Could a terrorist organization acquire and use a nuclear weapon? The idea has proliferated in popular culture, and while it is, according to some experts, a plausible threat, the scenario isn’t quite as likely as action movies and the tv show “24” would have you believe. 
At the height of the Cold War in 1985, there were about 65,000 nuclear weapons in existence worldwide. As a result of the Non-Proliferation Treaty, this number has been reduced to about 20,000 heavily guarded and secured weapons. On the other hand, the raw materials needed to build a nuclear weapon, highly-enriched uranium (HEU) and plutonium, can be found at hundreds of sites in several dozen countries.
Grand Theft Nuclear
Nuclear weapons are well-secured and not easy to detonate, with locks and security codes that would have to be bypassed even if someone got their hands on one. They are also large — unlike Hollywood’s depiction of “suitcase nukes” that can fit in a briefcase and be detonated by one person, standard nuclear weapons would need to be transported at least by truck if not air or sea. During the Cold War the U.S. and former Soviet Union both may have manufactured nuclear weapons designed to be carried and used by one or two people, but security experts do not believe there is now any real threat from this sort of bomb. Though they are depicted as portable, and relatively easy to make and transport, any nuclear device that could fit into a suitcase would realistically be too complex and expensive for a terrorist organization to produce and maintain. Additionally, it would be too heavy for one person to transport, and the material required would cause the electronics around it to degrade, rendering it ineffective.
Beg, Borrow, or Steal
A more likely possibility, according to these same experts, is that a terrorist group could acquire raw materials to produce their own nuclear device. It’s unlikely terrorists would have the materials and expertise needed to covertly make their own HEU and plutonium, which leaves the possibility of theft and illegal purchase. Unfortunately HEU and plutonium are not always as secured as one might expect, and there is no global inventory of these materials. Most sites have state-of-the-art security, but some HEU storage facilities, particularly in places such as India, Pakistan, and former Soviet states, don’t have much more than a security guard and a chain-link fence. The WikiLeaks cables revealed one site in Yemen where weapons-grade radioactive material was sitting in a building with a broken security camera and no guard.
The International Atomic Energy Agency has documented 15 confirmed cases of HEU or plutonium theft, in addition to other unconfirmed reports. In most of these cases, thieves were attempting to sell the material to the highest bidder. Al-Qaeda has been actively seeking nuclear material, according to some reports, for nearly 20 years. Fortunately there is no evidence that any terrorist group has yet succeeded in acquiring nuclear weapons or materials.
Building a Better Bomb
If a terrorist group did acquire nuclear material, how likely is it they would succeed in building and using a nuclear weapon? Scientists say once the essential materials have been acquired, a nuclear bomb could be produced by a few individuals with expert knowledge, using commercially available materials. A basic gun-type bomb, which consists of a shell that can be fired from a cannon, requires about 50 kilograms (110 pounds) of HEU. Implosion bombs are more complicated to make, but need less material — about 6 kg of plutonium or 15 kg HEU. These small amounts can produce a bomb with the force of thousands of tons of high explosives.
It turns out that, at least in small amounts, the materials can be fairly easy to smuggle across international borders. In 2010, two Armenians smuggled about 18 grams of weapons-grade uranium into the former Soviet republic of Georgia by stashing it in a cigarette box lined in lead. This was the third time since 2003 that HEU was intercepted after being smuggled into Georgia; there have been 21 thefts or attempted thefts of uranium and plutonium in the region since the fall of the Soviet Union. In each case the material was not missed and the theft was conducted or arranged by an insider source.
Reducing the Risk
The U.S. has made preventing nuclear terrorism a top security priority in the last two years. Cooperative threat reduction programs have drastically improved security in former Soviet countries, and HEU has been removed from many inadequately secured sites in South America and Southeast Asia. Ukraine and Belarus made a deal with the Obama administration to eliminate all of their remaining HEU. Nuclear reactors fueled with HEU are increasingly being converted to run on low-enriched uranium, which cannot be used to build a bomb. Radiation detectors are installed at many vital ports and border crossings, although as the Georgia case shows, these can be foiled with lead.
The Global Initiative to Combat Nuclear Terrorism now has 82 member nations working to improve the world’s ability to prevent, detect, and respond to terrorist nuclear activity. So, while it is plausible that a terrorist organization could acquire, buy, or even build a nuclear weapon, the international community is aware of the threat and is taking major steps to reduce and possibly eliminate the possibility.
