Can Terrorists Get the Bomb?

By Gary Milhollin

Commentary Magazine
February 2002, pp. 45-49.

The story began over a meal in late October. A high British official told a reporter from the London Times that Osama bin Laden had the bomb, or at least that he had gotten bomb components, or nuclear materials, and that the source was Pakistan. At about the same time, Pakistan arrested three of its nuclear scientists for questioning about possible ties to the Taliban, bin Laden's Afghan protectors. Then, in early November, bin Laden himself declared that he had nuclear weapons, which he would use as a "deterrent."

Could it be true? Countries do not arrest their nuclear scientists for nothing. By mid-November, Graham Allison, a professor at Harvard and an assistant secretary of defense in the Clinton administration, was predicting in the Washington Post that "bin Laden's final act could be a nuclear attack on America." A few weeks later, the Post's Bob Woodward reported that al Qaeda might be making a "dirty" bomb-a radiological device to spread contamination over a wide area. According to Woodward, this could be done by wrapping spent reactor fuel rods around high explosives, which would produce a "zone of intense radiation that could extend several city blocks." A larger bomb, he said, "could affect a much larger area."

In Afghanistan itself, American forces have examined dozens of sites where al Qaeda may have worked on nuclear or radiological weapons. Secretary of Defense Donald Rumsfeld cautioned that while it was "unlikely that they have a nuclear weapon," considering "the determination they have, they may very well."

Despite the reports, and despite the attendant warnings, the risk that a terrorist group like al Qaeda could get the bomb (or a "dirty" substitute) is much lower than most people think. That is the good news. There is also bad news: the risk is not zero.

There are essentially two ways for a terrorist group to lay its hands on a nuclear weapon: either build one from scratch or somehow procure an already manufactured one or its key components. Neither of these is likely.

Building a bomb from scratch would confer the most power: a group that could build one bomb could build several, and a nuclear arsenal would put it front and center on the world stage. But of all the possibilities, this is the unlikeliest-"so remote," in the words of a senior nuclear scientist at the Los Alamos National Laboratory, "that it can be essentially ruled out." The chief obstacle lies in producing the nuclear fuel-either bomb-grade uranium or plutonium-that actually explodes in a chain reaction. More than 80 percent of the effort that went into making America's first bombs was devoted to producing this fuel, and it is no easy task.

To make bomb-grade uranium, a terrorist group would need thousands of high-speed gas centrifuges, machined to exact dimensions, arranged in series, and capable of operating under the most demanding conditions. If they wanted to produce the uranium by a diffusion process, they would need an even greater number of other machines, equally difficult to manufacture and operate. If they followed Saddam Hussein's example, they could try building a series of giant electromagnets, capable of bending a stream of electrically charged particles-a no less daunting challenge. For any of these, they would also need a steady supply of natural uranium and a specialized plant to convert it to a gaseous form for processing.

Who would sell these things to would-be nuclear terrorists? The answer is: nobody. The world's nuclear-equipment makers are organized into a cooperative group that exists precisely to stop items like these from getting into unauthorized hands. Nor could a buyer disguise the destination and send materials through obliging places like Dubai (as Iran does with its hot cargoes) or Malta (favored by Libya's smugglers). The equipment is so specialized, and the suppliers so few, that a forest of red flags would go up. And even if the equipment could be bought, it would have to be operated in a place that the United States could not find.

If manufacturing bomb-grade uranium is out of the picture, what about making plutonium, a much smaller quantity of which is required to form a critical mass (less than fourteen pounds was needed to destroy Nagasaki in 1945)? There is, however, an inconvenient fact about plutonium, which is that you need a reactor to make enough of it for a workable bomb. Could terrorists buy one? The Russians are selling a reactor to Iran, but Moscow tends to put terrorist groups in the same category as Chechens. The Chinese are selling reactors to Pakistan, but Beijing, too, is not fond of terrorists. India and Pakistan can both build reactors on their own, but, for now, these countries are lined up with the U.S. Finally, smuggling a reactor would be no easier than buying one. Reactor parts are unique, so manufacturers would not be fooled by phony purchase orders.

Even if terrorists somehow got hold of a reactor, they would need a special, shielded chemical plant to chop up its radioactive fuel, dissolve it in acid, and then extract the plutonium from the acid. No one would sell them a plutonium extraction plant, either.

