Nuclear terrorism

Nuclear terrorism is the threat of catastrophic violence made possible by nuclear weapons: not only the destruction of a city by a state in war, but the possibility that a small group could bring a bomb into one without warning. In the book, J. Robert Oppenheimer’s blunt warning about that vulnerability stands beside his broader argument that nuclear danger cannot be managed by accumulating weapons or keeping their workings secret. The danger he described reaches from a hidden bomb in a suitcase to policies capable of annihilating cities—and makes international control, ultimately the elimination of nuclear weapons, the necessary response.

The Vulnerability of the City

In a closed Senate hearing in 1946, Oppenheimer was asked whether three or four men could smuggle parts of a bomb into New York and destroy the city. He answered, “Of course it could be done, and people could destroy New York.” When a senator asked what instrument could detect a bomb hidden somewhere in a city, Oppenheimer replied, “A screwdriver [to open each and every crate or suitcase].” The exchange reduces the problem to its unnerving practical scale: detection would mean searching every container, while a small number of people could pose a threat to an entire city. The book draws the conclusion directly: the only defense against nuclear terrorism was the elimination of nuclear weapons.

That warning makes the bomb not simply a weapon of military advantage but a source of vulnerability. In the author’s account, at the dawn of the nuclear age Oppenheimer understood that the weapon was one of indiscriminate terror and that possessing it had made the United States more exposed to wanton attack. The screwdriver answer is sardonic, but its implication is grave: there is no reliable way to secure an open city against a weapon that can be concealed in ordinary cargo.

From City Destruction to Genocide

The threat of nuclear terror also appears in the scale of the weapons contemplated by policymakers. In 1949, Oppenheimer and the majority of the General Advisory Committee opposed producing a thermonuclear “Super.” Against the Hiroshima bomb’s yield of 15,000 tons of TNT, a feasible Super might release the force of 100 million tons and destroy 150 to 1,000 square miles or more. The committee feared that no legitimate military target could justify a weapon of that size: its report warned that “a super bomb might become a weapon of genocide.” Even its existence, they argued, could make other nations conclude that the United States was willing to contemplate Armageddon, weakening rather than strengthening American security.

The committee also challenged the assumption that matching an adversary’s most powerful weapon would deter its use. If the Soviet Union developed a Super first, it would have to test it, and a test would be detected; meanwhile, the United States’ existing atomic arsenal could provide comparably effective retaliation. The report therefore favored producing fissile material for smaller tactical weapons rather than pursuing a crash program for the Super. This was an attempt to define nuclear sufficiency around specific military purposes instead of an escalating accumulation of weapons. But the proposed alternative carried its own danger: tactical weapons might bring nuclear arms into actual battlefield use, potentially triggering an exchange that grew far beyond the battlefield.

Oppenheimer’s alarm was sharpened by military plans that treated cities as targets on a vast scale. In 1951, he saw an Air Force strategic war plan calling for the obliteration of Soviet cities and described it as criminal genocide. The policy he criticized was not an isolated possibility: the Strategic Air Command’s plan envisioned a massive, initial, unremitting strategic assault. His opposition to indiscriminate destruction thus encompassed both the covert arrival of a bomb in a city and the deliberate destruction of cities through state-directed war.

Secrecy, Retaliation, and Escalation

For Oppenheimer, public ignorance compounded nuclear danger. In discussing the growing American stockpile, he said that the country planned to use its weapons in a massive first assault, while Europeans did not know what the weapons were, how many there would be, how they would be used, or what they would do. He argued that important facts known only to a few people amid secrecy and fear left the public exposed to rumor and confusion. Secrecy could conceal the scale and assumptions of policy, but it could not remove the capacity for attack or prevent the consequences of a mistaken strategic calculation.

The proposed reliance on tactical weapons illustrates the tension between deterrence and escalation. Oppenheimer presented them as support for combat forces rather than weapons of total war, and as an alternative to city-destroying thermonuclear arms. Yet the book notes that battlefield use could operate as a nuclear trip-wire, setting off an exchange of ever-larger weapons. An approach intended to make nuclear strategy more limited could therefore make the first use of nuclear weapons more likely. The distinction between a weapon meant for a battlefield and one meant to terrorize a population did not guarantee that the conflict would remain limited.

International Control and the Warning’s Afterlife

Oppenheimer sought to contain the danger through international control of atomic energy. The Acheson-Lilienthal Report, though named for its sponsors, was conceived and largely written by Oppenheimer; the book describes it as a singular model of rationality in the nuclear age. Cold War politics doomed the plan. The United States and a growing list of other nations embraced nuclear weapons for the next half century, leaving the threat that international control was meant to address unresolved.

The book connects Oppenheimer’s early warning to the post-9/11 era, observing that the danger of nuclear war and nuclear terrorism may be more imminent in the twenty-first century than ever before. It also presents a bitter reversal in his public life: Oppenheimer tried to make the country confront the danger of the weapon he had helped bring into existence, but his warnings were ignored and he was ultimately silenced. After the Atomic Energy Commission hearing board denied his security clearance, dissenting board member Ward Evans called the decision “a black mark on the escutcheon of our country.” The punishment of a prominent critic did not settle the problem he had raised. It left the underlying contradiction intact: weapons defended as instruments of security could make cities vulnerable to terror and nations vulnerable to annihilation.