As the Buddhist crisis deepened in July 1963, non-communist Vietnamese nationalists and the military began preparations for a coup.
Bùi Diễm, later South Vietnam's Ambassador to the United States, reported in his memoirs that General Lê Văn Kim requested his aid in learning what the United States might do about Diệm's government.
Diễm had contacts in both the embassy and with the high-profile American journalists then in South Vietnam, David Halberstam (New York Times), Neil Sheehan (United Press International), and Malcolm Browne (Associated Press).

The coup d'état was designed by a military revolutionary council including ARVN generals led by General Dương Văn Minh.
Lieutenant Colonel Lucien Conein, a CIA officer, had become a liaison between the US Embassy and the generals, who were led by Trần Văn Đôn.
They met each other for the first time on 2 October 1963 at Tân Sơn Nhất airport.
Three days later, Conein met with General Dương Văn Minh to discuss the coup and the stance of the US towards it.
Conein then delivered the White House's message of American non-intervention, which was reiterated by Henry Cabot Lodge Jr., the US ambassador, who gave secret assurances to the generals that the United States would not interfere.

The coup was chiefly planned by the Vietnamese generals.
Unlike the coup in 1960, the plotters of the 1963 coup knew how to gain broad support from other ARVN officer corps.
They obtained the support of General Tôn Thất Định, General Đỗ Cao Trí, General Nguyễn Khánh, and the I Corps and II Corps Commanders.
Only General Huỳnh Văn Cao of IV Corps remained loyal to Diệm.

On 1 November 1963, Conein donned his military uniform and stuffed three million Vietnamese piastres into a bag to be given to General Minh.
Conein then called the CIA station and gave a signal indicating that the planned coup against President Diem was about to start.
 Minh and his co-conspirators swiftly overthrew the government.
With only the palace guard remaining to defend Diệm and his younger brother Nhu, the generals called the palace offering Diệm exile if he surrendered.
That evening, however, Diệm and his entourage escaped via an underground passage to Cha Tam Catholic Church in Cholon, where they were captured the following morning.
On 2 November 1963, the brothers were assassinated together in the back of an M113 armoured personnel carrier with a bayonet and revolver by Captain Nguyễn Văn Nhung, under orders from Minh given while en route to the Vietnamese Joint General Staff headquarters.
Diệm was buried in an unmarked grave in a cemetery next to the house of the US Ambassador.
As the Buddhist crisis deepened in July 1963, non-communist Vietnamese nationalists and the military began preparations for a coup. Bùi Diễm, later South Vietnam's Ambassador to the United States, reported in his memoirs that General Lê Văn Kim requested his aid in learning what the United States might do about Diệm's government. Diễm had contacts in both the embassy and with the high-profile American journalists then in South Vietnam, David Halberstam (New York Times), Neil Sheehan (United Press International), and Malcolm Browne (Associated Press).
The coup d'état was designed by a military revolutionary council including ARVN generals led by General Dương Văn Minh. Lieutenant Colonel Lucien Conein, a CIA officer, had become a liaison between the US Embassy and the generals, who were led by Trần Văn Đôn. They met each other for the first time on 2 October 1963 at Tân Sơn Nhất airport. Three days later, Conein met with General Dương Văn Minh to discuss the coup and the stance of the US towards it. Conein then delivered the White House's message of American non-intervention, which was reiterated by Henry Cabot Lodge Jr., the US ambassador, who gave secret assurances to the generals that the United States would not interfere.
The coup was chiefly planned by the Vietnamese generals. Unlike the coup in 1960, the plotters of the 1963 coup knew how to gain broad support from other ARVN officer corps. They obtained the support of General Tôn Thất Định, General Đỗ Cao Trí, General Nguyễn Khánh, and the I Corps and II Corps Commanders. Only General Huỳnh Văn Cao of IV Corps remained loyal to Diệm.
On 1 November 1963, Conein donned his military uniform and stuffed three million Vietnamese piastres into a bag to be given to General Minh. Conein then called the CIA station and gave a signal indicating that the planned coup against President Diem was about to start.  Minh and his co-conspirators swiftly overthrew the government. With only the palace guard remaining to defend Diệm and his younger brother Nhu, the generals called the palace offering Diệm exile if he surrendered. That evening, however, Diệm and his entourage escaped via an underground passage to Cha Tam Catholic Church in Cholon, where they were captured the following morning. On 2 November 1963, the brothers were assassinated together in the back of an M113 armoured personnel carrier with a bayonet and revolver by Captain Nguyễn Văn Nhung, under orders from Minh given while en route to the Vietnamese Joint General Staff headquarters. Diệm was buried in an unmarked grave in a cemetery next to the house of the US Ambassador.
Ngo Dinh Diem