It is worth remembering that Saddam Hussein tried the reactor road in the 1970's. He bought one from France-Jacques Chirac, in his younger days, was a key facilitator of the deal-hoping it would propel Iraq into the nuclear club. But the reactor's fuel was sabotaged in a French warehouse, the person who was supposed to certify its quality was murdered in a Paris hotel, and when the reactor was finally ready to operate, a squadron of Israeli fighter-bombers blew it apart. A similar fate would undoubtedly await any group that tried to follow Saddam's method today.

If making nuclear-bomb fuel is a no-go, why not just steal it, or buy it on the black market? Consider plutonium. There are hundreds of reactors in the world, and they crank out tons of the stuff every year. Surely a dedicated band of terrorists could get their hands on some.

This too is not so simple. Plutonium is only created inside reactor fuel rods, and the rods, after being irradiated, become so hot that they melt unless kept under water. They are also radioactive, which is why they have to travel submerged from the reactor to storage ponds, with the water acting as both coolant and radiation shield. And in most power reactors, the rods are welded together into long assemblies that can be lifted only by crane.

True, after the rods cool down they can be stored dry, but their radioactivity is still lethal. To prevent spent fuel rods from killing the people who come near them, they are transported in giant radiation-shielding casks that are not supposed to break open even in head-on collisions. The casks are also guarded. If terrorists managed to hijack one from a country that had reactors they would still have to take it to a plant in another country that could extract the plutonium from the rods. They would be hunted at every step of the way.

Instead of fuel rods, they would be better advised to go after pure plutonium, already removed from the reactor fuel and infinitely easier to handle. This kind of plutonium is a threat only if you ingest or inhale it. Human skin blocks its radiation: a terrorist could walk around with a lump of it in his front trouser pocket and still have children. But where to get hold of it? Russia is the best bet: it has tons of plutonium in weapon-ready form, and the Russian nuclear-accounting system is weak. Russia also has underpaid scientists, and there is unquestionably some truth behind all the stories one hears about the smuggling that goes on in that country.

But very little Russian plutonium has been in circulation, with not a single reported case of anything more than gram quantities showing up on the black market. This makes sense. Pure plutonium is used primarily for making nuclear warheads, it is in military hands, and military forces are not exactly keen to see it come back at them in somebody else's bombs.

One source of pure plutonium that is not military is a new kind of reactor fuel called "mixed oxide." It is very different from the present generation of fuel because it contains weapon-ready material. But precisely because it is weapon-ready, it is guarded and accounted for, and a terrorist group would have to win a gun battle to get close to it. Then they would probably need a crane to move it, and would have to elude or fight off their pursuers.

If terrorists did procure some weapon-ready plutonium, would their problems be over? Far from it: plutonium works only in an "implosion"-type bomb, which is about ten times more difficult to build than the simple uranium bomb used at Hiroshima. In such a device, a spherical shock wave "implodes" inward and squeezes a ball of plutonium at the bomb's center so that it explodes in a chain reaction. To accomplish all this, one needs precision machine tools to build the parts, special furnaces to melt and cast the plutonium in a vacuum (liquid plutonium oxidizes rapidly in air), and high-precision switches and capacitors for the firing circuit. Also required are a qualified designer, a number of other specialists, and a testing program. Considering who the participating scientists are likely to be, the chances of getting an implosion bomb to work are rather small.

The alternative to plutonium is bomb-grade uranium-and here things would be easier. This is the fuel used in the Hiroshima bomb. Unlike the implosion bomb dropped on Nagasaki, this one did not have to be tested: the U.S. knew it would work. The South Africans built six uranium bombs without testing; they knew their bombs would work, too. All these devices used a simple "gun" design in which one slug of uranium was shot down a barrel into another.

The problem with buying bomb-grade uranium is that one would need a great deal of it-around 120 pounds for a gun-type bomb-and nothing near that amount has turned up in the black market. In February 2001 an al Qaeda operative named Jamal Ahmed al-Fadl testified in an American court that he had tried to buy some uranium for $1.5 million in 1993. He had been sent to Khartoum, where he saw a cylinder that supposedly contained uranium from South Africa; he did not know whether the deal went through. South Africa went out of the nuclear-weapon business in 1991, and in 1993 it accounted for all of its bomb-grade uranium to the International Atomic Energy Agency. The deal in Khartoum was probably a scam.

What about getting material from Pakistan? Its centrifuges have been turning out bomb-grade uranium since 1986, and by now there is enough for 30 to 50 nuclear weapons. As is well known, at least some of its nuclear scientists have fundamentalist leanings. Could they spirit out enough for a bomb or two?

