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Nuclear Terrorism: The Ultimate Preventable Catastrophe

| Aug. 09, 2004

Nuclear Terrorism

In NUCLEAR TERRORISM: The Ultimate Preventable Catastrophe, Graham Allison, founding dean of Harvard’s modern John F. Kennedy School of Government, a former top Pentagon official, and one of America’s leading scholars of nuclear strategy and national security, gives us an urgent call to action. He makes the case that nuclear terrorism is inevitable—if we continue on our present course—and he sets out an ambitious but achievable plan for preventing a catastrophic attack before it’s too late.

Given the number of capable groups with serious intent, the increasing accessibility of weapons or nuclear materials from which elementary weapons could be constructed, and the countless ways by which terrorists could smuggle a weapon across America’s borders, Allison argues that if the U.S. and other governments keep doing what we are doing now, a nuclear terrorist attack is inevitable. Yet Allison is no pessimist. He contends that the big and underreported news is that nuclear terrorism is preventable. “As a simple matter of physics, without fissile material, there can be no nuclear explosion. There is a vast – but not unlimited – amount of it in the world, and it is within our power to keep it secure,” Allison writes. “No fissile material, no nuclear explosion, no nuclear terrorism. It is that simple.” The centerpiece of a strategy to prevent nuclear terrorism must be to deny terrorists access to nuclear weapons and materials. To do this, we must shape a new international security order according to a doctrine of the Three No’s: No loose nukes, No new nascent nukes, and No new nuclear states.

In this timely book, Allison provides in plain and accessible terms the “who, what, where, when and how” of nuclear terrorism – and explains how we can act now to prevent it.


“Graham Allison has written at once a gripping page-turner and a sober how-to manual on preventing nuclear catastrophe. Allison shows how the Bush Administration, despite its repeated warnings of ‘mushroom clouds’ on American soil, has not done what it can to stem proliferation, stave off dirty bomb attacks, or prevent the advent of new nuclear states. Drawing upon his experience in government, Allison offers grim forecasts and recommends workable measures -- measures that could hardly be more timely, or more necessary.”
- Samantha Power, Pulitzer Prize-winning author of “A Problem from Hell”: America and the Age of Genocide.

“Graham Allison’s NUCLEAR TERRORISM is absolutely first-rate. Our survival as a civilization may well depend more than anything else on our heeding the recommendations of this chilling and superbly-crafted book.”
- R. James Woolsey, Former Director of Central Intelligence

“Graham Allison has produced a book that it is truly alarming about the danger of nuclear terror - yet optimistic about our prospects if we do all that we could and should. One only hopes it is read and heeded.”
- Richard Haass, President, Council on Foreign Relations

Frequently Asked Questions about Nuclear Terrorism

  • What is fission?

    Fission is the process that occurs when an atom's nucleus splits, releasing a massive amount of energy.

  • What is fissile material?

    Fissile material is matter that can sustain a fission chain reaction. The two fissile materials used in nuclear weapons are uranium-235 and plutonium-239.

  • Why is fissile material used in nuclear weapons?

    Fissile material is the essential ingredient required to produce the self-sustaining chain reaction that causes a nuclear explosion.

  • What is weapons-grade fissile material?

    "Weapons-grade" refers to purified fissile material that is most suitable for use in a nuclear weapon. A concentration of more than 90 percent is optimal for both uranium-235 and plutonium-239. Nuclear material with much lower concentrations can be used in nuclear weapons, however -- and is sometimes referred to as "weapons-usable." At uranium concentrations less than 20 percent, producing an explosive chain reaction is almost impossible.

  • How much fissile material is needed to make a nuclear weapon?

    As little as 35 pounds of uranium-235 or nine pounds of plutonium-239 is required to make a working nuclear bomb.

  • Is it easier to use uranium or plutonium as the fissile material for a nuclear weapon?

    Uranium-based bombs are easier to make and much less radioactive (and therefore safer to handle) than plutonium bombs. However, four times more uranium than plutonium is needed for a working weapon.

  • Why is producing fissile material the highest hurdle in making a nuclear weapon?

    Making fissile material is expensive and time-consuming, requiring roughly one billion dollars and a decade of intensive effort.

