Harry Truman

Harry Truman emerges in the book as the president whose decisions moved the United States from an unsettled response to the Soviet atomic test into a sustained thermonuclear arms buildup. His choices were shaped not only by assessments of weapons and military risk but also by domestic political pressure and a governing climate in which secrecy constrained public discussion. In the account of J. Robert Oppenheimer’s career, Truman’s decisions establish the policy stakes behind Oppenheimer’s increasingly consequential dissent.

The Soviet test and the lost opening

When the Soviet Union secretly detonated an atomic bomb on August 29, 1949, radioactive material collected by an American reconnaissance plane supplied evidence of the explosion. A panel of experts, including J. Robert Oppenheimer, spent five hours examining the findings on September 19 and concluded that the evidence was overwhelming: Joe-1 was an atomic bomb, closely copied from the Manhattan Project plutonium design. The result meant that the American atomic monopoly had ended, a development Oppenheimer had long expected.

The next day, David Lilienthal briefed Truman and urged an immediate announcement. Truman remained skeptical that the Soviets possessed a real bomb and chose to wait several days. Oppenheimer, hearing of the delay, was incredulous: he believed the United States was missing an opportunity to seize the initiative. When Truman finally announced that an atomic explosion had occurred in the Soviet Union, he stopped short of calling it a bomb. The hesitation contrasts with the panel’s technical conclusion and with Oppenheimer’s hope that acknowledging the new reality might reopen efforts toward international control of nuclear technology.

That hope did not govern the immediate response. Within days, Truman endorsed a Joint Chiefs proposal to increase weapons production. A stockpile that had stood at about fifty bombs in June 1948 was projected to reach roughly three hundred by June 1950. Lewis Strauss argued that American military superiority would inevitably diminish and pressed for a technological leap: a crash program to develop the thermonuclear Super. Truman had not been aware of that possibility until October 1949, but once informed, he was intrigued by it. The Soviet test thus became not merely a fact to acknowledge but a spur to a wider competition in weapons and production.

The decision to pursue the Super

The case against a thermonuclear crash program was both strategic and moral. Oppenheimer and the General Advisory Committee warned that a weapon potentially yielding 100 million tons of TNT could destroy hundreds of square miles and could not be confined to the destruction of military installations. Their report argued that such a weapon might become an instrument of genocide, and that its existence in the American arsenal could damage U.S. security by making other nations believe America contemplated catastrophe. The committee also maintained that a large stock of atomic weapons could provide retaliation comparable to a Super, while smaller tactical weapons and stronger conventional forces might offer a more credible defense against a Soviet invasion.

Oppenheimer carried that argument to legislators even though he knew his views were unwelcome. He said that if the Soviets had the weapon and the United States did not, the country would be badly off, but that both countries would still be badly off if both possessed it. The point, he argued, was that developing the weapon would accelerate Soviet development. The debate reached its decisive point on January 31, 1950, when David Lilienthal, Dean Acheson, and Defense Secretary Louis Johnson met Truman at the White House. Lilienthal was still opposed to a crash program; Acheson privately shared many of his objections but believed domestic politics would make delay intolerable. Johnson’s stated concern was to protect the president.

In the Oval Office, Truman cut off Lilienthal’s presentation with a direct question: “Can the Russians do it?” When the others agreed that they could, Truman said, “In that case, we have no choice. We’ll go ahead.” Lilienthal recorded that Truman had decided before the meeting began. The exchange reduced a disputed question about long-term security, escalation, and moral consequence to the immediate test of whether the Soviet Union could build the weapon. Lilienthal later compared the seven-minute encounter to saying no to a steamroller.

That evening Truman announced a program to determine the “technical feasibility of a thermonuclear weapon” and ordered a broad review of American strategy. The resulting NSC-68, largely produced by Paul Nitze, depicted the Soviet Union as bent on world conquest and called for a rapid, sustained increase in the political, economic, and military strength of the free world. Circulated in April 1950, it rejected George F. Kennan’s proposal for a no-first-use policy. A large nuclear arsenal became a foundation of U.S. defense strategy, and Truman authorized an industrial program to expand the production of warheads in all configurations.

Secrecy, scale, and strategic consequences

Truman’s decision was accompanied by a demand for silence. David Lilienthal told Oppenheimer that Truman had required the scientists involved to refrain from discussing the decision publicly. Disheartened, Oppenheimer considered resigning from the General Advisory Committee; he and James Conant ultimately stayed, reasoning that public debate over a settled decision might not be responsible. Conant later regretted not resigning. The imposed silence mattered because it kept the public from weighing the arguments that had been made inside government, while leaving the official decision to define the direction of policy.

The scale of the buildup that followed gave the decision a reach far beyond the initial feasibility program. By the end of the decade, the American stockpile would grow from about 300 warheads to nearly 18,000. Over the next five decades, the United States would produce more than 70,000 nuclear weapons and spend $5.5 trillion on nuclear weapons programs. The book presents the January 1950 choice as a turning point in the Cold War arms race, not simply as a technical research decision. George F. Kennan was disgusted by the outcome, while Isidor Isaac Rabi later said, “I never forgave Truman.”

Truman and Oppenheimer’s policy conflict

The dispute over the Super sharpened the divide between Truman’s administration and Oppenheimer, who feared that a weapon thousands of times more destructive than an atomic bomb would intensify the arms race and make indiscriminate killing central to military planning. Oppenheimer’s opposition was not a claim that the Soviet threat did not exist. He accepted that the Soviets could develop the weapon; he challenged the assumption that matching them would make the United States safer. His alternative emphasized limits, arms control, and a force sized for specific defensive purposes rather than an ever-expanding stockpile.

The consequences reached beyond the policy debate. In 1951, Oppenheimer was appalled by an Air Force plan to obliterate Soviet cities on a scale he described as a scheme of criminal genocide. He also argued in the Project Vista report for prioritizing tactical weapons over city-destroying thermonuclear bombs, a position that could itself make nuclear use more likely. His evolving proposals were therefore neither free of strategic risk nor reducible to simple opposition to nuclear weapons. They placed him in conflict with military planners and with advocates of the Super, while exposing the difficulty of separating deterrence from the possibility of escalation.

The book also situates the later assault on Oppenheimer within a broader climate of anticommunist suspicion. In 1946, FBI chief J. Edgar Hoover investigated numerous Truman administration officials associated with atomic policy, including John J. McCloy and Dean Acheson, and circulated allegations based on purported informants. The episode is presented as a prelude to the use of communist associations to silence political opponents, not as evidence that Truman directed the investigation. In 1953, the Atomic Energy Commission’s formal charges against Oppenheimer combined old allegations about his associations with a new accusation that his opposition had slowed hydrogen-bomb development. By then, policy dissent had become part of the case against him.

Truman’s role in this account is therefore consequential but not uncomplicated: he faced a genuine change in the strategic balance, yet chose a response that magnified the arms race and narrowed the space for public argument. His decision made the Super a national undertaking; the secrecy surrounding that choice helped define the conditions under which Oppenheimer’s warnings, and eventually his professional standing, would be judged.