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November/December 2018

The Absolute Weapon: The Nuclear Option in Vietnam
Photo: National Archives and Records Administration (NARA)


Presidential historian Michael Beschloss attracted a lot of attention this fall writing in his book Presidents of War about Operation Plan Fracture Jaw, a project to deploy tactical nuclear weapons in South Vietnam. But the atomic bomb, or the “absolute weapon” as it was first called, has a larger place in the war’s history.

Until the early 1950s the U.S. nuclear stockpile was so small—and the weapons themselves so bulky—that all nukes were strategic weapons. But in 1952 the Mark VII atomic bomb became available, with power similar to the one dropped on Nagasaki and light enough to be carried by tactical aircraft. The Navy took this ticket into the nuclear age, and from then on American planners paid steady attention to tactical nukes.

In March 1954 French troops were under siege at Dien Bien Phu. As the situation worsened, the French asked for American help. In that context, the U.S. considered conducting a top secret bombing operation called Operation Vulture. One variant was to have Mark VII atomic bombs delivered from U.S. aircraft carriers in the South China Sea. The ships were redeployed, as were some of the explosive cages that triggered the Mark VII. A Pentagon study determined that three nuclear weapons dropped in a triangular pattern around Dien Bien Phu would be optimal for destroying the Vietnamese forces.

A lesson plan taught at the Navy special weapons course at Coronado beginning in 1954 appears to have adapted this exact plan, providing that French defenders deepen their entrenchments and hunker down just before weapons dropped. Air Force Chief of Staff Gen. Nathan F. Twining later mused, “You could take all day to drop a bomb, make sure you put it in the right place . . . and clean those commies out of there and the band could play The Marseillaise and the French could come marching out in great shape.”

Another possibility was to lend nuclear weapons to the French. Georges Bidault, the French foreign minister, wrote in his memoirs that Secretary of State John Foster Dulles had asked him what he’d do if Washington offered two bombs. Americans denied it, but there is evidence the French cabinet discussed how to respond, and a few months after the battle other French diplomats who had worked with Bidault referred to it. There also is evidence that President Eisenhower, at a meeting on April 30, 1954, speculated about giving the French a few atomic weapons. This was against the law, as a marginal note on the meeting record stated.    

Eisenhower had ended the Korean War but had not prepared for another land war in Asia. There was no intervention. Dien Bien Phu fell on May 7, 1954. The chief of naval operations, Adm. Arthur F. Radford, who had favored bombing, speculated later, when weapons designers came up with early versions of the neutron bomb (which minimized blast effects while enhancing radiation), that if he had had such weapons for Operation Vulture he could really have done something.

Adm. Felix D. Stump, commander-in-chief in the Pacific in 1963, had been one of the carrier group commanders at Dien Bien Phu. On a later visit to Saigon he met with South Vietnamese leader Ngo Dinh Diem, and Stump asked Diem if he thought dropping the bomb would have been a good idea. Diem replied, “Yes, that would have been wise.”  

Presidential Nuclear Recommendations

Eisenhower continued to believe in tactical nuclear weapons in Indochina. He referred to Dien Bien Phu again in a 1961 interview. In May 1962, when a Laotian crisis led President John Kennedy to consider military moves, Eisenhower told a Kennedy emissary that the U.S. should use nuclear weapons if needed. Something similar happened after Lyndon Johnson became president. LBJ began Operation Rolling Thunder in February 1965. On February 17 he had Ike at the White House to give his views on Vietnam. Eisenhower hypothesized the U.S. could avert Russian or Chinese intervention by threatening nuclear weapons.

Meanwhile, Washington saw the war in conventional military terms—and Eisenhower had encouraged the view that tactical nukes should be considered conventional weapons. That hindered proper responses to guerrilla warfare. In early 1957 a RAND war game called “Vietnam-3” had a scenario in which North Vietnam invaded the South across the DMZ and from Laos. In a campaign of twenty-six game days, the NVA were repelled with 33,000 dead, using thirty-four tactical nuclear weapons.

