This meeting, jointly sponsored by the Center's International Security Studies and Middle East Programs, and the Los Alamos National Laboratory, was another in the ongoing Nonproliferation Forum series.
Levi's study focuses not on the threat of so-called "dirty bombs" (also referred to as radiation dispersal devices, or RDDs), but on the possibility that a terrorist group might acquire or construct a nuclear weapon. The starting point for thinking about how to prevent nuclear terrorism is to think through how a nuclear plot might unfold. "Without a sense of reality to anchor us," he stated, "we tend to conjure fantastic terrorist schemes, obsess over worst-case scenarios, and demand perfect defenses."
After a failed assassination attempt on British Prime Minister Margaret Thatcher in 1984, the IRA issued a statement: "Today we were unlucky, but remember, we only have to be lucky once. You will have to be lucky always." Levi argued that this proposition applies not only to the defenders, but to the terrorist groups as well. A nuclear terrorist plot would unfold in a sequence of stages (from acquisition of fissile material or a weapon to transporting it across boundaries to successfully detonating the device); the perpetrators must succeed at every stage, while the defenders need success at just one stage to disrupt the plot.
Levi's study assesses the technical and operational barriers to nuclear acquisition by terrorists: "We need to look at just not how terrorists might succeed, but how they might fail." The key to an effective defense is to increase the odds of failure at each stage. Even a small percentage increase of failure at each stage can cumulatively reduce the risk of nuclear terrorism substantially.
Levi debunked popular myths about nuclear terrorism. Foremost among them is the widely held view that the "instructions are on the Internet." Observing that "design is not the hard part," he analogized that just because one can acquire automotive manuals does not mean you can successfully build a car in your garage. Levi was also critical of the nearly superhuman skills frequently attributed to terrorists – for example, if they are successful in one area (such as getting the highly-enriched uranium or plutonium for a bomb), the terrorists can then master the formidable scientific and engineering impediments to weapons acquisition.
Levi said that the debate on nuclear terrorism is polarized between "nuclear zealots," who view the chance of a successful attack as a near certainty, and "nuclear atheists," who judge those odds as close to zero. He called for a third school of "pragmatic agnostics," who work toward ensuring that a low probability event remains so through more effective defense measures based on realistic scenarios.