The Nuclear Age and the Risk of Nuclear War

The Nuclear Age and the Risk of Nuclear War is the book’s account of a new destructive power becoming an immediate test of presidential judgment. For Harry S. Truman, the danger was not confined to the bomb’s use against Japan: it reached from the secrecy and urgency of its development to the choices made in Korea and the prospect of an even more powerful weapon. The central tension is between ending wars before more people die and preventing the means of doing so from making a far greater catastrophe possible.

From secret project to presidential responsibility

The scale of the new weapon first reached Truman through fragments rather than a full account. Staff investigators found unexplained expenditures for the Manhattan Project, larger even than those associated with the Canol Project. On June 17, 1943, Truman telephoned Secretary of War Stimson. When Stimson explained that the development was highly secret and that he personally knew about it, Truman accepted his assurance of a specific, unique purpose and did not press him for details. By July, however, Truman knew the project’s essential nature. When Lewis Schwellenbach raised concerns about vast land condemnations for the DuPont Company near Hanford, Truman wrote to reassure him; the threatened secrecy reached across nearly half a million acres.

A later briefing made the implications stark. Alone with Truman in his office, Stimson handed him a several-page memorandum. Its opening warned that within four months the United States would probably have completed “the most terrible weapon ever known in human history,” capable of destroying a whole city with one bomb. The United States and Great Britain had shared in its development, but only the United States could then produce it. Stimson also warned that this advantage could not last and that the Soviet Union might be able to enter production within a few years. The weapon therefore posed a problem beyond the war then being fought: a temporary monopoly was already shadowed by the prospect of other powers acquiring the same destructive capacity.

The narrative also places atomic responsibility within a broader question of who could be trusted to direct national power. The Truman Committee had criticized failures in wartime production management and opposed the divided leadership of the Office of Production Management. Truman told the Senate that if Sidney Hillman could not protect the country’s interests, he should be replaced. The committee also objected to more than 250 dollar-a-year officials, warning that executives who retained corporate ties could serve divided loyalties. These findings were not a direct account of atomic policy, but they show Truman’s insistence that public authority and accountability mattered when private and national interests met.

The choice to use the bomb

The decision emerged amid the continuing destruction of war and uncertainty about how Japan could be brought to surrender. Stimson worried that the United States might be “outdoing Hitler in atrocities,” but also feared that conventional bombing might leave no suitable target on which the atomic bomb could demonstrate its power. Truman laughed at the oddity of this concern, then said he understood. For Stimson and General Marshall, the question was not whether to use the weapon but how to end the slaughter as quickly as possible. Stimson’s earlier instruction to General Groves had been to produce it at the earliest possible date to bring the war to a conclusion.

A harmless technical demonstration was considered and rejected by the committee and its scientific panel. Marshall had initially favored a military target, with manufacturing centers considered afterward and civilians warned to leave. But the scientists could not propose a demonstration likely to create the needed shock. With probably only one bomb ready and uncertainty about whether it would work, a failed demonstration risked strengthening Japan’s resolve rather than prompting surrender. The panel’s members were divided about the first use of the weapon; it found no acceptable alternative to direct military use capable of ending the war.

The competing plans were not always considered together. In his diary, Truman described his hardest decision to date as whether to invade Japan proper or use bombing and blockade. At a White House meeting on June 18, 1945, the invasion plans were discussed without mentioning the Manhattan Project; Stimson’s assistant John J. McCloy noticed that the discussion proceeded as though the bomb did not exist. General Marshall presented a two-phase invasion beginning with Kyushu, 350 miles from Okinawa, and estimated roughly 31,000 losses in its first 30 days. Later, at Potsdam, Truman recalled Marshall estimating that an invasion of the Tokyo plain and other parts of Japan would cost at least a quarter of a million American casualties. The book cautions that there may never have been one clear moment when Truman made up his mind. It emphasizes instead the momentum of the project, the desire to secure surrender, and the human cost of continued fighting.

Truman’s position was not simply that any means were justified. In an August 9 letter, he acknowledged Japan’s cruelty in warfare but rejected the idea that the United States should imitate it. He regretted the necessity of wiping out whole populations because of their leaders’ stubbornness and said he would not do so unless it was absolutely necessary. He hoped Japan would surrender after the Soviet Union entered the war and described his objective as saving American lives while retaining human feeling for Japanese women and children. That evening, in a radio address on Potsdam, he urged Japanese civilians to leave industrial cities. The account holds together his support for using the bomb and his stated concern about the people exposed to its effects, rather than reducing the decision to either calculation or compassion alone.

Korea and the boundary of victory

The same danger reappeared in a different form when North Korea attacked South Korea. Returning from Missouri on June 25, 1950, Truman used the flight to think through the implications and radioed Dean Acheson to arrange an emergency meeting at Blair House. He recalled earlier failures by democracies to resist aggression in Manchuria and Ethiopia. If the attack on the Republic of Korea went unanswered, he reasoned, smaller nations would lose confidence in resisting stronger Communist neighbors; the failure to act might help bring about another world war. The surprise of the attack mattered: Korea had been a possible trouble spot, but had not stood at the top of American assessments, and the last American troops had recently withdrawn from South Korea.

As the war continued, Truman drew a boundary between winning militarily and preserving peace. At an Armed Forces Day dinner on May 18, 1952, he reminded listeners that men were still fighting and dying while Americans at home enjoyed dinner and urged an end to domestic bickering. He argued that the Korean casualties had to be understood against the scale of destruction an atomic war could bring. If victory in Korea risked a world war involving atomic bombs, he would not pursue victory at that price. Peace, he insisted, was an alternative to victory, and he stood by a policy of limited war for that purpose. He condemned proposals to spread the conflict, commit all American resources to a wider Asian war, risk losing European allies, and gamble on whether the Soviet Union would intervene as reckless wagers with the country’s future.

A widening nuclear horizon

In retrospect, Truman called the decision to enter Korea the most important of his presidency and Korea a turning point in the Cold War. Earlier failures to meet aggression had not been repeated, he argued, but the war’s horrific potential had also been kept from getting out of hand. The issue, in his account, was world peace in the nuclear age. That judgment connected the choice to resist aggression with the restraint that kept the conflict limited: action and restraint were presented not as opposites, but as parts of a policy meant to prevent another world war.

The danger grew as the United States entered the thermonuclear era. In his 1953 State of the Union message, Truman reported that recent tests at Eniwetok Island had brought atomic-energy development to another stage. The new weapons dwarfed the mushroom clouds of Hiroshima and Nagasaki. The president who had overseen the first use of atomic bombs was leaving office as destructive power expanded again. He described starting an atomic war as totally unthinkable and cast his policy in Korea as an effort to prevent World War III. The concept’s force lies in that widening contrast: the weapon that had seemed to offer a way to end one war had become a standing danger that made the avoidance of another war a governing responsibility.