Kennedy officials staged a similar war game, again played at RAND, featuring a scenario in which 310,000 North Vietnamese and Laotian troops invaded Thailand and South Vietnam. After thirty game days the war ended in communist defeat, with 45 percent theoretical losses. Nuclear weapons were used to cut the passes along the Vietnamese-Laotian border and to destroy forests, trapping enemy armies. Some 208 tactical nukes were detonated. (There is no data on how analysts projected environmental consequences.) This game ended with the NVA still in the field, undefeated. Analysts later criticized these RAND games for rigidity—not permitting the North Vietnamese to react to U.S. moves—and estimated the games exaggerated the effects on the adversary.

War games are one thing. Policy is another. In 1964-65 the Johnson administration was making decisions that committed Americans to a ground war. Among top officials, Undersecretary of State George Ball has gained fame as one who foresaw dire consequences from intervention. Though much has been written about Ball’s dissent, this has never been covered: He squarely confronted the nuclear issue. Ball maintained that as ground fighting dragged on, American forces would take substantial casualties and that, “at this point, we should certainly expect mounting pressure for the use of at least tactical nuclear weapons.”

Ball argued that U.S. nukes on Asians would incur a huge political cost, confirming charges of racism in the original use of atomic bombs on Japan. Use would also emphasize Russian virtue (Moscow had never resorted to these weapons), would carry specific costs in various countries (such as Japan), and “the first firing of a nuclear weapon (whether tactical or strategic, it makes no difference) would revive a real but latent guilt sense in many Americans… discouragement and a profound sense of distrust.” Ball also warned of possible Russian and Chinese intervention that could escalate to full-scale nuclear war.

Johnson didn’t take Ball’s advice to avoid an American war, but he paid attention on nukes. Ball’s boss, Secretary of State Dean Rusk, asserted in his memoirs that “We never seriously considered using nuclear weapons in Vietnam.” It would have been impossible to control radioactive fallout, Rusk wrote, drifting to Japan and the Philippines, not to mention China and Russia—again raising the possibility of their intervention.

Secretary of Defense Robert McNamara wrote that his own worries began with a Joint Chiefs of Staff proposal in January 1964. “Beginning then—and throughout the next four years—I was determined to minimize the risk that U.S. military action in Indochina would draw Chinese or Soviet ground or air forces into confrontation with the United States,” he wrote, “whether with conventional or nuclear forces, either in Asia or elsewhere. President Johnson held the same view.” That was the opposite of Eisenhower’s position.

Throughout this period, the war gamers were still at it. In 1964 more sophisticated simulations took place at the Research Analysis Corporation. These substantiated a study for the Army called Oregon Trail. This game featured a hypothetical island, but the contenders and capabilities mimicked U.S. and Vietnamese sides. The postmortem concluded: “The ability of the [U.S.] division to accomplish its mop-up operation with nuclear weapons was not impressive.”

Studying Possible Nuclear Strikes

Nevertheless, in the corridors of the Pentagon it was often argued that a few nukes would stop infiltration down the Ho Chi Minh Trail. Physicist Freeman Dyson, a Nobel laureate, undertook the most detailed nuclear study we know. In 1966 Dyson had sat through too many Pentagon belly-thumping sessions. When an official blithely spoke of lobbing in a nuke just to keep the other side guessing, Dyson had had enough.

A leading member of a group called JASON—scientists who used their summer vacations to help the Pentagon solve defense problems—Dyson put nukes in Vietnam on the table. The 1966 JASON summer study received Pentagon approval in the late winter. It was finalized at a scientific meeting outside Boston.

The six-week study was carried out at the University of California, Santa Barbara, in July and August. There were three studies that year: one creating a technological barrier to infiltration along the DMZ and across Laos (the McNamara line), and another on the effectiveness of Rolling Thunder. A third, on the nuclear weapons question, was conducted by Dyson, Robert Gomer and S. Courtenay Wright of the University of Chicago, and Steven Weinberg, then at Harvard. The study was formally administered by the Institute for Defense Analysis, another think tank, and resulted in a report titled “Tactical Nuclear Weapons in Southeast Asia.”

