How to Keep the Bomb From Terrorists

In 2007, at the very moment Washington was sitting at the negotiating table with Pyong-Yang to hammer out a nuclear deal, North Korean officials were supplying know-how, equipment and nuclear material to Syria to build a weapons-grade reactor only a few miles from Israel's border. When the news came to light, diplomats and nuclear experts were shocked at Kim Jong Il's duplicity. Israel bombed the Syrian site later that year.

What is Kim Jong Il doing now? The question is foremost on the minds of U.S. national-security officials. Secretary of Defense Robert Gates, when asked recently what keeps him awake at nights, said, "It's the thought of a terrorist ending up with a weapon of mass destruction, especially nuclear." What if Osama bin Laden offered to pay Kim Jong Il $10 million, say, for a nuclear bomb to be exploded in New York City and $20 million for a second bomb destined for Tel Aviv?

U.S. security officials are now convinced that the only effective way to stop Kim Jong Il is to put in place an effective deterrence against such a foolish action, and that the task is urgent. On the bottom-line question of whether a successful nuclear terrorist attack is more or less likely than it was when George W. Bush entered office, just last month the bipartisan Commission on the Prevention of WMD Proliferation and Terrorism offered a unanimous judgment: "Our margin of safety is shrinking, not growing." The key to a new deterrent is coming up with some way of tracing the nuclear material backward from the explosion in New York City to the Pyongan reactors that forged the fissile material, even to the mines in Sunchon-Wolbingson that yielded the original uranium ore.

The idea behind this type of nuclear forensics would be to put doubt in the minds of North Korean officials. The scenario that U.S. intelligence officials imagine is a debate between two North Korean national-security advisers over the merits of a bin Laden offer—let's call them Hawk and Chicken Hawk—in the presence of their leader, Kim Jong Il. Here's how the debate might go:

"We should do the deal," says Hawk. "Under your enlightened leadership, Dear Leader, we have expanded our arsenal to 10 bombs. If we sold two, we'd still have eight bombs left, which is more than enough to deter the United States or South Korea from invading our country to overthrow our regime. And besides, we need the cash."

The prospect makes Chicken Hawk shudder. "If Al Qaeda successfully detonates a nuclear bomb in midtown Manhattan and kills half a million people, don't you think that when the United States discovers the source of the material it will erase North Korea from the map?"

Hawk leans back in his chair and smiles like Dr. Strangelove. "The Americans will not know where Osama got his bomb," he says. "It could just as well have come from Pakistan, where bin Laden is now headquartered."

As things stand now, Hawk might prevail. What U.S. security officials want to do is give Chicken Hawk the upper hand.

Holding nations accountable for their fissile material offers the best prospect available for creating the conditions for a standoff—like the Cold War standoff between the Soviet Union and the United States, in which fear of retaliation prevented each nation from launching its missiles against the other. This "mutually assured destruction" held the peace for decades in large part because missiles have an unambiguous return address. Discovering the origin of a shipping container of black-market plutonium is more challenging, but by no means impossible. Scientists are beginning to figure out just how to do it.

The science of nuclear forensics is key to creating a new deterrence. It entails working backward from a terrorist event—debris from an exploded bomb, or a seizure of fissile material on the black market—to trace the path of the material to its source. The process is analogous to identifying a criminal by fingerprints. Not until the 20th century did detectives learn to capture smudges from a surface, recognize that each is unique to an individual and create a database of fingerprints from known criminals or suspects.

As in normal police work, fingering a nuclear culprit is possible only if one has a database for comparison. Today, the materials terrorists would need for a nuclear device are present in at least 40 countries. Nuclear experts are now at work assembling a vast database of all known sources. In the case of uranium and plutonium, the two elements from which nuclear bombs are made, every step in the nuclear-fuel cycle—mining the uranium ore, converting it into uranium hexafluoride, enriching the uranium and reprocessing the spent fuel—leaves traces that can identify where on the planet the material came from. Ores have different mixtures of elements—uranium and americium or polonium—which emit alpha, beta and gamma radiation at different rates. The mix of plutonium isotopes differs from one type of reactor to another.

After a nuclear bomb detonates, nuclear forensic cops would collect debris samples and send them to a laboratory for radiochemical analysis. By identifying unique attributes of the fissile material, including its impurities and contaminants, one could trace the path back to its origin.

Analysis in the wake of an explosion could also find clues about bomb design. For example, much has been learned about the technology sold by Pakistani nuclear scientist A. Q. Khan and what International Atomic Energy Agency director-general Mohamed ElBaradei called Khan's nuclear "Wal-Mart of private-sector proliferation." Khan had particular ways of arranging the highly enriched uranium core and surrounding explosives in his bombs, which would leave clues even after detonation.

Consider the case of North Korea's reprocessing facility at Yongbyon. Since the country was a member of the nonproliferation treaty subject to inspections by the IAEA, the agency has an extensive library of nuclear materials against which collected samples could be compared. One or more national intelligence communities may also have collected relevant evidence, and it may soon be technically feasible to trace these samples.

In 2002 a study inspired by 9/11 and commissioned by the National Research Council on the role of technology in countering terrorism concluded that "the technology for developing post-explosion nuclear attribution exists but needs to be assembled, an effort that is expected to take several years." By 2008 the American Association for the Advancement of Science was reporting that we are falling short of what we need. In particular, we lack a central global database of unique material signatures that countries can promptly access in the event of a nuclear detonation. According to the AAAS report, the Department of Energy has created a database of uranium compounds, and other government agencies and international partners hold "substantial data, but the consolidation of these data into an accessible nuclear-forensics database has not taken place and the tools to utilize the database have not been developed."