  • How many states have weapons-grade fissile material?

    There are about 40 states with approximately 2,070 tons of weapons-usable fissile material, enough to make more than 130,000 nuclear weapons. (For more information, see Matthew Bunn and Anthony Wier, Controlling Nuclear Warheads and Materials,

  • Is weapons-grade fissile material still being produced today?

    Yes. India and Pakistan openly produce such material for weapons, as does North Korea. Russia continues to produce 1.2 tons of weapons-grade plutonium each year, because the reactors that produce it provide essential heat and power for nearby communities. Israel refuses oversight of its nuclear activities, and is probably still producing plutonium. Iran is actively working to produce it. The U.S. stopped producing fissile material for nuclear weapons in 1992. In addition, facilities in several countries separate tens of tons of weapons-usable plutonium from civilian reactor fuel every year, and this plutonium is piling up in storage -- to the point that it will soon exceed all the world's stockpiles of weapons plutonium combined.

  • Have terrorists acquired fissile material?

    No, not to the best of anyone's knowledge, although terrorists are trying. For example, according to the Justice Department, "from at least as early as 1992, Osama bin Laden . . . and others known and unknown made efforts to obtain the components of nuclear weapons." (For more information, see Matthew Bunn and Anthony Wier, "The Demand for Black Market Fissile Material,"

  • If a president judged it as important as the war on terrorism, how long would it take to lock down the world's supply of fissile material?

    It would take several years to secure the world's supply of fissile material if it was made as high a priority as the war on terrorism. (For more information, Matthew Bunn and Anthony Wier, Controlling Nuclear Warheads and Materials,

  • If a president judged it as important as the war on terrorism, how much would it cost to secure the world's supply of fissile material?

    The total cost would probably be between $30 billion and $50 billion. (For more information, see Howard Baker and Lloyd Cutler, "A Report Card on the Department of Energy's Nonproliferation Programs with Russia,"

  • How long would it take to build a nuclear weapon?

    A decade, even if the necessary technology, funding, equipment and scientific expertise were available, due to the difficulties of producing fissile material. If a group started with fissile material obtained elsewhere, it could make an elementary nuclear weapon in less than one year.

  • Does having a nuclear reactor help in building a nuclear weapon?

    Yes. Several states have used civilian nuclear reactors as a cover to make nuclear weapons. The "spent fuel" waste produced by a civilian reactor contains plutonium that, if separated out, can be used to make a bomb.

  • What is uranium and where is it found?

    Uranium is a radioactive element that can be used in nuclear weapons. It is found in nature -- in hard rock or sandstone -- throughout the world.

  • What is highly-enriched uranium (HEU)?

    HEU is a form of uranium in which the isotope uranium-235 has been increased from its average natural level of 0.7 percent of uranium ore to greater than 20 percent.

  • What is plutonium and where is it found?

    Plutonium is a man-made radioactive element that can be used in nuclear weapons. Only trace amounts of plutonium are found in nature. Almost all existing plutonium is a by-product of nuclear reactors.

  • Are there sizeable supplies of uranium and plutonium?

    Yes. There are huge resources of uranium throughout the world. The human race has produced more than two thousand tons of highly enriched uranium and plutonium.

  • How is weapons-grade uranium-235 extracted out of uranium ore?

    Uranium-235 is slightly lighter in mass than the remaining uranium ore. Separation techniques capitalize on this difference. For example, one method -- gas centrifuge enrichment -- spins gaseous uranium hexafluoride in cylinders, so the lighter uranium-235 moves toward the inner wall, where is it collected. (For more information, see the Wisconsin Project "Bomb Facts: How Nuclear Weapons are Made,"

  • How is plutonium-239 extracted, i.e., what is plutonium reprocessing?

    Plutonium-239 is chemically separated from spent reactor fuel by removing spent fuel rods from a nuclear reactor, chopping them up, and then dissolving them in nitric acid. The resulting liquid is further separated into plutonium, uranium, and radioactive waste. (For more information, see Federation of American Scientists, "Plutonium Production,"

  • How many states have sought nuclear weapons?

