Nuclear Weapons Are the Greatest Threat to Humankind."

No. But you might think so if you listen to world leaders right now. In his first address to the U.N. Security Council, U.S. President Barack Obama warned apocalyptically, "Just one nuclear weapon exploded in a city -- be it New York or Moscow, Tokyo or Beijing, London or Paris -- could kill hundreds of thousands of people. And it would badly destabilize our security, our economies, and our very way of life." Obama has put nuclear disarmament back on the table in a way it hasn't been for decades by vowing to pursue a nuclear-free world, and, with a handful of big treaty negotiations in the works, he seems to think 2010 has become a critical year

But the conversation is based on false assumptions. Nuclear weapons certainly are the most destructive devices ever made, as Obama often reminds us, and everyone from peaceniks to neocons seems to agree. But for more than 60 years now all they've done is gather dust while propagandists and alarmists exaggerate their likelihood of exploding -- it was a certainty one would go off in 10 years, C.P. Snow authoritatively proclaimed in 1960 -- and nuclear metaphysicians spin fancy theories about how they might be deployed and targeted.

Nuclear weapons have had a tremendous influence on the world's agonies and obsessions, inspiring desperate rhetoric, extravagant theorizing, and frenetic diplomatic posturing. However, they have had very limited actual impact, at least since World War II. Even the most ingenious military thinkers have had difficulty coming up with realistic ways nukes could conceivably be applied on the battlefield; moral considerations aside, it is rare to find a target that can't be struck just as well by conventional weapons. Indeed, their chief "use" was to deter the Soviet Union from instituting Hitler-style military aggression, a chimera considering that historical evidence shows the Soviets never had genuine interest in doing anything of the sort. In other words, there was nothing to deter.

Instead, nukes have done nothing in particular, and have done that very well. They have, however, succeeded in being a colossal waste of money -- an authoritative 1998 Brookings Institution study showed the United States had spent $5.5 trillion on nukes since 1940, more than on any program other than Social Security. The expense was even more ludicrous in the cash-starved Soviet Union.

And that does not include the substantial loss entailed in requiring legions of talented nuclear scientists, engineers, and technicians to devote their careers to developing and servicing weapons that have proved to have been significantly unnecessary and essentially irrelevant. In fact, the only useful part of the expenditure has been on devices, protocols, and policies to keep the bombs from going off, expenditures that would, of course, not be necessary if they didn't exist.

"Obama's Plan to Eliminate Nuclear Weapons Is a Good One."

Not necessarily. Obama's plan, unveiled before the world in a speech in Prague last April, represents an ambitious attempt to rid the world of nukes. Under the president's scheme, developing countries would have access to an internationally monitored bank of nuclear fuel but would be barred from producing weapons-grade materials themselves. Existing warheads would be secured, and major powers such as Russia and the United States would pledge to scale back their weapons programs. In September, the U.N. General Assembly passed a resolution in support of Obama's proposal, giving his massive project some institutional backing.

But all of this is scarcely needed. Nuclear weapons are already disappearing, and elaborate international plans like the one Obama is pushing aren't needed to make it happen. During the Cold War, painstakingly negotiated treaties did little to advance the cause of disarmament -- and some efforts, such as the 1972 SALT Agreement, made the situation worse from a military standpoint. With the easing of tensions after the Cold War, a sort of negative arms race has taken place, and the weapons have been going away more or less by themselves as policymakers wake up to the fact that having fewer useless things is cheaper than having more of them. By 2002, the number of deployed warheads in Russian and U.S. arsenals had dropped from 70,000 to around 30,000, and it now stands at less than 10,000. "Real arms control," wistfully reflected former U.S. assistant secretary of state for arms control Avis Bohlen in an essay last May, "became possible only when it was no longer necessary."