The chances are virtually nil. Pakistan's nuclear weapons are its proudest achievement. Every gram of bomb-grade uranium has been produced at the expense of the country's suffering population, and every gram is also part of a continuous manufacturing flow. When uranium leaves the centrifuges, it goes to other plants where it is refined and then to still other plants where it is made into bombs. Pakistan produces enough for about three bombs per year, which means that one bomb's worth is the result of several months' output. If any uranium went missing, it would be as if the assembly workers for Ford Explorers suddenly stopped receiving engines. Someone down the production line would be bound to ask questions, and very quickly.

There is also the fact that Pakistan's nuclear program is controlled by the army, still headed by the country's president, Pervez Musharraf. In response to the September 11 terrorist attack on America, Musharraf created a new military command with direct control over the nuclear-weapons program. In the process, he sidelined officers sympathetic to the Taliban. After all these precautions, Musharraf is unlikely to let any bomb fuel slip through his fingers. The only possibility for terrorists to lay their hands on Pakistan's uranium would be if its government fell under the control of sympathizers; given that Pakistan's army is far and away the most effective and stable organization in the country, there is not much chance of that.

Russia, again, is the best bet. It has tons of bomb-grade uranium left over from the cold war and, in addition to bombs, has used this material to fuel nuclear submarines and research reactors. The result has been to spread it across Russia and several other former members of the eastern bloc.

So Russia and its former satellites are a fat target. This past November, citing a database maintained by the International Atomic Energy Agency, the New York Times catalogued a long series of Russian-related smuggling attempts. In 1993, for example, over six pounds of weapon-grade uranium in St. Petersburg was about to go astray before being seized; in 1998, there was a foiled effort to steal more than 40 pounds in the Urals. Russian officials told the Times that they had twice discovered terrorists staking out their nuclear-weapon sites. Finally, there was one loss "of the highest consequence" during the past year, about which details were not forthcoming.

There are thus definite prospects in Russia. If terrorists could strike the mother lode, and get enough uranium for a gun-type bomb, they would be on their way.

But the way would still be long. They would have to design the bomb, develop it, and build it, and that would be far from a trivial undertaking. They would have to have a competent bomb designer, who could be a physicist or engineer but would have to come with practical experience in making such things work. High-accuracy machine tools could be dispensed with-implosion not being required, much simpler technologies could be used for firing projectiles down artillery tubes-although someone would have to handle the uranium-235, refine it to metallic form, cast it, and then machine it. Still, with the help of a capable machinist and a chemical laboratory, none of these obstacles is insurmountable.

The main risk would lie in getting caught. True, a uranium bomb would not produce many of the "signatures" that American intelligence agencies look for-the use of a lot of electricity (a sign of a uranium enrichment plant), the presence of contaminated air or water (a sign of a reactor or plutonium extraction plant), a noisy testing program-but a fair number of people would have to be recruited, and one of them could turn the others in. Purchase of equipment might arouse the suspicions of a seller. Above all, what would be needed is a sanctuary-a place in which to assemble the people and the equipment, and keep them together for a period of time. You cannot transport such an operation from cave to cave.

Finding this location would not be easy. A country that was aware of the terrorists' program could end up getting blamed for a nuclear attack on America, and not too many governments would be ready to sign up for that. Better from the terrorists' viewpoint would be a location where the authorities had no idea what they were doing, but even so the theft of the uranium would probably be discovered soon enough, and it might be only a short matter of time before the whole world showed up on their doorstep. Besides, if they only managed to steal enough for one bomb, they would still lack an arsenal-and a single mistake in design could wreck the whole project.

Is there no way around these manufacturing problems? There is: stealing, or buying, a complete bomb. But this presents problems of its own, which are even greater.

All countries, including Russia and Pakistan, take care to safeguard their warheads, and even rogue states, if they should get the bomb, would be highly likely to do the same. Despite press speculation to the contrary, countries maintain careful inventories and employ security measures specifically designed to prevent theft. Warheads are typically stored in bunkers to which access is tightly restricted. They are also protected by alarms and armed guards. Terrorists would have a hard fight on their hands taking over one of these bunkers, and even if they succeeded, they would have a much harder fight getting away with the contents.

