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This summer, for the first time, there will be a negotiation under the auspices of the United Nations on the convention banning the production, possession, and use of nuclear weapons. The United States and Russia, as well as other nuclear states, are expected to boycott the talks in the hope that they can delegitimize the effort. Instead, both countries are engaged in major modernization programs. The United States is committed to replacing its entire triad of nuclear-armed missiles, submarines, and bombers at a cost that may exceed a trillion dollars over 30 years. Russia has announced the revival of myriad Soviet-era nuclear weapons programs, including new intermediate-range ballistic and cruise missiles, a new heavy intercontinental-range ballistic missile, nuclear-armed trains, and an underwater drone with a thermonuclear warhead that is designed to detonate in a port in a city like New York.

The U.N.-sponsored nuclear-weapons-ban treaty negotiations—convened under the leadership of Austria, Brazil, Ireland, Mexico, South Africa, and Sweden, and with the support of 120 countries worldwide and a host of disarmament groups—are deeply imperfect, having arisen in response to the hostility of the major nuclear-armed states to the idea of a nuclear weapons convention. Yet they also offer an opportunity, if we take it. Not, perhaps, to eliminate nuclear weapons in a single stroke, but to force a serious discussion about how to base our security on something other than the permanent threat of nuclear holocaust.

Indeed, the election of Donald Trump has triggered a renewed interest in the danger of nuclear war. As commander-in-chief, he has the unfettered authority to order a nuclear strike—contrary to the widespread folk wisdom, no second “vote” is required. During the campaign, this incredible power became shorthand for the awesome responsibility of the office, and the ground on which partisans battled over Trump’s fitness to serve as president. Trump, too, has embraced nuclear weapons as the ultimate trapping of his status, frequently expressing the notion that the U.S. nuclear arsenal must remain, in his phrase, at the “top of the pack.” But what does the rest of the pack look like? Where are we today? And what dangers might we head off?

These important questions go well beyond the politics of the moment, extending to the heart of how we think about security and the future of humankind. The dominant view has long been that nuclear weapons are just the latest in a series of armaments that human beings have created to wage war. Another view, also present from the beginning of the atomic age, is that nuclear weapons are not merely the most recent, but also a first—the first weapon that offers us the ability to destroy ourselves, a shared hazard for which our social institutions for managing large-scale violence are dangerously ill-suited.

These two competing views each saw new development after the dawn of atomic weapons and during the Cold War arms race—the invention of far more destructive thermonuclear weapons, the integration of computerized command-and-control systems, and so on—in radically different terms. Those who favored nuclear primacy saw another step in an endless competition for national superiority. Those who opposed it saw an increasingly elaborate machinery for destruction that was growing too complex for existing human systems to control or even for a single human being to fully comprehend.

So far, we have built our security on nuclear deterrence, calculating that discouraging war among the great powers is worth the long-term risks, and thus we have sought to stay ahead in an ongoing arms race. In this regard, Trump’s comments about the bomb are in keeping with a commonplace view that U.S. nuclear weapons should be “second to none.” At the same time, other voices have cautioned against the emptiness of such rhetoric, reminding us that there is no victory in an arms race or a nuclear war, and that we cannot expect nuclear deterrence to work perfectly forever. Human beings are frail, and our leaders are imperfect. Over time the risks continue to accumulate: the complexity of the enterprise of nuclear deterrence is steadily deepening as rapid technological advancements entangle new states and make possible new weapons with unpredictable consequences.

We are, today, living through a momentous era of technological disruption that has deeply altered our economic and social patterns of life. Imagine explaining to a colleague, even two decades ago, the ubiquitous presence of smartphones, social media, and Uber, plus the prospect of driverless cars. Yet some people, apparently including the president, believe that nuclear deterrence can continue to muddle along as it always has, without succumbing to the forces that have imperiled landline telephones, print newspapers, taxicabs, and human drivers. This seems unlikely. Technology is certain to disrupt nuclear deterrence. The only question is whether that means the end of nuclear weapons or the end of us.

