Stephen M. Walt

Why We Don’t Need to Worry About a ‘Nuclear Handoff’

After the 9/11 attacks, the U.S. national security establishment started focusing on the various ways that "international terrorism" might pose a threat to U.S. interests or the United States itself. Unsurprisingly, experts began to dream up all sorts of frightening scenarios and worry about all sorts of far-fetched scenarios. I remember this period well, and ...

After the 9/11 attacks, the U.S. national security establishment started focusing on the various ways that "international terrorism" might pose a threat to U.S. interests or the United States itself. Unsurprisingly, experts began to dream up all sorts of frightening scenarios and worry about all sorts of far-fetched scenarios. I remember this period well, and I recall sitting through seminars and workshops at which lots of very smart and creative people were imagining various nasty things that groups like al Qaeda might try to do. Hijack gas trucks and blow up the Lincoln Tunnel? Take over the Mall of America and create carnage on a big shopping day? Commandeer a supertanker and smash it into the Verrazano-Narrows Bridge? Wait until summer and then set forest fires all over the American West? The list of conceivable dangers was infinitely long, but if you sat in enough of those seminars, you could easily become convinced that it was only a matter of time before somebody did something really nasty to you or your loved ones.

Imagination is one thing, but disciplined risk assessment is another. It’s easy to dream up bad things that could conceivably happen, but intelligent public policy should rest on a more careful and sustained appraisal of how likely those various scary things are. And that’s why I suggest you read Keir Lieber and Daryl Press’s recent article in the journal International Security on "Why States Won’t Give Nuclear Weapons to Terrorists."

The fear that nuclear-armed states would hand weapons to terrorists has been a staple of U.S. threat-mongering ever since 9/11. It was a key part of the justification for invading Iraq in 2003, and it forms part of the constant drumbeat for military action against Iran. But it never made much sense for two reasons. First, a nuclear-armed state has little incentive to give up control over weapons it has labored long and hard to acquire, for what could the state possibly gain from doing so? Second, a state giving nuclear weapons to terrorists could never be sure that those weapons would not be traced back to it and thereby invite devastating retaliation.

Lieber and Press examine the historical record and show that it is almost impossible to conduct a major terrorist operation and not be blamed for it. Here’s the abstract for their article:

Many experts consider nuclear terrorism the single greatest threat to U.S. security. The fear that a state might transfer nuclear materials to terrorists was a core justification for the invasion of Iraq in 2003 and, more recently, for a strike against Iran’s nuclear program. The logical basis for this concern is sound: if a state could orchestrate an anonymous nuclear terror attack, it could destroy an enemy yet avoid retaliation. But how likely is it that the perpetrators of nuclear terrorism could remain anonymous?

Data culled from a decade of terrorist incidents reveal that attribution is very likely after high-casualty terror attacks. Attribution rates are even higher for attacks on the U.S. homeland or the territory of a major U.S. ally — 97 percent for incidents in which ten or more people were killed. Moreover, tracing a terrorist group that used a nuclear weapon to its state sponsor would not be difficult, because few countries sponsor terror; few terror groups have multiple sponsors; and only one country that sponsors terrorism, Pakistan, has nuclear weapons or enough material to manufacture them. If leaders understand these facts, they will be as reluctant to give weapons to terrorists as they are to use them directly; both actions would invite devastating retaliation.

I might add that this is the kind of important, nonpartisan, policy-relevant work that more social scientists ought to be doing. It is also important to disseminate these findings widely, so that 1) U.S. policymakers won’t keep chasing phantom dangers, 2) the leaders of nuclear-armed states understand that their arsenals are good for deterrence and not much else, and 3) said leaders also understand the need to keep whatever weapons they might have under very reliable control.

Stephen M. Walt is the Robert and Renée Belfer professor of international relations at Harvard University.

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