Atomic diplomacy refers to attempts to use the threat of nuclear warfare to achieve diplomatic goals. After the first successful test of the atomic bomb in 1945, U.S. officials immediately considered the potential non-military benefits that could be derived from the American nuclear monopoly. In the years that followed, there were several occasions in which government officials used or considered atomic diplomacy.
During the Second World War, the United States, Britain, Germany and the U.S.S.R. were all engaged in scientific research to develop the atomic bomb. By mid-1945, however, only the United States had succeeded, and it used two atomic weapons on the cities of Hiroshima and Nagasaki to bring a rapid and conclusive end to the war with Japan. U.S. officials did not debate at length whether to use the atomic bomb against Japan, but argued that it was a means to a faster end to the Pacific conflict that would ensure fewer conventional war casualties. They did, however, consider the role that the bomb’s impressive power could play in postwar U.S. relations with the Soviet Union.
While presiding over the U.S. development of nuclear weapons, President Franklin Roosevelt made the decision not to inform the Soviet Union of the technological developments. After Roosevelt’s death, President Harry Truman had to decide whether to continue this policy of guarding nuclear information. Ultimately, Truman mentioned the existence of a particularly destructive bomb to Soviet Premier Joseph Stalin at the Allied meeting at Potsdam, but he did not provide specifics about the weapon or its uses. By mid-1945, it was clear the Soviet Union would enter into the war in the Pacific and thereby be in a position to influence the postwar balance of power in the region. U.S. officials recognized there was little chance of preventing this, although they preferred a U.S.-led occupation of Japan rather than a co-occupation as had been arranged for Germany. Some U.S. policymakers hoped that the U.S. monopoly on nuclear technology and the demonstration of its destructive power in Japan might influence the Soviets to make concessions, either in Asia or in Europe. Truman did not threaten Stalin with the bomb, recognizing instead that its existence alone would limit Soviet options and be considered a threat to Soviet security.
Scholars debate the extent to which Truman’s mention of the bomb at Potsdam and his use of the weapon in Japan represent atomic diplomacy. In 1965, historian Gar Alperovitz published a book which argued that the use of nuclear weapons on the Japanese cities of Hiroshima and Nagasaki was intended to gain a stronger position for postwar diplomatic bargaining with the Soviet Union, as the weapons themselves were not needed to force the Japanese surrender. Other scholars disagree, and suggest that Truman thought the bomb necessary to achieve the unconditional surrender of recalcitrant Japanese military leaders determined to fight to the death. Even if Truman did not intend to use the implied threat of the weapon to gain the upper hand over Stalin, the fact of the U.S. atomic monopoly following the successful atomic test at Alamogordo, New Mexico in July of 1945 seemed to have bolstered his confidence at subsequent meetings, making him more determined to obtain compromises from the Soviet government. Even so, if U.S. officials hoped that the threat of the bomb would soften Soviet resistance to American proposals for free elections in Eastern Europe or reduced Soviet control over the Balkans, they were disappointed, as the security issues raised by the dawn of the atomic age likely made the Soviet Union even more anxious to protect its borders with a controlled buffer zone.
In the years that immediately followed the Second World War, the U.S. confidence in its nuclear monopoly had ramifications for its diplomatic agenda. The fact of the bomb was useful in ensuring that Western Europe would rely on the United States to guarantee its security rather than seeking an outside accommodation with the Soviet Union, because even if the United States did not station large numbers of troops on the continent, it could protect the region by placing it under the American “nuclear umbrella” of areas that the United States professed to be willing to use the bomb to defend. The U.S. insistence on hegemony in the occupation and rehabilitation of Japan stemmed in part from the confidence of being the sole nuclear power and in part from what that nuclear power had gained: Japan’s total surrender to U.S. forces. Though it inspired greater confidence in the immediate postwar years, the U.S. nuclear monopoly was not of long duration; the Soviet Union successfully exploded its first atomic bomb in 1949, the United Kingdom in 1952, France in 1960 and the People’s Republic of China in 1964.
In the first two decades of the Cold War, there were a number of occasions during which a form of atomic diplomacy was employed by either side of the conflict. During the Berlin Blockade of 1948–49, President Truman transferred several B-29 bombers capable of delivering nuclear bombs to the region to signal to the Soviet Union that the United States was both capable of implementing a nuclear attack and willing to execute it if it became necessary. During the Korean War, President Truman once again deployed the B-29s to signal U.S. resolve. In 1953, President Dwight D. Eisenhower considered, but ultimately rejected the idea of using nuclear coercion to further negotiations on the cease fire agreement that ended the war in Korea. In an about face, in 1962, the Soviet deployment of nuclear missiles to Cuba in order to try to force U.S. concessions on Europe became another example of atomic diplomacy.
By the time the United States was attempting to disengage from the war in Vietnam, however, the idea of atomic diplomacy had lost credibility. By the mid-1960s, the United States and the Soviet Union had achieved approximate parity, and their security was based on the principle of mutually assured destruction. Because neither could make the first strike without the threat of a counterstrike, the benefits of using nuclear weapons in a conflict—even in a proxy war—were greatly diminished. So although President Nixon briefly considered using the threat of the bomb to help bring about an end to the war in Vietnam, he realized that that there remained the threat that the Soviet Union would retaliate against the United States on behalf of North Vietnam and that both international and domestic public opinion would never accept the use of the bomb.
In spite of the many threats made over the course of the Cold War, atomic weapons were not used in any conflict after the Second World War. Although the existence of nuclear weapons could continue to act as a deterrent, their diplomatic utility had its limits.