THE BIG TWO: THE UNITED STATES AND RUSSIA

Today, nine countries have nuclear weapons. They are, in the approximate order in which they acquired the bomb, the United States, Russia, Britain, France, China, Israel, India, Pakistan, and North Korea.

Collectively, these countries possess more than 10,000 nuclear weapons, most of them of the thermonuclear variety, many times more destructive than the simple fission bombs that destroyed Hiroshima and Nagasaki. To put this in perspective, the most common nuclear weapon in the U.S. stockpile, the W76, has an explosive force of about 100,000 tons of TNT (100 kilotons)—five times the size of the implosion device dropped on Nagasaki. The largest nuclear weapon ever tested, the Soviet Union’s Tsar Bomba, exploded with a force of 57 million tons of TNT (57 megatons).

Talk of things such as stockpiles, megatonnage, and the throw-weight that missiles can carry are a regular feature of the discussion of nuclear danger. Such grim accounting may seem inadequate and antiseptic, but it represents a feeble human attempt to make some sense out of our nuclear predicament, to impose some order or pattern on this enormous capacity to commit collective suicide. The inadequacy of statistics to convey the full horror of nuclear weapons may actually be an advantage—it creates a kind of psychological distance that allows us to survey this current predicament without falling into hopelessness or despair.

The United States and Russia possess the bulk of the world’s nuclear weapons, the warheads in their respective arsenals numbering in the thousands. Still, these numbers are much reduced from Cold War peaks, in which at different points each country had as many as 30,000 nuclear weapons in a bewildering array of options to arm bombers, missiles, and artillery pieces, and even to serve as landmines.

Under the Obama administration, the United States periodically disclosed the precise number of nuclear weapons in the U.S. stockpile—at the end of fiscal year 2015, that number was 4,571. Higher numbers are sometimes quoted, partly because the official figure does not include many thousands of American nuclear weapons that are nominally retired but that have not yet been dismantled. The Obama White House had hoped Russia would respond with its own accounting, but Moscow has remained silent. Nevertheless, most experts believe that Russia’s overall stockpile is similar in size to that of the United States, numbering several thousand nuclear weapons.

The rough numerical parity hides, however, deep differences in the composition of those stockpiles. Nuclear weapons are categorized as “strategic” or “tactical”—although in practice there is very little difference between the two. For example, the U.S. B61 nuclear bomb has both strategic and tactical modifications that are now being replaced by a single design for all missions, the B61-12. Still, the distinction between strategic and tactical nuclear weapons is codified in arms reduction treaties, and helps explain the vastly dissimilar preparation that the United States and Russia make for nuclear war. Owing to arms limits negotiated in the 2010 New start treaty, the United States and Russia will reduce the number of strategic nuclear weapons to no more than 1,550 deployed warheads—although in practice, treaties use a fair amount of accounting, meaning that the real number of nuclear weapons is higher than the limit. Bombers, for example, count as a single nuclear weapon under the New start treaty, even though the B-52 can carry as many as 20 nuclear-armed cruise missiles.

Both the United States and Russia have thousands more bombs and warheads that are not covered by these treaties, resulting in total nuclear stockpiles that are similar in size only. The United States holds its additional warheads as nondeployed, or spare, warheads for its strategic nuclear forces, placing emphasis on redundancy to ensure against any technical problems that might arise. The United States has only a few hundred “tactical” nuclear weapons. Russia, by contrast, keeps almost no spares (Moscow is far less worried about reliability) and between 3,000 and 5,000 tactical nuclear weapons. These are largely thermonuclear weapons, many with yields that are comparable to so-called strategic weapons.

Even with the great reduction in nuclear weapons since the Cold War, Russia and the United States maintain the same operational patterns for these systems. Both countries keep a significant portion of these forces on day-to-day alert, allowing each side to launch a great number of nuclear weapons in the narrow window of about 30 minutes between the time a launch of enemy missiles is detected by satellites and the time those enemy missiles arrive.

Organizing for this mission—which the United States calls “launch under attack”—leaves almost no time for decision-making. President Trump, for example, would have between two and four minutes to decide that computerized reports of an attack are not a false alarm and to give the order to retaliate. President Vladimir Putin would face the same time constraint. Although discussions of arms control and stability have largely focused on limiting the number of nuclear weapons, the growing fear that one side might “decapitate” the other by killing its leadership in a precision strike or taking down its communications in a cyberattack creates considerable instability.