Indeed, both sides have long found that arms reductions were made more difficult if they were accomplished through explicit mutual agreements requiring that an exquisitely nuanced arrangement be worked out for every abandoned nut and bolt. In 1991, for example, the Americans announced that they were unilaterally reducing tactical nuclear weapons, and the Soviet Union soon followed, a development hailed by a close observer, Brown University scholar Nina Tannenwald, as "the most radical move to date to reverse the arms race" and a "dramatic move away from 'warfighting' nuclear postures." This "radical" and "dramatic" feat was accomplished entirely without formal agreement. For the most part, the formal arms-control process has been left trying to catch up with reality. When the U.S. Senate in 1992 ratified a nuclear arms reduction treaty, both sides had already moved to reduce their weapons even further than required by that agreement.

France has also unilaterally cut its arsenal very substantially -- though explaining why France needs any nukes is surely a problématique worthy of several impenetrable dissertations. (Perhaps to threaten former colonies that might otherwise abandon French for English?) The British, too, are under domestic political pressure to cut their nuclear arsenal as they wrestle with how many of their aging nuclear subs they need to hang on to (how about: none?), and the Chinese have built far fewer of the weapons than they could have -- they currently stock just 180.

A negative arms race is likely to be as chaotic, halting, ambiguous, self-interested, and potentially reversible as a positive one. However, history suggests that arms reduction will happen best if arms negotiators keep out of the way. Formal disarmament agreements of the kind Obama seeks are likely simply to slow and clutter the process.

But all nukes are not likely to vanish entirely, no matter the method. Humanity invented these weapons, and there will still be nuclear metaphysicians around, spinning dark, improbable, and spooky theoretical scenarios to justify their existence.

"A Nuclear Explosion Would Cripple the U.S. Economy."

Only if Americans let it.Although former CIA chief George Tenet insists in his memoirs that one "mushroom cloud" would "destroy our economy," he never bothers to explain how the instant and tragic destruction of three square miles somewhere in the United States would lead inexorably to national economic annihilation. A nuclear explosion in, say, New York City -- as Obama so darkly invoked -- would obviously be a tremendous calamity that would roil markets and cause great economic hardship, but would it extinguish the rest of the country? Would farmers cease plowing? Would manufacturers close their assembly lines? Would all businesses, governmental structures, and community groups evaporate?

Americans are highly unlikely to react to an atomic explosion, however disastrous, by immolating themselves and their economy. In 1945, Japan weathered not only two nuclear attacks but intense nationwide conventional bombing; the horrific experience did not destroy Japan as a society or even as an economy. Nor has persistent, albeit nonnuclear, terrorism in Israel caused that state to disappear -- or to abandon democracy.

Even the notion that an act of nuclear terrorism would cause the American people to lose confidence in the government is belied by the traumatic experience of Sept. 11, 2001, when expressed confidence in America's leaders paradoxically soared. And it contradicts decades of disaster research that documents how socially responsible behavior increases under such conditions -- seen yet again in the response of those evacuating the World Trade Center on 9/11.

"Terrorists Could Snap Up Russia's Loose Nukes."

That's a myth. It has been soberly, and repeatedly, restated by Harvard University's Graham Allison and others that Osama bin Laden gave a group of Chechens $30 million in cash and two tons of opium in exchange for 20 nuclear warheads. Then there is the "report" about how al Qaeda acquired a Russian-made suitcase nuclear bomb from Central Asian sources that had a serial number of 9999 and could be exploded by mobile phone.

If these attention-grabbing rumors were true, one might think the terrorist group (or its supposed Chechen suppliers) would have tried to set off one of those things by now or that al Qaeda would have left some trace of the weapons behind in Afghanistan after it made its very rushed exit in 2001. Instead, nada. It turns out that getting one's hands on a working nuclear bomb is actually very difficult.

In 1998, a peak year for loose nuke stories, the head of the U.S. Strategic Command made several visits to Russian military bases and pointedly reported, "I want to put to bed this concern that there are loose nukes in Russia. My observations are that the Russians are indeed very serious about security." Physicists Richard Garwin and Georges Charpak have reported, however, that this forceful firsthand testimony failed to persuade the intelligence community "perhaps because it [had] access to varied sources of information." A decade later, with no credible reports of purloined Russian weapons, it rather looks like it was the general, not the spooks, who had it right.

