As Americans pause to mark the 50th anniversary of the assassination of President John F. Kennedy, they should not overlook the other fateful assassination that took place that same month. On November 2, 1963, South Vietnam’s President Ngo Dinh Diem was murdered in Saigon in a coup carried out by a group of generals operating with the tacit approval of the U.S. government.

Historians agree that the coup marked a turning point in America’s involvement in Vietnam. The coup was the hinge by which U.S. policy swung from nation building to military intervention, from limited support for the Diem regime to a new role of propping up weak military governments, and from an advisory role to a more active one that eventually led to a U.S. takeover of the war.

The importance of the coup as a turning point in Vietnam has provoked a long-running debate about who on the American side was responsible for it and why U.S. leaders thought it was a risk worth taking to topple the established government in that country. Some still view it as a standard Cold War coup undertaken independently by the CIA. Others blame President Kennedy for allowing it to go forward, while still others place the blame on subordinates in Saigon who pressed the military to eliminate Diem without consulting the White House. Like other important events of that era, the assassination of Diem remains shrouded in controversy.

Tapes of White House conversations now available through the Kennedy library in Boston and recently released documents from the State Department provide the information needed to answer most of these questions. The assassination and overthrow of Diem was the culmination of a two-year clash within the Kennedy administration between officials who thought the war could be won with conventional tactics (supporters of Diem) and those who advocated a coup as an opening for a new strategy of counterinsurgency. Kennedy followed developments in Saigon until the eleventh hour and chose not to oppose the coup. The episode foreshadowed a strategic debate that would continue within the U.S. government throughout the Vietnam conflict and in some respects continues to this day.

In 1961, the Bureau of Intelligence and Research in the State Department, led by Roger Hilsman with the support of senior officials George Ball and Averell Harriman, began to issue reports that called Diem’s leadership into question. These reports claimed that Diem was too unpopular and autocratic to head a government whose mission was to win the support of the people of South Vietnam. By early 1962, these advisers were pressing for a counterinsurgency strategy in opposition to the conventional strategy supported by the Pentagon.

The conventional strategy focused on blocking infiltration routes and supply lines and protecting key assets, such as major cities, military bases, and transportation routes. The counterinsurgency strategy emphasized intelligence operations to identify Communist infrastructure and the use of American advisers to help the Diem government win support among the peasants through “strategic hamlets,” a program designed to deliver services to peasants while isolating them from Communist insurgents.

The clash between the two approaches was rooted in different conceptions of the war. The proponents of conventional tactics, including Secretary of Defense Robert McNamara and head of the CIA John McCone, saw it as an invasion supported and supplied by North Vietnam. Diem, agreeing with this assessment, wanted to attack North Vietnam while delaying political reform until the war was won. The proponents of counter-insurgency saw the conflict as a domestic insurrection caused by the unpopularity and lack of inclusiveness of the Diem government. The only way to defeat the insurgency, they argued, was to win the “hearts and minds” of the peasants by creating a government they could support. Diem was both ineffective and unpopular—and thus they concluded that he had to go.

Kennedy supported the alliance with Diem because he saw no popular alternative. Vice President Lyndon Johnson, though reluctant to join the debate, was also in this camp. Diem had been something of a hero to the nationalist cause in South Vietnam because of his role in opposing the French and establishing an independent national government. Though corrupt and authoritarian in his methods and a Catholic in a country with a majority Buddhist population, Diem had standing that no other potential leader could claim. For this reason, Kennedy was reluctant to throw him over for an untested alternative.

The situation changed markedly in 1963 with a series of military reverses in the Mekong Delta early in the year and an uprising by Buddhist opponents of the regime beginning in April and May and continuing through the summer months. The military reverses showed the Army of the Republic of Vietnam to be ineffective, even with the aid of U.S. advisers and equipment, while the Buddhist uprising indicated that support for the Diem government was collapsing. The crisis fed into the political debate within the Kennedy administration and led to a succession of reports about what might happen in the case of resignation, assassination, or a coup against the Diem government. In June, Kennedy appointed Henry Cabot Lodge, his old political adversary from Massachusetts, as the new U.S. ambassador to South Vietnam, with instructions to take a tougher line with the Diem regime.

Diem may have sealed his fate by launching a series of brutal raids on Buddhist pagodas on August 21, just before Lodge’s arrival. Those raids resulted in the arrests of more than 1,400 Buddhist opponents of the regime, with several score more missing or presumed dead. The raids coincided with new reports pointing to a deteriorating military situation.