Achieving even this slender window for decision-making requires an enormously complex computerized system to detect missile launches, convey that information to the president, and then transmit and execute his order. Every minute that is lost to these processes reduces the time in which the president must decide. As a result, the pressure to automate much of the system is strong. This was especially true for the Soviet Union, which developed a semi-automated system called Perimeter that ensured retaliation even if everyone in the Kremlin were killed, earning it the dark nickname “The Dead Hand.”

Computerization speeds communications, but it also introduces the risk of false alarms. There have been well-documented incidents in the U.S. warning system, including one that resulted from the failure of a 46-cent computer chip. Such problems have gotten worse, not better. In recent years, the U.S. Department of Defense has struggled with the growing problem of counterfeit computer chips making their way into sensitive systems. In 2011, for example, the head of the Missile Defense Agency admitted that a counterfeit Chinese computer chip had been installed into the mission computers for Thermal High Altitude Area Defense (thaad) missile defense systems. Counterfeit chips might simply fail, or they might represent a possible infection vector for malware.

Many Americans have become aware of the so-called “Internet of things”—the vast but largely unnoticed number of smart appliances and objects that connect to the Internet. A few years ago, the National Security Agency discovered suspicious electronic emissions coming from a sensitive facility—a significant breach of security. After a long investigation, the culprit turned out to be a soda machine, communicating to its vendor over the Internet that it needed to be restocked. What happens when the Internet of things includes nuclear weapons? An odd question, perhaps, but one that the Air Force Scientific Advisory Board is asking. New nuclear weapons systems “will be much more like all systems today, network connected,” the head of the board told reporters. “They’ll be cyber-enabled”—suggesting that new systems will be as much a part of the Internet of things as thermostats and refrigerators.

THE REST OF THE PACK

The numbers held by the United States and Russia dwarf the arsenals of “second-tier” nuclear powers: Britain, France, and China. These arsenals total a few hundred weapons each. Britain maintains fewer than 200 nuclear weapons for its fleet of four ballistic missile submarines. France has approximately 300 nuclear weapons for both submarines and some aircraft.

Unlike Britain and France, the People’s Republic of China is modestly expanding its nuclear arsenal by deploying new nuclear-armed, long-range missiles and new nuclear-armed submarines. Although the scope of this modernization is unclear, China may move from the smallest of the second-tier states to a category somewhere above Britain and France, but still well below the United States and Russia.

But numbers do not tell the entire story. China’s nuclear forces have always been small, but more important, unlike Russia and the United States, it did not keep its nuclear weapons on alert. China’s nuclear warheads were stored separately from the missiles that would deliver them. As a result, China avoided becoming entangled in the kind of tightly coupled relationship that drove the United States and Soviet Union to develop highly alert nuclear postures that were also susceptible to false alarms.

Now, however, China is introducing new nuclear systems, including mobile missiles that are transported by trucks and carried by submarines, some of which may be kept on alert during peacetime. In the event of a crisis, Chinese officials have talked about placing the other forces on alert to signal their resolve to resist what they would call nuclear blackmail by the United States. This risks creating precisely the sort of trap that has ensnared the United States and Russia. To make matters worse, many of the new weapons in which China is investing can be armed with both conventional warheads and nuclear warheads. The Chinese appear to be placing a dangerously dubious bet that the United States will be able to tell the difference.

For many years, Israel, India, and Pakistan were called “opaque” proliferators—meaning they did not openly acknowledge their nuclear status—although few experts had any doubts about it. Israel maintains this position to the present day, unconvincingly, but both India and Pakistan moved to overt deployment of nuclear weapons following the 1998 nuclear tests conducted by both countries.

The nuclear standoff in South Asia is especially disconcerting because India and Pakistan have moved to replicate the nuclear postures of the United States and Russia in miniature, including tactical nuclear weapons, cruise missiles, submarine-launched ballistic missiles, and missile defenses. An alarming difference is the two countries’ proximity. If the 30 minutes that it would take for an intercontinental ballistic missile to fly from Russia to the United States imposes crushing time pressures, consider that flight times in South Asia will be five to 10 minutes, depending on the missile and the target. India and Pakistan are re-creating a Cold War deterrence framework under much more demanding conditions.