The study investigated three elements: the advantages of using tactical weapons; the vulnerability of American troops to such weapons; and the potential for nuclear weapons in the hands of insurgents. Pentagon planners had focused on the advantages to American forces, but those supposed advantages were far less than imagined.

Standard physics and radiation calculations showed that many circumstances rendered nuclear weapons ineffective. For one thing, area coverage against enemy troops in the jungle would consume large numbers of weapons. Strikes at defined locations, such as the tunnel systems in War Zones C and D, required localization of targets by scout patrols just before weapons use. Shutting the passes on the Ho Chi Minh Trail would necessitate repeated strikes—on the order of three thousand per year.

Expending such numbers in Vietnam would deplete the stockpile in the face of the Soviet threat to NATO. A more reasonable effort would affect the adversary only about as much as an increase in the B-52 Arc Light effort—exactly the course the U.S. adopted.

Even worse, JASON found that Americans in South Vietnam were themselves appallingly vulnerable to enemy strikes with nuclear munitions. Dyson and his cohorts found U.S. troops tightly packed in thirteen main bases, plus one that mostly handled naval forces. Excepting Saigon (the weapon requirements for which remain classified), neutralizing all these required forty-five to sixty nukes of a size plentiful in Soviet inventories. And there were multiple possible delivery methods, ranging from missile attack to air raid or even guerrilla strike.

Unlike Viet Cong and NVA targets hidden in the jungle, the American bases were in the open and well-defined. In short, the U.S. stood to lose more than it could gain. The Dyson study also noted that the introduction of these munitions could very possibly lead to other insurgent forces in other wars using them as well—also clearly not in American interests.

All the JASON studies were briefed in August-September 1966, first to the scientists, then to Assistant Secretary of Defense John T. McNaughton, then to McNamara. McNaughton was unhappy about the Rolling Thunder study. Participants do not recall him saying anything about nukes. McNamara turned the tables, saying he had already read the reports. He asked questions about the infiltration barrier. “I have no way of knowing whether anybody ever read our report,” Dyson said.

Pressured to Act

However, the memorandum that McNamara sent to Johnson on May 19, 1967, has more direct evidence. Coming amid new MACV requests for massive reinforcements, McNamara responded to Johnson’s demand to know how the troops would be used if he sent them. Arguing against escalation, McNamara said that the increase would drive demands to take the lid off: “The use of tactical nuclear and area-denial-radiological-bacteriological-chemical weapons would probably be suggested if the Chinese entered the war in Vietnam or Korea or if U.S. losses were running high while conventional efforts were not producing desired results.”

McNamara’s words proved prophetic. Although Johnson rejected the big troop increases, he felt the pressures anyway. The 1968 Tet Offensive was one of those periods when U.S. losses ran high. At Khe Sanh, American Marines, some special operations troops, and ARVN rangers were in a siege situation that resembled Dien Bien Phu. A declassified cable from Joint Chiefs of Staff Chairman Gen. Earle Wheeler to Gen. William Westmoreland asked for his opinion on the efficacy of using tactical nuclear weapons at Khe Sanh.

Westmoreland’s memoir claims the cable resulted from LBJ’s inquiries, but there is no evidence for that. In fact, the evidence refutes that claim, as Beschloss shows. On February 3, 1968, Westmoreland cabled that nuclear weapons should be considered if the situation around Khe Sanh and the DMZ got much worse. National Security Adviser Walt Rostow told LBJ that nuclear planning had begun. A Westmoreland dispatch on February 10 approved a secret operation called Fracture Jaw.

Tom Johnson, LBJ’s note-taker and confidant, recalled the president as “extraordinarily upset” by this, according to Beschloss. Johnson quashed the move. On February 9 he had Secretary Rusk say before the Senate Foreign Relations Committee that in Vietnam there were no weapons stockpiles or plans for their use.