Buying is not a great option, either. Since the 1970's, the Libyan dictator Muammar Qaddafi has tried to buy nuclear weapons from China, India, and Pakistan, reportedly offering billions of dollars. So far, there have been no takers. In 1996, General Alexander Lebed, then vying for the presidency of Russia, claimed that a number of "suitcase" bombs- meant to be carried by foot soldiers on demolition missions-had gone missing, but his claim was promptly denied by both the Russian and U.S. governments and has never gained much credibility. In November 2001, President Vladimir Putin said he could certify that no Russian warheads had fallen into terrorist hands.

What options remain? Stymied in their plan to acquire a real nuclear weapon, could a determined group of terrorists at least confirm Bob Woodward's fears by manufacturing a "dirty" bomb? Such a device would be much easier to build than a warhead. Instead of producing a nuclear explosion, it would only have to disperse radioactive particles.

This is a likelier bet. But there is a different problem with these devices: they do not pack much radioactive punch. A bomb that carried enough radiation to injure many people quickly would be too hot to handle. The shielding would have to be many times heavier than the radioactive element-so massive, in fact, that there would be no practical way to transport or deploy the weapon. That is why the Pentagon does not consider such devices useful on the battlefield.

Nor is it easy to bring a sufficient amount of radioactivity into contact with a bomb's human targets. Lacing a high-explosive charge with nuclear waste from a hospital or laboratory, for example, would kill some people immediately from the explosion, but the only radiological effect would be an increased risk of cancer decades later. Once the area around the blast was decontaminated, it would be safer to walk through it than to be a serious smoker.

To inflict a dangerous dose over a broad area requires spewing around large amounts of nuclear waste. The only place to get such waste would be from a reactor, and the problems with that scenario have already been demonstrated. Even if a group of terrorists could somehow procure radioactive fuel rods or any other form of highly radioactive waste, wrapping the rods around "readily available conventional high explosives," as Woodward suggested in the Post, would kill the person doing the wrapping. So would transporting such a weapon to its destination, unless the rods were heavily shielded during the entire operation (which would bring us back to the implausible scenario with the giant protective casks). The fact is that it would be a near impossibility to create, in Woodward's words, a "zone of intense radiation that could extend several city blocks."

A research reactor would be a better source. Many countries use such small reactors to irradiate material samples, and it might be possible to insert some material into one of these reactors secretly, irradiate it, and then withdraw it and put it in a bomb. The difficulty would then lie in making the bomb effective. Highly radioactive materials have short half-lives; thus, any bomb would have to be used right away, and one would not be able to build up a stockpile. If enough radioactivity were packed into the bomb to injure a substantial number of victims, the too-hot-to-handle problem would arise. If the radioactive charge were diluted, the bomb would lose its effect. Saddam Hussein actually made and tested such a bomb in the 1980's, but when UN inspectors toured the test site in the 1990's they could find no trace of radiation from it.

What about putting plutonium into a city's drinking water, or into the air? That, too, is a possibility-but according to a 1995 study by the Lawrence Livermore National Laboratory, plutonium dumped into a typical city reservoir would almost entirely sink to the bottom. The little that dissolved would be greatly diluted by the volume of the water, and the people drinking it would get a smaller dose than from natural background radiation. As for plutonium in the air, if an entire kilogram of the stuff were exploded in a city the size of Munich, Germany, and if 20 percent of it became airborne in respirable particles-as with anthrax, the particles would have to be the right size to lodge in the lungs-the effect (according to the same study) would be to produce fewer than ten deaths from cancer.

The main effect of any of these attacks would be panic: people would flee the contaminated zone. This might create a huge economic impact-which would be a victory for the terrorists-and it would be almost certain to create an even huger psychological impact. On the other hand, and unlike anthrax, radiation is something that scientists know how to detect, and at levels far below those that are dangerous. Even the panic might fade quickly as people were reassured that the environment was safe. In any case, there is no chance of achieving anything remotely like the effect of a real nuclear weapon, however small.

In sum, the job of making or procuring a nuclear bomb is a great deal harder than we have been led to believe. From a terrorist's point of view, what is clear above all is that, whether the aim is to build a dirty bomb or a clean one, a sanctuary is needed. The task requires laboratories, equipment, and trained personnel, all of which have to be maintained over a longish period of time.

This in turn underlines the cardinal importance of remaining faithful to our determination to pursue terrorists everywhere, and never leave them in peace. Allowing any group of terrorists to set up shop anywhere puts everyone at risk.

The terrorists' only hope is that we tire of the chase. Then, if they could obtain the bomb, they could deliver it, and anywhere on the globe could become ground zero.