Finally there is North Korea. Despite openly flaunting its nuclear status with five nuclear explosions since 2006, Pyongyang has maintained a curious silence about its growing nuclear capabilities. Yet during the past two years, North Korea openly displayed a model of its “standardized” nuclear warhead for arming its ballistic missiles, conducted a nuclear test of that warhead, and shifted missile testing to the units that would be required to use nuclear weapons in any conflict. These steps are totally consistent with the warnings of North Korean defectors that Pyongyang is now in the process of deploying nuclear weapons to its missile units for use if a conflict were to break out. North Korea’s nuclear strategy, as indicated by official documents, defector reports, and launch exercises, is to use nuclear weapons early in any conflict to destroy U.S. forces at bases and ports in South Korea and Japan to repel an invasion, while holding a small number of nuclear-armed ICBMs in reserve to deter the United States from responding in kind. This spring, the United States conducted large-scale military exercises with South Korea. North Korea responded with its own exercise, launching four missiles into the ocean in a simulated nuclear strike on a U.S. air station supporting the exercise.

NEW PROBLEMS

South Korea’s response to North Korea illustrates a significant complication in how we think about nuclear deterrence. In the past, conventionally armed missiles were too inaccurate to play a strategic role, and missile defenses offered too little chance of protection. But today, South Korea and other countries facing nuclear threats have increasingly invested in ballistic and cruise missiles with conventional warheads, aiming to kill the leaders of their adversaries before an order to use nuclear weapons can be given, and advanced missile defenses to mop up any missiles that might be missed. Not only South Korea, but also India, Taiwan, and a number of Middle Eastern countries have sought to develop advanced conventional missile and missile defense capabilities, dramatically complicating how we think about deterrence. Russian officials, too, frequently complain about the destabilizing effects of such systems. After all, such a strategy places an enormous premium on going first.

Yet this problem pales in comparison to the uncertainty generated by the emerging possibility of disarming cyberattacks that could take down command-and-control nodes. If in the past we counted the number of nuclear weapons on each side to determine a rough balance, how do we assess the possibility that there may be zero-day exploits in the systems used to launch missiles or operate missile defenses? As the term “zero day” suggests, such an attack would be a surprise using a previously unknown vulnerability. In a crisis, leaders contemplating the use of nuclear weapons might not be confident that their command-and-control systems were secure from hacking, since zero-day exploits are by definition unexpected. Fearing a disabling cyberattack on nuclear command-and-control systems, those leaders might feel pressure either to use nuclear weapons early or to delegate launch authority to lower-level commanders.

It is tempting for those states now actively engaged in nuclear-deterrence relationships to look to the past for clues about how to muddle through. But the technological universe of the Cold War might as well be the era of the steamship. The number of states with advanced capabilities, and the challenges those capabilities pose to stability, present a world that looks very little like the simple models based on mutually assured destruction that dominated early discussions of deterrence.

Many experts still believe that technology will provide an escape from nuclear danger. At the beginning of the Cold War, many U.S. political and military leaders sought to preserve the American atomic monopoly. After the Soviets became a nuclear state, these same leaders believed thermonuclear weapons would provide a durable American advantage. A series of new technologies—missiles that could be carried by submarines or land-based vehicles, smaller warheads that could be packed in large numbers on a single missile, improved accuracy, unusual effects such as the so-called “neutron bomb”— all deepened the arms race, rather than providing an escape. Later came the Strategic Defense Initiative (SDI), which by enabling the United States to destroy an incoming Soviet strike in flight, would finally provide the elusive solution to the nuclear nightmare. One after another, though, technological innovations proved fleeting, each offering a smaller and briefer advantage than the last.

