However, nuclear proliferation is unlikely to accelerate or prove to be a major danger, and terrorists are likely to continue to find that obtaining and then using nuclear weapons is exceedingly difficult. Moreover, aggressive counterproliferation policies can sometimes generate costs far higher than those likely to be inflicted by the proliferation problem they seek to address. Those policies need careful reconsideration.

Except for their effects on rhetoric, posturing, and military spending, the consequences of nuclear proliferation have been largely benign: countries that have acquired the weapons have “used” them simply to stoke their egos or to seek to deter real or imagined threats. For the most part, nuclear powers have found the weapons to be a notable waste of time, money, effort, and scientific talent. They have generally kept the weapons quietly in storage and haven’t even found much benefit in rattling them from time to time.

Since World War II, there seems never to have been a militarily compelling reason to use nuclear weapons, particularly because it is so difficult to identify suitable targets—or targets that couldn’t be attacked just about as effectively by conventional munitions.

Conceivably, however, conditions exist under which nuclear weapons could serve a deterrent function. There have been suggestions, for example, that nuclear weapons may have kept crises between India and Pakistan from escalating further. And it is also argued that North Korea’s nuclear weapons may have lowered the likelihood that the United States would attack—although that likelihood has never been terribly high even during the long period before North Korea got its nuclear deterrent. Overall, however, there is little reason to suspect that nuclear weapons have been necessary to deter war thus far. This holds even for the Cold War period: neither the United States nor the Soviet Union believed that a repetition of World War II, whether or not embellished by nuclear weapons, was remotely in its interests.

Moreover, nuclear weapons have not proved to be crucial status symbols. How much more status would Japan have if it possessed nuclear weapons? Would anybody pay a great deal more attention to Britain or France if their arsenals held 5,000 nuclear weapons, or much less if they had none? Did China need nuclear weapons to impress the world with its economic growth or its Olympics?

Those considerations help explain why alarmists have been wrong for decades about the pace of nuclear proliferation. Most famously, in the 1960s, President John Kennedy anticipated that in another decade “fifteen or twenty or twenty-five nations may have these weapons.” Yet of the dozens of technologically capable countries that have considered obtaining nuclear arsenals, very few have done so. Insofar as most leaders of most countries (even rogue ones) have considered acquiring the weapons, they have come to appreciate several drawbacks of doing so: nuclear weapons are dangerous, costly, and likely to rile the neighbors. Moreover, as the University of Southern California’s Jacques Hymans has demonstrated, the weapons have also been exceedingly difficult for administratively dysfunctional countries to obtain—it took decades for North Korea and Pakistan to accomplish the task. In consequence, alarmist predictions about proliferation chains, cascades, dominoes, waves, avalanches, epidemics, and points of no return have proved faulty.

Although proliferation has so far had little consequence, that is not because the only countries to get nuclear weapons have had rational leaders. Large, important countries that acquired the bomb were run at the time by unchallenged—and perhaps certifiably deranged—monsters. Consider Joseph Stalin, who in 1949 was planning to change the climate of the Soviet Union by planting a lot of trees, and Mao Zedong, who in 1964 had just carried out a bizarre social experiment that resulted in an artificial famine in which tens of millions of Chinese perished.

Some also fear that a country might use its nuclear weapons to “dominate” its area. That argument was used with dramatic urgency before 2003 when Saddam Hussein supposedly posed great danger, and it has been frequently applied to Iran. Exactly how that domination is to be carried out is never made clear. The notion, apparently, is this: should an atomic rogue state rattle the occasional rocket, other countries in the area, suitably intimidated, would bow to its demands. Actually, states so threatened are far more likely to make common cause with each other and with other concerned countries (including nuclear ones) against the threatening neighbor. That is how countries coalesced into an alliance of convenience to oppose Iraq’s region-threatening invasion of Kuwait in 1990.

Yet another concern has been that the weapons will go off by accident or miscalculation, devastating the planet in the process. But those prognostications have now failed to deliver for over 75 years, and that suggests something more than luck is operating. In fact, as Stephen Younger, former head of nuclear weapons research and development at Los Alamos National Laboratory, notes, “Regardless of what is reported in the news, all nuclear nations take the security of their weapons very seriously.” Moreover, the notion that if one nuclear weapon goes off in one place, the world will necessarily be plunged into thermonuclear cataclysm should remain in the domain of Hollywood scriptwriters.

Anti-proliferation efforts can be counterproductive in their own terms. Thus, “one of the unintended ‘demonstration’ effects of the American anti-proliferation war against Iraq,” notes Mitchell Reiss, an expert on nuclear proliferation, “was that chemical and biological weapons proved insufficient to deter America: only nuclear weapons, it appeared, could do this job.” North Korea has apparently learned this lesson. Insofar as nuclear proliferation is a response to perceived threat, one way to reduce their spread is simple: stop threatening countries that might consider acquiring them.