    Approximately twenty eight: Britain, China, France, India, Israel, Pakistan, Russia, the United States, and North Korea, as well as Australia, Argentina, Belarus, Brazil, Canada, Egypt, Germany, Iraq, Italy, Japan, Kazakhstan, Libya, Romania, South Africa, South Korea, Sweden, Taiwan, Ukraine, and Yugoslavia.

  • How many states have nuclear weapons?

    Eight: Britain, China, France, India, Israel, Pakistan, Russia, and the United States. North Korea may have two (or as many as eight) nuclear weapons.

  • How many states had nuclear weapons and then relinquished them?

    Four: South Africa had six nuclear weapons by the 1980s and then, just prior to the transfer of power to the post-apartheid government, dismantled them. Ukraine, Kazakhstan, and Belarus together had more than 4,000 nuclear weapons on their territories when the Soviet Union dissolved, and they each agreed in 1994 to return them to Russia.

  • How many nuclear weapons are there in the world?

    The Natural Resources Defense Council estimates that as of 2002, there were around 22,000 nuclear weapons in the world. (For more information, see NRDC, "Table of Global Nuclear Weapons Stockpiles, 1945-2002,"

  • What are the largest and smallest nuclear bombs ever produced?

    The Soviets produced the largest-ever nuclear bomb, "Tsar Bomba," with an estimated yield of 100 megatons -- or 6,500 times the yield of the bombs dropped on Hiroshima and Nagasaki. The U.S. produced the smallest confirmed nuclear weapon, the "Davy Crockett," with a yield of 0.1 kilotons and weighing only 51 pounds.

  • Why do states develop nuclear weapons?

    Nuclear weapons have been developed for a combination of reasons: security, prestige, and domestic bureaucratic politics.

  • If all the resources needed to design a working nuclear bomb are readily available, isn't nuclear proliferation inevitable?

    No. President Kennedy predicted that by 1970 there would be 15 to 20 nuclear weapons states. Although there are over 40 states capable of making a bomb, as of today, only eight have nuclear weapons. The record shows that non-proliferation works when it is given serious attention and resources.

  • What prevents states from seeking nuclear weapons?

    States forgo nuclear weapons for a number of reasons: inadequate national resources, technological constraints, the international nuclear taboo, international treaties, domestic politics, international inducements, security assurances, aid, threats of sanctions and coercion, and the limited strategic utility of nuclear weapons.

  • Is the United States testing or producing additional nuclear weapons?

    No. However, sub-critical testing -- using less fissile material than the critical mass needed for a self-sustaining nuclear fission reaction -- has been performed. And the Bush administration has persuaded Congress to fund new nuclear weapons research.

  • How do states secure their nuclear weapons?

    Optimally, states use a combination of barriers, guards, surveillance cameras, motion sensors, background checks on personnel, and locks built into the actual nuclear weapons. The United States and most nuclear powers employ all these protections. Unfortunately, due to Russia's enormous nuclear stockpile and lack of funds, its nuclear facilities have been left inadequately protected. (For more information, see Matthew Bunn and Anthony Wier, Controlling Nuclear Warheads and Materials,

  • Has the United States ever accidentally lost a nuclear weapon?

    Yes. Experts estimate that at least 11 have been lost. For example, in 1958 a damaged U.S. bomber was ordered to drop a nuclear weapon into the Atlantic before landing. It was never recovered and rests somewhere off the coast of Savannah, Georgia. (For more information, see the Center for Defense Information,

  • Has Russia ever accidentally lost a nuclear weapon?

    Russia denies that any of its nuclear weapons have gone missing although it admits some fissile material has been lost or stolen. Moscow's assurance that "all nuclear weapons are in place" is wishful thinking since at least four nuclear submarines with nuclear warheads sank and were never recovered by the Soviet Union.

  • Have terrorists ever stolen or built a nuclear weapon?

    No, but they are trying to. In 1998, Osama bin Laden issued a statement titled The Nuclear Bomb of Islam, declaring, "It is the duty of Muslims to prepare as much force as possible to terrorize the enemies of God."

  • Has any state ever sold a nuclear weapon to a terrorist?

    No. Although the potential for such a sale exists, there is no documented case of a state selling a nuclear weapon to a terrorist.

  • Could terrorists acquire HEU or plutonium?