Today, missile defenses and advanced conventional strike capabilities seem to offer hope for a technological escape. But even as these systems are growing in capability, the same underlying technologies that make them possible can also support the development of countermeasures to defeat them. The United States is testing a new hypersonic weapons system that can carry conventional payloads across the globe, offering a nonnuclear strike capability. China is testing the same kind of hypersonic system, but to carry its nuclear warheads past American missile defenses. The nuclear knot only tightens the more we grasp at each new technological marvel.

AN ESCAPE?

Any escape from the danger posed by nuclear weapons is going to take political, not technical, innovations—a fact recognized almost immediately by the scientists and engineers who brought the bomb into being. “The unleashed power of the atom has changed everything save our modes of thinking,” Albert Einstein wrote in an appeal to raise money for a public education effort, “and thus we drift toward unparalleled catastrophe.”

Having given humanity the technical capacity to destroy itself, many scientists sought a political solution, trying to bring about changes in human institutions and behaviors that would allow us to adapt to the new, hostile technological environment. In the United States, this view led scientists to undertake public advocacy efforts. Einstein and Leo Szilard, among others, founded the Emergency Committee of Atomic Scientists “to carry to our fellow citizens an understanding of the simple facts of atomic energy and its implications for society.” Other well-known scientists founded groups that evolved into the Federation of American Scientists and that published the Bulletin of the Atomic Scientists.

Despite these efforts, the arms race between the United States and Soviet Union proceeded in earnest, producing decades of constant dread punctuated by deeply terrifying moments of crisis. Throughout that time, many Americans believed escape was just around the corner, with one more technological innovation that would provide superiority. But the Cold War ended through political accommodation, not technical wizardry. Soviet leader Mikhail Gorbachev allowed the Berlin Wall to fall and the Warsaw Pact to disintegrate, then stood by helplessly as the Soviet Union itself succumbed to its own internal failures. Our escape from the arms race was a change in political orientation. Gorbachev called his approach to Soviet domestic and foreign policy “new thinking.”

The arms race ended only because the Soviet Union ceased to be. Fairly quickly, though, a cottage industry arose to argue that the United States had outspent the Soviet Union, that the prospect of SDI had ended the arms race. This myth would prove costly, as afterward the United States allowed Russia’s economy to collapse, fraying the country’s social fabric and creating the conditions for the rise of Vladimir Putin, who promised to end the misery inflicted during Russia’s brief experience with free-market democracy. The United States and Russia failed to alter their security relationship, leaving in place nuclear arsenals that continued to operate in the same fashion as during the Cold War. They likewise failed to create durable European security institutions. Although each side reduced numbers, both countries retained significant quantities of nuclear weapons vastly in excess of any conceivable purpose, embedded in an adversarial relationship in which an expanding NATO and far weaker Russia continued to base their security on the threat of nuclear war. Often, reductions were presented as having been enabled by new technologies—more accurate nuclear weapons or new conventional systems that could replace larger nuclear weapons. Simply put, smaller numbers merely masked a continuing belief that technology might offer more security from a resurgent Moscow than political solutions.

There is, of course, an alternative approach: the elimination of nuclear weapons altogether. The past decade has seen one of the periodic waves of enthusiasm for efforts at nuclear disarmament, beginning with the January 2007 publication of an unusual opinion piece in The Wall Street Journal, signed by former Secretaries of State George Shultz and Henry Kissinger, former Secretary of Defense William Perry, and retired U.S. Senator Sam Nunn. The four men quite deliberately sought to use their reputations and gravitas as distinguished statesmen to create political space within Washington for a renewed discussion of disarmament.

Individuals and organizations embraced disarmament rhetoric for different reasons. Even among the four statesmen, there were apparent differences. For Shultz, the 1986 summit at Reykjavik where Ronald Reagan and Gorbachev nearly agreed to eliminate all nuclear weapons loomed large as a missed opportunity. For others, like Perry, elimination seemed more like an aspirational goal to create the necessary enthusiasm for other steps, such as the ratification of the Comprehensive Test Ban Treaty. As Nunn observed in congressional testimony in 2007, “To me, the goal of a world free of nuclear weapons is like the peak of a very tall mountain. It’s tempting and easy to say: ‘We can’t get there from here.’ Today, we can’t see the top of the mountain, but we can see that we’re headed down instead of up.” Yet others, including nongovernmental organizations like Global Zero, argued for complete disarmament as a near-term goal, proposing a time-bound convention on the elimination of nuclear weapons.