By all reports (including Allison's), Russian nukes have become even more secure in recent years. It is scarcely rocket science to conclude that any nuke stolen in Russia is far more likely to go off in Red Square than in Times Square. The Russians seem to have had no difficulty grasping this fundamental reality.

Setting off a stolen nuke might be nearly impossible anyway, outside of TV's 24 and disaster movies. Finished bombs are routinely outfitted with devices that will trigger a nonnuclear explosion to destroy the bomb if it is tampered with. And, as Stephen Younger, former head of nuclear weapons research and development at Los Alamos National Laboratory, stresses, only a few people in the world know how to cause an unauthorized detonation of a nuclear weapon. Even weapons designers and maintenance personnel do not know the multiple steps necessary. In addition, some countries, including Pakistan, store their weapons disassembled, with the pieces in separate secure vaults.

"Al Qaeda Is Searching for a Nuclear Capability."

Prove it. Al Qaeda may have had some interest in atomic weapons and other weapons of mass destruction (WMD). For instance, a man who defected from al Qaeda after he was caught stealing $110,000 from the organization -- "a lovable rogue," "fixated on money," who "likes to please," as one FBI debriefer described Jamal al-Fadl -- has testified that members tried to purchase uranium in the mid-1990s, though they were scammed and purchased bogus material. There are also reports that bin Laden had "academic" discussions about WMD in 2001 with Pakistani nuclear scientists who did not actually know how to build a bomb.

But the Afghanistan invasion seems to have cut any schemes off at the knees. As analyst Anne Stenersen notes, evidence from an al Qaeda computer left behind in Afghanistan when the group beat a hasty retreat indicates that only some $2,000 to $4,000 was earmarked for WMD research, and that was mainly for very crude work on chemical weapons. For comparison, she points out that the Japanese millennial terrorist group, Aum Shinrikyo, appears to have invested $30 million in its sarin gas manufacturing program. Milton Leitenberg of the Center for International and Security Studies at the University of Maryland-College Park quotes Ayman al-Zawahiri as saying that the project was "wasted time and effort."

Even former International Atomic Energy Agency inspector David Albright, who is more impressed with the evidence found in Afghanistan, concludes that any al Qaeda atomic efforts were "seriously disrupted" -- indeed, "nipped in the bud" -- by the 2001 invasion of Afghanistan and that after the invasion the "chance of al Qaeda detonating a nuclear explosive appears on reflection to be low."

"Fabricating a Bomb Is 'Child's Play.'"

Hardly. An editorialist in Nature, the esteemed scientific journal, did apply that characterization to the manufacture of uranium bombs, as opposed to plutonium bombs, last January, but even that seems an absurd exaggeration. Younger, the former Los Alamos research director, has expressed his amazement at how "self-declared 'nuclear weapons experts,' many of whom have never seen a real nuclear weapon," continue to "hold forth on how easy it is to make a functioning nuclear explosive." Uranium is "exceptionally difficult to machine," he points out, and "plutonium is one of the most complex metals ever discovered, a material whose basic properties are sensitive to exactly how it is processed." Special technology is required, and even the simplest weapons require precise tolerances. Information on the general idea for building a bomb is available online, but none of it, Younger says, is detailed enough to "enable the confident assembly of a real nuclear explosive."

A failure to appreciate the costs and difficulties of a nuclear program has led to massive overestimations of the ability to fabricate nuclear weapons. As the 2005 Silberman-Robb commission, set up to investigate the intelligence failures that led to the Iraq war, pointed out, it is "a fundamental analytical error" to equate "procurement activity with weapons system capability." That is, "simply because a state can buy the parts does not mean it can put them together and make them work."