    Yes. There have been dozens of documented thefts and sales of fissile material to potential terrorists who were subsequently captured. Russia's substantial amounts of poorly secured HEU and plutonium remain a prime target for theft. (For a regularly updated list of security incidents, see Matthew Bunn and Anthony Wier, Controlling Nuclear Warheads and Materials: "Anecdotes of Insecurity",

  • Could a nuclear power reactor be targeted by terrorists to cause a nuclear explosion?

    There is no possibility of a nuclear explosion at a civilian reactor. However, a terrorist attack on a nuclear power plant could cause a massive release of radiation.

  • Could terrorists deliver a nuclear weapon, or the fissile material required to build one, into the United States undetected?

    Yes. HEU and plutonium are easy to conceal and give off faint radiation signals, and thus could be smuggled into the United States almost as easily as illegal drugs.

  • How are nuclear weapons different from other weapons of mass destruction?

    Nuclear weapons cause immediate, irreversible, widespread destruction. Chemical and biological weapons produce slower-paced, less pervasive effects that can be contained or counteracted.

  • How would a nuclear explosion affect the surrounding area?

    There are three major effects of a nuclear explosion: searing heat, overpressure from the blast, and radiation. The intensity of the effects depends on the yield of the weapon and the distance from the blast (For more information, see the Federation of American Scientists, "Nuclear Weapon Effects,"

  • What is a dirty bomb?

    A dirty bomb uses conventional explosives such as dynamite to spread radioactive material. It is also known as a radiological dispersal device.

  • What is radioactivity?

    Radioactivity is the process by which unstable elements become more stable by emitting particles and energy. This process is measured in "half-lives," the time it takes half of a radioactive material to decay into a more stable element. The half-life of plutonium-239 is 24,000 years; that of uranium-235 is 704 million years.

  • What is radiation?

    Radiation consists of the particles and energy released into its surrounding environment by a decaying unstable element. Sources of radiation include the sun, microwaves, x-ray machines and fissile material.

  • What is radiation sickness?

    Radiation sickness occurs when a person is exposed to large amounts of radiation, usually within a short period of time. Such exposure can cause: nausea, vomiting, weakness, hair loss, hemorrhaging, and death.

  • Is a dirty bomb a weapon of mass destruction?

    No. Instead, it is sometimes called a "weapon of mass disruption" because of the panic it would cause, as well as the costs of decontamination.

  • Is a dirty bomb a nuclear weapon?

    No. A dirty bomb does not result in a nuclear explosion. It only spreads radioactive material.

  • What radioactive materials could be used to make a dirty bomb?

    Any type of radioactive material could be used to make a dirty bomb. Potential sources including americium, cesium and strontium are found in hospitals, at industrial and construction sites, and at food irradiation plants.

  • What is easier to build, a dirty bomb or a nuclear bomb?

    A dirty bomb is easier to make. In its simplest form it is no more then a stick of dynamite and some radioactive material in a shoebox.

  • Has a dirty bomb ever been used?

    The only known dirty bomb-related incident occurred when Chechen rebels planted radioactive cesium packed with dynamite in a Moscow park. Fortunately, the authorities quickly located the material before it was dispersed.

  • What hazards does a dirty bomb pose?

    A dirty bomb's greatest threat is economic cost of decontamination. The blast from the "bomb" part of the device would kill whoever would be killed by the stick of dynamite -- or whatever other explosive material is used. The "radioactive" part of the device would not be likely to cause any immediate deaths but, depending upon exposure and treatment, could increase the likelihood of cancer and other diseases decades later. (For more information, see Peter D. Zimmerman and Cheryl Loeb, "Dirty Bombs: The Threat Revisited,"

For more information, please visit the following online resources:

The single best source is the Nuclear Threat Initiative:

  • Controlling Nuclear Warheads and Materials:
  • NTI also invites interested individuals to get involved in a Safer World Campaign at NTI presents a Safer World agenda and identifies further ways citizens can make a difference.

Additional resources include:

To become more directly involved, activist groups include:

For more information on this publication: Belfer Communications Office
For Academic Citation: Allison, Graham. Nuclear Terrorism: The Ultimate Preventable Catastrophe. New York, NY: Henry Holt & Company, 2004.