situation when such power lies in Nhu's hands. Diem must be given the chance to rid himself of Nhu and his coterie and replace them with the best military and polite personalities available
 * If, in spite of all your efforts, Diem remains obdurate and refuses, we must face the possibility that Diem himself cannot be preserved.

Hilsman made it clear that the Administration was insistent that the blame be placed on Nhu, that the ARVN be cleansed of taint, and the Nhus must go. The Nhu-must-go message was presented again and again, by different emissaries, with no results.

McNamara suggested sending an investigator, and, on September 6, MG Victor Krulak, JCS Special Assistant for Counterinsurgency and Special Activities. Joseph Mendenhall, a career diplomat, with him. their report of the Krulak-Mendenhall mission  generated a legendary response from the President. "You two did visit the same country, didn't you?"

On September 12, the National Security Council told Ambassador Lodge to reopen "tough" negotiations with Diem... Robert Kennedy speculated that if the war can be won neither with Diem nor in the event of a disruptive coup, a U.S. a U.S. disengagement should be considered. Robert Kennedy's perspective is representative of the Kennedy administration's position of not making a highly visible U.S. commitment to South Vietnam, in contrast to the situation where the Johnson administration kept escalating, for fear of the political repercussions of "losing".

A brief positive note came when South Vietnam ended martial law on the 16th. The next day, the NSC decided to escalate pressure on Diem, and not agree to Diem and Nhu staying as a team. Both for fact-finding and pressure, the NSC decided to send Secretary McNamara and General Taylor there on the "fact-gathering" McNamara-Taylor mission. In their first meeting with Ambassador Lodge and General Harkins, on the 25th, it was immediately obvious the Embassy and MACV had quite different perceptions.

After more meetings, the two senior officials returned and briefed the NSC on October 2nd. Their report was a military-civilian compromise, confirming military progress but warning of political instability. Greater GVN effort, they believed, was needed in both clear-and-hold operations and securing strategic hamlets. They recommended pressuring Diem by withdrawing 1,000 troops, selectively withholding general aid, and ending all support for the Vietnamese Special Forces (i.e., that carried out the pagoda raids). While McNamara and Taylor recommend against a coup, they did recommend identifying and cultivating alternative leadership. Kennedy approved their recommendations.

On the same day, CIA officer Conein "accidentally" met General Don, who tells him that a coup is nearly ready; the corps commander for the Saigon area had not yet committed. They schedule another meeting for the 5th.

At that meeting, Conein, with Lodge's approval, met with Gen. Duong Van Minh, the potential coup leader. He mentioned three possible plans; one involved assassination. Conein was noncommittal, but, when he reported back to Lodge, Lodge asked Washington that Conein "be authorized to say that the U.S. will not thwart a coup, that we are willing to review plans, and that we will continue support to a successor regime."