For example, after three decades of labor and well over $100 million in expenditures, Libya was unable to make any progress whatsoever toward an atomic bomb. Indeed, much of the country's nuclear material, surrendered after it abandoned its program, was still in the original boxes.

"Iranian and North Korean Nukes Are Intolerable."

Not unless we overreact. North Korea has been questing after nuclear capability for decades and has now managed to conduct a couple of nuclear tests that seem to have been mere fizzles. It has also launched a few missiles that have hit their presumed target, the Pacific Ocean, with deadly accuracy. It could do far more damage in the area with its artillery.

If the Iranians do break their solemn pledge not to develop nuclear weapons (perhaps in the event of an Israeli or U.S. airstrike on their facilities), they will surely find, like all other countries in our nuclear era, that the development has been a waste of time (it took Pakistan 28 years) and effort (is Pakistan, with its enduring paranoia about India and a growing jihadi threat, any safer today?).

Moreover, Iran will most likely "use" any nuclear capability in the same way all other nuclear states have: for prestige (or ego-stoking) and deterrence. Indeed, as strategist and Nobel laureate Thomas Schelling suggests, deterrence is about the only value the weapons might have for Iran. Such devices, he points out, "should be too precious to give away or to sell" and "too precious to 'waste' killing people" when they could make other countries "hesitant to consider military action."

If a nuclear Iran brandishes its weapons to intimidate others or get its way, it will likely find that those threatened, rather than capitulating or rushing off to build a compensating arsenal, will ally with others (including conceivably Israel) to stand up to the intimidation. The popular notion that nuclear weapons furnish a country with the ability to "dominate" its area has little or no historical support -- in the main, nuclear threats over the last 60 years have either been ignored or met with countervailing opposition, not with timorous acquiescence. It was conventional military might -- grunts and tanks, not nukes -- that earned the United States and the Soviet Union their respective spheres of influence during the Cold War.

In his 2008 campaign, Obama pointedly pledged that, as president, he would "do everything in my power to prevent Iran from obtaining a nuclear weapon … everything." Let us hope not: The anti-proliferation sanctions imposed on Iraq in the 1990s probably led to more deaths than the bombs dropped on Hiroshima and Nagasaki, and the same can be said for the ongoing war in Iraq, sold as an effort to root out Saddam Hussein's nukes. There is nothing inherently wrong with making nonproliferation a high priority, so long as it is topped with a somewhat higher one: avoiding policies that can lead to the deaths of tens or hundreds of thousands of people under the obsessive sway of worst-case-scenario fantasies.

Obama has achieved much in his first year as president on foreign policy through toning down rhetoric, encouraging openness toward international consultation and cooperation, and helping revise America's image as a threatening and arrogant loose cannon. That's certainly something to build on in year two.

The forging of nuclear arms reduction agreements, particularly with the Russians, could continue the process. Although these are mostly feel-good efforts that might actually hamper the natural pace of nuclear-arms reductions, there is something to be said for feeling good. Reducing weapons that have little or no value may not be terribly substantive, but it is one of those nice gestures that can have positive atmospheric consequences -- and one that can appear to justify certain Nobel awards.

The confrontations with Iran and North Korea over their prospective or actual nukes are more problematic. Obama and Secretary of State Hillary Clinton have already contributed big time to the hysteria that has become common coin within the foreign-policy establishment on this issue. It is fine to apply diplomacy and bribery in an effort to dissuade those countries from pursuing nuclear weapons programs: We'd be doing them a favor, in fact. But, though it may be heresy to say so, the world can live with a nuclear Iran or North Korea, as it has lived now for 45 years with a nuclear China, a country once viewed as the ultimate rogue. If push eventually comes to shove in these areas, the solution will be a familiar one: to establish orderly deterrent and containment strategies and avoid the temptation to lash out mindlessly at phantom threats.

**John Mueller is professor of political science at Ohio State University and author of Atomic Obsession: Nuclear Alarmism from Hiroshima to al Qaeda.