At this point, the lines were drawn between Hilsman, Ball, and Harriman (with Lodge on the ground in Saigon) urging removal of Diem and McNamara, McCone, and Gen. Maxwell Taylor (chairman of the Joint Chiefs of Staff) doubting the wisdom of a coup and the ability of the generals in Saigon to pull it off. Kennedy, seeking to break the impasse, sent McNamara and Taylor to Saigon. The two men returned with a gloomy assessment of the war and a recommendation to exert pressure on Diem through gradual reductions in U.S. aid. As Lodge began to impose these cuts, word spread in Vietnam that the U.S. support for the Diem government was being withdrawn. With these steps the United States moved into the final phase of its nine-year partnership with Diem.

Kennedy loyalists over the years have claimed that the president was unaware of plans for a coup and never authorized it. But the documentary sources and tapes of White House conversations show that the president was informed about plans for the coup and participated in discussions and debates with advisers until the last minute. At a White House meeting on October 29, with all key advisers present, Kennedy said, “We have been rather more negative for a coup, but it is clear from [Lodge’s] answers that he is for a coup for what he thinks are very good reasons. He is playing a stronger part there than we are playing here, and I admire his nerve but not his prudence.” Later in that meeting, when discussing last-minute instructions for Lodge, the president said, “Let’s see what we can get [from Lodge]. Let’s put it all on Cabot.” Kennedy seemed willing to let Lodge make the call, which the ambassador was more than willing to do.

On November 1, the South Vietnamese Army moved; Diem and his brother, Ngo Dinh Nhu, were shot the next morning after surrendering. Though dismayed by the deaths of Diem and Nhu and no doubt harboring doubts about the wisdom of the coup, Kennedy nevertheless sent a congratulatory cable to Lodge: “Your own leadership in pulling together and directing the whole American operation in South Vietnam in recent months has been of the greatest importance, and you should know that this achievement is recognized here throughout the Government.”

The overthrow of Diem did not work out as planned. The anti-Diem coup was the first of many, as one military faction replaced another. Between 1963 and 1965, there were 12 different military governments in Saigon. If the purpose was to create a popular government capable of implementing a counterinsurgency strategy, then the coup was a manifest failure.

No one could have foreseen on November 1 that President Kennedy would be assassinated three weeks later and replaced by a vice president who had been outspoken in opposition to the coup. Johnson saw it as the outcome of an undisciplined decision-making process in which junior figures in the administration maneuvered to bring about a change in policy. As president, he moved quickly to centralize in the White House all decisions about the war; the State Department faction was immediately cut out of that process. Johnson placed his trust in senior figures, like McNamara and McCone, who had opposed the coup and viewed the conflict within a conventional framework.

The weakness of successive military governments in South Vietnam was a key factor that led to the introduction of 500,000 U.S. ground troops, and the sustained air campaign against North Vietnam. The United States would go on to wage a conventional war, relying on firepower and ground operations, the interdiction of infiltration routes and supply lines, the attrition of Communist manpower, body counts, air raids against the North, and other measures inherited from campaigns on battlefields in Europe.

It is impossible to know how Kennedy would have handled the deteriorating situation. One point is certain: Diem, had he not been overthrown, would not have permitted a U.S. intervention on the scale it eventually reached by 1967. In that sense, Diem’s death may have been a more important factor in the broadening U.S. involvement than Kennedy’s.

The advocates of counterinsurgency in the Kennedy administration failed to consider whether the U.S. Army was capable of implementing such a strategy in the conditions that then prevailed. As Andrew Krepinevich Jr. argues in The Army and Vietnam, conventional modes of military strategy were embedded in Army operations by virtue of the types of wars the United States had waged previously. The U.S. Army fought a conventional war in Vietnam because it was the kind of war it knew how to fight. The advocates of the coup were wrong to think that toppling Diem was the key to implementing a counterinsurgency strategy.

The overthrow of Diem was a prelude to America’s large-scale intervention in Vietnam. The episode was a primer containing lessons that U.S. policymakers would relearn in the decades to follow: that toppling governments in the developing world breeds instability, revolution, and civil war; that it is difficult to promote democratic reform using the carrots and sticks of U.S. aid; and that counterinsurgency, even if it could be capably implemented, is not a sure recipe for military success. After five decades, the “other assassination” in 1963 still contains lessons well worth remembering.

William Piereson works as a private consultant in foreign affairs in Washington.

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