In 2008, Barack Obama, campaigning for the Democratic presidential nomination, saw that political space as an opportunity to distinguish himself from his primary opponent, Hillary Clinton. Obama pledged that, if elected, he would state clearly his desire to “set and seek the goal of a world with no nuclear weapons.” Once in office, however, the Obama administration was forced to be explicit about how its disarmament rhetoric would be reflected in policy. During a speech in Prague in 2009, where the president made good on his pledge to state his support for disarmament, he felt compelled to add that he did not expect this to occur in his lifetime—an implicit rejection of those seeking a nuclear weapons convention. Later, in 2010, then–Undersecretary of State Ellen Tauscher told a summit convened by Global Zero, which was seeking the elimination of nuclear weapons within 20 years, that the president’s commitment to disarmament was aspirational, and that efforts “likely will exceed 20 years and that it might not happen in his lifetime.”

During the 2010 Nuclear Posture Review, a study of U.S. nuclear weapons and strategy, a group of distinguished experts, including Perry, pressed the president to pledge that the “sole purpose” of nuclear weapons was to deter an attack. The proposal was rejected, though with a promise to revisit it as more advanced conventional weapons increasingly replaced nuclear ones. Even President Obama seemed to place his hopes for disarmament in technology rather than political will.

This kind of thinking is not only harmful, but misguided—harmful because it makes the case that disarmament can only occur once we replace nuclear weapons with a fresh set of horrors. Russian experts, in particular, argued that the United States was merely promoting nuclear reductions to emphasize American conventional capabilities. They likewise warned that the very conventional capabilities that would allow the United States to reduce the role of nuclear weapons would force Russia to increase its reliance on the bomb.

The contention that nuclear weapons can be eliminated only by introducing more robust conventional ones is misguided because it starts from the premise that nuclear weapons are essential for our security. In reality, though, they play less and less of a role, year after year. The United States has fought many wars in recent decades without ever seriously considering the use of nuclear weapons. Syria has repeatedly used chemical weapons against its own civilians, prompting only a conventional military strike from the Trump administration.

Our nuclear arsenal increasingly exists solely to deter the nuclear weapons of other states. In any event, it is difficult to imagine the United States ever engaging in nuclear retaliation. Is it really plausible that the United States would further victimize innocent people in Pyongyang to punish Kim Jong Un for using nuclear weapons against Seoul or Tokyo? Is there any reason to think that Kim Jong Un cares for anyone other than himself and his immediate family? Do we really believe that Kim worries more about dying in a nuclear strike than he does about meeting the same mundane, brutal end as Saddam Hussein or Muammar Gaddafi?

If the world escapes the dangers posed by nuclear weapons, it will not do so because it has solved all of its political problems or because it has developed yet-more-destructive capabilities. It will do so because it has decided that basing our security on nuclear weapons is ultimately doomed to end in catastrophe and that the risks of living without the bomb are smaller than those of living with it. In this world, we will be no more likely to respond to nuclear weapons with our own than we would respond to a genocide by committing one ourselves.

The development of new conventional capabilities and missile defenses, rather than freeing us from these nuclear horrors, has only drawn its bounds tighter by reducing the time available to decision makers and rendering nuclear systems far too complex for any one person to understand. They have also allowed other countries to join in the nuclear fray, creating the possibility of local catastrophes and vastly complicating the dynamics of global deterrence. Advanced conventional weapons, missile defenses, and cyber-enabled weapons don’t promise disarmament, except in trivial ways that leave in place the nuclear dangers.

The solution requires, above all, understanding that our fundamental problems are political—and that we are running out of time to change our institutions and our behavior. We can choose to adapt to new technology and devise other arrangements for our security, or we can simply wait, passively accepting our fate like so many socie-ties throughout history that hoped they would survive the rapid technological changes around them—but did not. Technological solutions are a dangerous fantasy, a convenient excuse for our lack of will to take steps in line with the dangers we face. In the end, advances in technology won’t save us; only advances in ourselves can do that.