September 1964 South Vietnamese coup attempt

The September 1964 South Vietnamese coup attempt took place before dawn on September 13, 1964, when the ruling military junta of South Vietnam, led by General Nguyễn Khánh, was threatened by a coup attempt headed by Generals Lâm Văn Phát and Dương Văn Đức, who sent dissident units into the capital Saigon. They captured various key points and announced over national radio the overthrow of the incumbent regime. With the help of the Americans, Khánh was able to rally support and the coup collapsed the next morning without any casualties.

In the immediate month leading up the coup, Khánh's leadership had become increasingly troubled. He had tried to augment his powers by declaring a state of emergency, but this only provoked large-scale protests and riots calling for an end to military rule, with Buddhist activists at the forefront. Fearful of losing power, Khánh began making concessions to the protesters and promised democracy in the near future. He also removed several military officials closely linked to the discriminatory Catholic rule of the slain former President Ngô Đình Diệm; this response to Buddhist pressure dismayed several Catholic officers, who made a few abortive moves to remove him from power.

In part because of pressure from Buddhist protests, Khánh removed the Catholics Phát and Đức from the posts of Interior Minister and IV Corps commander, respectively. They responded with a coup supported by the Catholic-aligned Đại Việt Quốc dân đảng, as well as General Trần Thiện Khiêm, a Catholic who had helped Khánh to power. Having captured the radio station, Phát then made a broadcast promising to revive Diệm's policies. Khánh managed to evade capture and, during the first stage of the coup, there was little activity as most senior officers failed to support either side. Throughout the day, Khánh gradually rallied more allies and the U.S. remained supportive of his rule and pressured the rebels to give up. With the backing of Air Marshal Nguyễn Cao Kỳ, commander of the Republic of Vietnam Air Force, and General Nguyễn Chánh Thi, Khánh was able to force Phát and Đức to capitulate the next morning, September 14. Đức, Kỳ and Thi then appeared at a media conference where they denied that any coup had taken place and put on a choreographed display of unity, claiming that nobody would be prosecuted over the events.

Convinced that Khiêm was involved in the plot, Khánh had him exiled to Washington as ambassador, and eased General Dương Văn Minh out of the political scene, thereby removing the other two nominal members of the ruling triumvirate. However, concerned that Kỳ and Thi had become too powerful, Khánh had Phát and Đức acquitted at their military trial in an attempt to use them as political counterweights. Despite his survival, the coup was seen by the historian George McTurnan Kahin as the start of Khánh's ultimate political decline. Due to the intervention of Kỳ and Thi, Khánh was now indebted to them, and in an attempt to maintain his power in the face of increasing military opposition, he tried to court support from Buddhist civilian activists, who supported negotiations with the communists to end the Vietnam War. As the Americans were strongly opposed to such policies, relations with Khánh became increasingly strained and he was deposed in February 1965 with US connivance.