The impulse to prevent nuclear proliferation by any means available should also be weighed against the potentially very high costs of anti-proliferation economic sanctions and of counterproliferation wars. The war in Iraq and the ISIS insurgency it spawned has resulted in the deaths of hundreds of thousands—greater than the death toll that atomic bombs inflicted at Hiroshima and Nagasaki combined. That war began as a militarized counterproliferation effort, one supposedly required to keep Saddam Hussein’s pathetic regime from developing weapons of mass destruction, including nuclear ones, and to prevent him from transferring some of these weapons to eager and congenial terrorists. Karl Rove, one of President George W. Bush’s top political advisers, reflected in 2008 that, absent this belief, “I suspect that the administration’s course of action would have been to work to find more creative ways to constrain him like in the ’90s.” And anti-proliferation sanctions on Iran and North Korea are currently killing people there. Moreover, North Korea considers the weapons vital to its security—especially to deter any U.S. attempt to overthrow its regime. Thus, it is highly unlikely to budge on the issue at least for the time being, and the nuclear weapons issue stands in the way of making any progress toward normalization of relations in the area.

Alarm about the possibility of nuclear weapons proliferating to terrorists has been raised repeatedly over the decades. In the wake of 9/11, many commentators were predicting that terrorists might well set one off by 2014.

Alarm has tapered some in recent years because it has become increasingly evident that terrorist groups have exhibited only limited desire and even less progress in going atomic. Perhaps, after a brief exploration of the possible routes, they have discovered that the tremendous effort required is scarcely likely to succeed.

One route a would-be atomic terrorist might take would be to receive or buy a bomb from a generous, like-minded nuclear state for delivery abroad. That route, however, is highly improbable. The risk would be too great—even for a country led by extremists—that the source of the weapon would ultimately be discovered. Moreover, the weapon could explode in a manner or on a target the donor would not approve—including, potentially, on the donor itself.

Some observers have worried about “loose nukes,” weapons that can be stolen or bought illicitly. However, Younger’s observation remains relevant: nuclear nations are very serious about the security of their weapons. Moreover, finished bombs are usually outfitted with safety devices that are difficult to defeat.

Most analysts believe that a terrorist group’s most promising route would be to attempt to make a bomb using purloined fissile material—plutonium or highly enriched uranium. However, as the Gilmore Commission—an advisory panel on terrorism and weapons of mass destruction—stressed in 1999, building and deploying a nuclear device presents “Herculean challenges.” As it noted, the process requires a lengthy sequence of steps; if each is not fully met, the result is not simply a less powerful weapon but one that can’t produce any significant nuclear yield at all or can’t be delivered.

Physicists who have studied the issue conclude that fabricating a nuclear weapon “could hardly be accomplished by a subnational group” because of “the difficulty of acquiring the necessary expertise, the technical requirements (which in several fields verge on the unfeasible), the lack of available materials and the lack of experience in working with these.” Others stress the “daunting problems associated with material purity, machining, and a host of other issues” and conclude that the notion that a terrorist group could fabricate an atomic bomb or device “is farfetched at best.”

The notion that terrorists could come up with a nuclear weapon seems remote. As with nuclear proliferation to countries, there may be reason for concern, or at least for interest and watchfulness. But alarm and hysteria are hardly called for.

Allison, Graham T. Nuclear Terrorism: The Ultimate Preventable Catastrophe. New York: Times Books, 2004.

Campbell, Kurt M., Robert J. Einhorn, and Mitchell B. Reiss, eds. The Nuclear Tipping Point: Why States Reconsider Their Nuclear Choices. Washington: Brookings Institution Press, 2004.

Hymans, Jacques E. C. Achieving Nuclear Ambitions: Scientists, Politicians and Proliferation. New York: Cambridge University Press, 2012.

Jenkins, Brian Michael. Will Terrorists Go Nuclear? Amherst, NY: Prometheus Books, 2008.

Levi, Michael A. On Nuclear Terrorism. Cambridge, MA: Harvard University Press, 2007.

Mueller, John. Atomic Obsession: Nuclear Alarmism from Hiroshima to Al-Qaeda. New York: Oxford University Press, 2010.

———. “Nuclear Anti-Proliferation Policy and the Korea Conundrum.” Cato Institute Policy Analysis no. 893, June 22, 2020.

———. “Nuclear Weapons Don’t Matter: But Nuclear Hysteria Does.” Foreign Affairs 97, no. 6 (2018): 10–15.

Younger, Stephen M. Endangered Species: How We Can Avoid Mass Destruction and Build a Lasting Peace. New York: Ecco Press, 2007.