On February 12 Gen. Wheeler ordered a standdown of all Fracture Jaw preparations, with everyone sworn to silence. The White House put out a press statement that Johnson had received no such recommendations. On the 16th LBJ told a news conference that presidents make all decisions on nuclear weapons deployment.

Instead of using nuclear weapons, Johnson began the Paris Peace Talks. His successor, Richard M. Nixon, however, came the closest since Eisenhower to opening the nuclear Pandora’s box. Nixon’s moves were closely tied to his search for military options. The first instance came in 1969, with Nixon’s strenuous efforts to pressure Hanoi. Plans prepared at the Pentagon, according to a March 2 memorandum to National Security Adviser Henry Kissinger, included “Appendix E,” which was described as “A plan for actual or feigned technical escalation of [the] war against the North (nuclear).”

“Go For Broke”

Nixon’s July 1969 strategy conference aboard the presidential yacht Sequoia left him determined to “go for broke,” as he wrote in his memoir. At the negotiations Kissinger threatened the North Vietnamese in their very first secret meeting on August 4, 1969. This formed part of a concerted strategy. As Nixon put it to Chief of Staff H.R. Haldeman, “I call it the Madman Theory, Bob. I want the North Vietnamese to believe I’ve reached the point where I might do anything to stop the war.”

The military planned a renewed bombing campaign against North Vietnam under the codename Pruning Knife. The White House used the name Duck Hook. Some of Kissinger’s subordinates recall discussions about using the absolute weapon.

At the eleventh hour, Nixon abandoned his concept for an offensive and appealed for public support of his war strategy. But Nixon simultaneously ordered a worldwide alert of U.S. nuclear forces. Nuclear bombers (B-52s) were stood down from training to generate the maximum alert force, while communications and other military movements were designed to ensure the Soviets would detect them. Since the only signals Nixon were sending were about the Vietnam War, the conclusion would be that the U.S. wanted to act there.

The evidence suggests that the October 1969 nuclear alert was, in effect, an effort to reap results anticipated from the abortive Duck Hook. This threat was the closest the U.S. had come since Vulture to brandishing nuclear weapons in Vietnam.

Observer and commentator Eqbal Ahmad said that North Vietnamese officials told him that by November 1972 Kissinger had threatened them with nuclear weapons thirteen times. In 1972 Hanoi conducted its Easter Offensive. Nixon resumed bombing the North as part of his response. But the president always saw his generals as not venturesome enough.

In the Oval Office on April 25, talking to Kissinger, Nixon made a typical demand for stronger action. “We’ve got to quit thinking in terms of a three-day strike,” Nixon said. Kissinger agreed. A couple of hours later, Nixon wanted to bomb dikes in North Vietnam. Then he said, “I’d rather use the nuclear bomb.” Nixon reassured Kissinger that he’d only been trying to get him to think big, but there it was, and with Nixon you never knew.

Actions were expanded, including bombing and mining Haiphong harbor. After his resignation Nixon told David Frost that four times during his presidency he had considered using nuclear weapons and that one of them had been at this critical moment.

The factors that had restrained LBJ on nukes still operated. Vietnam remained a limited war precisely because certain restrictions were observed, among them refusal to resort to nukes. An escalation so immense carried inherent potential for triggering intervention. Nixon had achieved some success decoupling Moscow and Beijing from Hanoi. He would have risked throwing all that away.

“Whenever we boxed the compass of all conceivable lines of action, the so-called nuclear option was occasionally on the list,” Rusk later wrote. “Researchers coming across such documents delight in such lights and inevitably blow them out of proportion. Despite the enormous costs and frustrations of Vietnam, the Kennedy, Johnson, and Nixon administrations chose to fight that war with conventional weapons and eventually lost the war rather than ‘win’ it with nuclear weapons.”

John Prados is a senior fellow of the National Security Archive and director of its Vietnam Documentation Project. He is the author of thirty books, including five on the Vietnam War, among them Vietnam: The History of an Unwinnable War, 1945-1975 (Kansas University Press).





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