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 month leading up to 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.
Background
General Nguyễn Khánh had come to power in January 1964 after surprising the ruling junta of General Dương Văn Minh in a pre-dawn operation, taking control without firing a shot. Because of American pressure, he retained the popular Minh as a token head of state, while holding the real power by controlling the Military Revolutionary Council (MRC). In August, the Vietnam War expanded with the Tonkin Gulf incident, a disputed encounter between North Vietnamese and American naval vessels; Washington accused the communists of launching an attack in international waters..
Khánh saw the tense situation as an opportunity to increase his power. On August 7, he declared a state of emergency, giving the police the ability to search properties under any circumstances, ban protests and arbitrarily jail "elements considered as dangerous to national security". He further enacted censorship to stop "the circulation of all publications, documents, and leaflets considered as harmful to public order". Khánh produced a new constitution, known as the Vũng Tàu Charter, which would have augmented his personal power at the expense of the already-limited Minh. However, this only served to weaken Khánh as large demonstrations and riots in the cities broke out—with the majority Buddhists prominent—calling for an end to the state of emergency and the new constitution, as well as a progression back to civilian rule.
Fearing he could be toppled by the intensifying protests, Khánh met with Buddhist leaders.. They asked him to repeal the new constitution, reinstate civilian rule, and remove Cần Lao Party—a secret Catholic body used by former President Ngô Đình Diệm to infiltrate and control all aspects of society—members from power, and Khánh agreed. General Trần Thiện Khiêm claimed "Khánh felt there was no choice but to accept since the influence of Trí Quang was so great that he could not only turn the majority of the people against the government but could influence the effectiveness of the armed forces." Khánh publicly promised to reformulate the Vũng Tàu Charter, allow protests and liberalize the press.. This encouraged more demonstrations by activists, and Khánh responded with wider concessions. Under the new arrangements, the new constitution would be repealed, and the MRC would disband. Khánh also promised to create an elected legislature within a year.
Many senior officers, particularly the Catholic Generals Khiêm and Nguyễn Văn Thiệu, decried what they viewed as a handing of power to the Buddhist leaders. They tried to remove Khánh in favor of Minh, and recruited many officers to their plot. Khiêm and Thieu sought out US Ambassador Maxwell Taylor for a private endorsement of their plan, but Taylor did not want any more changes in leadership, fearing a corrosive effect on the already-unstable government. This deterred Khiêm's group from acting on their plans..
The division among the generals came to a head at a meeting of the MRC on August 26–27. Khánh said the instability was due to troublemaking by members and supporters of the Catholic-aligned Đại Việt Quốc dân đảng (Nationalist Party of Greater Vietnam), whom he accused of putting partisan plotting ahead of the national interest. Prominent officers associated with the Đại Việt included Thieu and Khiêm. Khiêm blamed Khánh's weakness in dealing with Buddhist activists for the demonstrations in the cities and the rural losses to the communists.. Thieu and another Catholic General Nguyễn Hữu Có called for the replacement of Khánh with Minh, but the latter refused. Minh claimed that Khánh was the only one who would get funding from Washington, so they should support him, prompting Khiêm to angrily say "Obviously, Khánh is a puppet of the US government, and we are tired of being told by the Americans how we should run our internal affairs." Feeling pressured by the strong condemnations of his colleagues, Khánh promised to resign, but no replacement was agreed upon and another meeting was convened.
After more arguing between the senior officers, they agreed that Khánh, Minh, and Khiêm would rule as a triumvirate for two months, until a new civilian government could be formed. However, because of their disunity, the trio did little. Khánh dominated the decision-making and sidelined Khiêm and Minh. The US military commander in Vietnam William Westmoreland deplored the concessions Khánh made to political opponents and lobbied Washington for permission to attack North Vietnam, saying that Khánh could not survive without it.
Coup
At the start of September 1964, General Lâm Văn Phát was dismissed as Interior Minister, while General Dương Văn Đức was about to be removed as IV Corps commander. Both were removed partly due to pressure from Buddhist activists, who accused Khánh of accommodating too many Catholic Diệm supporters in leadership positions. Diệm had tried to use the loyalist Phát to help thwart the November 1963 coup, but the rebels managed to sideline Diệm's general and execute the president. Disgruntled by their demotions, Phát and Đức launched a coup attempt before dawn on September 13, having recruited ten army battalions. They gained the support of Colonel Lý Tòng Bá, the head of the 7th Division's armored section, and Colonel Dương Hiếu Nghĩa, a tank commander who had been one of Diệm's assassins.. It appeared at this stage that the coup was supported by Catholic and Đại Việt elements. Another member of the conspiracy was Colonel Phạm Ngọc Thảo, who while a Catholic, was a communist spy trying to maximize infighting at every possible opportunity.
Đức and Phát's plot was supported during the planning phase by Defense Minister and triumvirate member Khiêm. General Huỳnh Văn Cao, a Catholic and Diệm loyalist while the former president was alive, claimed in a 1972 newspaper interview that Khiêm—by then prime minister—had asked him to join the coup. Cao said he had declined Khiêm's invitation, mildly mocking him by asking "You're part of the 'Troika' now ... won't you be overthrowing yourself?" Cao said he had pointed out that political upheaval in Saigon would be a bad idea because Vietnam was prominent during the ongoing US presidential election campaign and negative publicity could lead to a decrease in American public and political support for South Vietnam..
Four battalions of rebel troops moved before dawn from the Mekong Delta towards Saigon, using armored personnel carriers and jeeps carrying machine guns. After cowing several police checkpoints on the edge of the capital with threats of machine-gun and artillery fire, the plotters put rebel sentries in their place to seal off Saigon from incoming or outgoing traffic. They then captured communication facilities in the capital, including the post office, to prevent messages from being sent in or out. As his troops took over the city, Phát sat in a civilian vehicle and placidly said "We'll be holding a press conference in town this afternoon at 4 p.m." He said "This is nothing to worry about. Just a little operation against some politicians." The rebels set up their command post in the Saigon home of General Duong Ngoc Lam, who had been removed from his post as Mayor of Saigon by Khánh. Lam had commanded the Civil Guard during Diệm's presidency and was one of his trusted supporters.
The rebels took over the city without any gunfire, and used the national radio station to make a broadcast. Claiming to represent "The Council for the Liberation of the Nation", Phát proclaimed a regime change, and accused Khánh of promoting conflict within the nation's military and political leadership. He promised to capture Khánh and pursue a policy of increased anti-communism, with a stronger government and military. Phát said he would use the ideology and legacy of Diệm to lay the foundation for his new junta. Đức claimed the coup attempt was prompted by "the transfer to the capital of some neutralist elements, and by some pro-communists in the government". According to the historian George McTurnan Kahin, Phát's broadcast was "triumphant" and may have prompted senior officers who were neither part of the original conspiracy nor fully loyal to Khánh to conclude that Phát and Đức would not embrace them if they abandoned Khánh..