Even if such a database existed, states would not be prepared to take advantage of it after an explosion or other event. As the report asserts, "Neither equipment nor people are at the level needed to provide as prompt and accurate information for decision makers as is possible."

The deterrence that nuclear forensics could provide is not as different from Cold War doctrine as one might think. In the Cuban missile crisis of 1962, the United States discovered the Soviet Union attempting to sneak nuclear-tipped missiles into Cuba. American strategists worried that Nikita Khrushchev might transfer control of the nuclear arsenal in Cuba to a young, hotheaded revolutionary leader named Fidel Castro. After careful deliberation, President John F. Kennedy issued an unambiguous warning to Khrushchev and the Soviet Union: "It shall be the policy of this government to regard any nuclear missile launched from Cuba against any nation in the Western Hemisphere as an attack by the Soviet Union on the United States requiring a full retaliatory response against the Soviet Union." Khrushchev understood this meant full-scale nuclear war.

In the years after the Cuban missile crisis, nuclear strategists wrestled with an array of scenarios in which a Soviet nuclear weapon, or a small number of them, might explode on American soil. The U.S. plan was to retaliate by delivering a nuclear warhead capable of destroying a counterpart Russian city. No one knows whether an American president would in fact have responded to the accidental destruction of Minneapolis by destroying Vladivostok. What was important, however, was that Soviet leaders believed he might and were thus fully motivated to ensure that no accidental launches occur.

In building his case for the U.S. attack on Iraq in 2003, President Bush essentially trashed the traditional doctrine of deterrence. His 2002 West Point address argued that "deterrence—the promise of massive retaliation against nations—means nothing against shadowy terrorist networks with no nation or citizens to defend." But he failed to offer any viable conceptual alternative.

As we face the threat of nuclear terrorism with a weapon that could come not only from North Korea but also from Pakistan or, in time, Iran, the challenge is to revitalize the concept of deterrence. The goal would be twofold: first, to deter leaders of nuclear states from selling weapons to terrorists by holding them accountable for any use of their own weapons; second, to give leaders every incentive to tightly secure their nuclear weapons and materials.

Could personal or national accountability for terrorist use of a nuclear weapon deter leaders from selling weapons to terrorists? To what extent could, or should, accountability apply in cases where proliferation is the result of negligence, not intent? Hard questions, yes, but questions 21st-century strategists must not only ask but also answer.

The capability to identify the source of nuclear material in a credible fashion is not enough to prevent nuclear terrorism. The world needs an accepted principle of nuclear accountability—and it should begin with the United States and Russia, since they still own 95 percent of all nuclear weapons. They should take the lead in establishing a new organization called the Global Alliance Against Nuclear Terrorism. Its goal should be to minimize the risk of such terrorism by taking every action physically, technically and diplomatically possible to prevent nuclear weapons or materials from falling into the hands of terrorists.

Membership in the alliance would require an unambiguous commitment to the principle of assured nuclear security. States would have to guarantee that all nuclear weapons and materials in their territories were secured to a "gold standard"—beyond the reach of terrorists or thieves. And states' means of securing these materials would have to be sufficiently transparent that leaders of other member states could reassure their own citizens that terrorists would never get a nuclear bomb from another alliance member. In addition, member states would be required to deposit samples of nuclear materials in an international library that forensic technicians could use in identifying the source of any weapon or material that found its way into the hands of terrorists.

If nuclear weapons or materials should be stolen, states that had satisfied the requirements for assured nuclear security, met the new standards in securing their materials and made their safeguards sufficiently transparent to the other members would be judged less harshly. A state that was unwilling to participate fully in the alliance would automatically be put on a list of suspect sources of a terrorist nuclear bomb. If a member of the alliance was found to have knowingly allowed nuclear materials to fall into terrorist hands, it would face consequences—anything from financial reparations to military retaliation—worked out in advance.

The grim reality is that President Bush failed to organize and execute a coherent strategy against what he rightly called "the single most serious threat to the national security of the United States." While devoting more than a billion dollars to cargo scanning, the Bush administration invested only tens of millions in nuclear forensics.

President Obama has declared that nuclear terrorism is "a threat that rises above all others in urgency" and has committed his administration to action. Updating 20th-century concepts of nuclear deterrence to meet 21st-century threats should be a high priority for his administration, and there are signs that it is. Before he became vice president, Joe Biden called for "a new type of deterrence" to restrain countries that might contribute to a terrorist attack. Establishing a general principle of nuclear accountability that will apply to Pakistan, Iran or even Russia and the United States is an undertaking for the global alliance discussed above. But this will take months of consultations. The time to deter Kim from the extreme act of selling a nuclear weapon to terrorists is now. The new administration should act immediately to convince him that North Korea will be held fully accountable for every nuclear weapon that comes from North Korea. Ideally, the United States would act in concert with Russia and China in taking a page from Kennedy's playbook during the Cuban missile crisis. A specific policy of nuclear accountability for North Korea would warn Kim directly and unambiguously that the explosion of any nuclear weapon of North Korean origin on the territory of these states or their allies will be met with a full retaliatory response.