Shortly after the West rebuked Russia for its 2022 invasion of Ukraine and imposed financial sanctions of unprecedented scope, Russian President Vladimir Putin announced that he was putting his country’s nuclear forces on high alert. The Kremlin has issued many more nuclear threats, some oblique and some explicit, since then.

The mere possibility that Putin might make good on these threats raises great concern. Even before the war in Ukraine, Russia had reversed its longtime “no first use” policy, under which it claimed it would never go nuclear unless the enemy did so first. Some now believe Russia has switched to an approach known as “escalate to de-escalate,” which holds that nuclear escalation can defuse a crisis by proving one’s commitment to destruction and forcing the enemy to capitulate. In Ukraine, that could mean using a handful of tactical, low-yield nuclear weapons on the battlefield—which CIA Director William Burns and a number of high-ranking U.S. military leaders have warned is possible. Putin, for his part, has merely said that Russia reserves the right to use nuclear weapons if confronting an “existential” threat.

What constitutes an existential threat, however, is not clearly delineated in Russian strategic doctrine. It lies in the eye of the beholder—in this case, Putin, who retains full control of Russia’s nuclear arsenal, albeit subject to a supposed requirement that Russia’s defense minister and the chief of the general staff of the armed forces authenticate his launch orders. The answer, in other words, comes down to one of the most opaque aspects of the current crisis: the state of Putin’s mind and his outlook on the world.

Much of the debate around Putin’s psychological disposition has centered on whether the Russian president acts rationally. That discussion is an important one, but it has at times lacked nuance. A sounder approach may be to ask what common psychological biases and pathologies, based on behavioral theory and research, shape people’s perception of nuclear war—and how they may apply to the Russian leader. How far Putin will take his nuclear brinkmanship remains anybody’s guess. But a combination of known psychological and cognitive biases, combined with some psychological tendencies characteristic of Putin, could prove extraordinarily dangerous if he feels backed into a corner, with potentially massive implications as Ukraine begins its spring offensive.

SHIELD AND SWORD

A nuclear shadow has hung over the Ukraine conflict from the start. Although the war has been fought by conventional means, Putin would not have started it without his nuclear shield. And his repeated attempts at nuclear coercion have been a central element of his plan to achieve several war aims, although that strategy has met with decidedly mixed success.

For one thing, Putin has raised the specter of nuclear war to deter direct NATO intervention on the battlefield. This has undoubtedly worked, and it provides an ominous lesson to other countries—nuclear and nonnuclear alike—about the room for aggression below the nuclear threshold.

Putin also hoped that his threats would deter, or at least cap, the provision of Western military aid to Ukraine. The level of aid indeed appears to be limited by fears of nuclear escalation. But the success of Russia’s coercive efforts on this front is declining. A coalition of backers has slowly increased its level of support to Ukraine and has accepted at least some risk of nuclear escalation to do so. Its latest step—a joint allied program to train Ukrainian pilots on F-16 fighter jets—even opens the door to a future transfer of these highly coveted fighter aircraft.

Putin’s saber rattling has likewise failed to halt the expansion of NATO. Finland has already abandoned its long-standing neutrality and joined the alliance, adding another 800 miles to NATO’s border with Russia. Sweden is only awaiting Turkey’s approval to join next.

Last, and perhaps most important, is Putin’s desire to force Ukraine’s surrender. To support that goal, the Russian president may yet be tempted to engage in more overt nuclear brinkmanship. Overall, in a war that has gone very badly for him, nuclear weapons remain crucial to his plans and future moves.

BLIND SPOTS

In weighing nuclear use, Putin would confront difficult but inevitable tradeoffs between conflicting goals. Nuclear escalation might, in his mind, hasten victory in a grueling war, but he must weigh any potential short-term benefits against the assured harms, both immediate and long term. These include destruction, loss of life, and punishing retaliatory strikes beyond Ukraine’s borders, as the Biden administration and its allies have threatened, as well as irreversible damage—to survivors, to the environment, to the norms of domestic and international politics, to the very integrity of human civilization. This equation, if given due thought and effort, would not encourage nuclear escalation.

The trouble, according to both psychological research and historical evidence, is that people generally struggle to weigh conflicting risks and benefits—including those involving nuclear weapons. Faced with complexity, we simplify, narrowing our focus until a clear choice emerges. Rather than creating a common currency, so to speak, with which to weigh diverse values and objectives in a compensatory manner, we order our goals by priority and focus on achieving the one that is the highest. As the scholars Kenneth Hammond and Jeryl Mumpower have observed, when our values compete, we retreat into “singular emphasis on our favorite value.” This narrowing of attention is known as “the prominence effect.”

Like a spotlight, the prominence effect focuses our attention on what we perceive as the most inherently important attributes of a decision, causing those attributes to assume great and sometimes extreme priority, making a difficult choice appear much easier. In politics, this helps explain the phenomenon of single-issue voters who value a candidate’s position on, say, gun control, abortion, or immigration to the exclusion of any other factor.

The prominence effect has been shown to lead people to disregard humanitarian values, such as protecting human lives or the environment, in favor of more imminent and defensible security goals or salient personal objectives. (Single-issue voting, for example, is particularly common in matters of national security, especially under conditions of threat.) In decisions on the development and use of nuclear weapons, leaders must weigh short-term military and political benefits against vast but hard-to-assess human, social, cultural, and political consequences. The difficulty of doing so in any even-handed way may push long-term consequences, no matter how great their intrinsic importance, outside the spotlight of attention and thus lower the threshold for escalating conflict when under threat or in the face of losses.

THE DEADLY ARITHMETIC OF COMPASSION

Another cognitive bias tipping the scale is our difficulty in computing mass suffering. Most people are familiar with the aphorism that “the death of one man is a tragedy; the death of a million is a statistic,” even if not all of them realize that the saying is frequently attributed to the mass-murdering Soviet leader Joseph Stalin. Like other dictums of the sort—“statistics are human beings with the tears dried off”—it captures well our flawed arithmetic of compassion. We care about individual lives, but the fates of nameless, faceless collectives leave us cold, and we become easily inured to large losses of life. This is known as “psychic numbing.”

A single life holds great importance, enough for some people to perform acts of heroism to save complete strangers. It is much harder to appreciate the humanity of groups or entire populations. This defect in our humanitarian accounting has been documented in numerous experiments on life-saving behavior, showing that our intuitive feelings, which we trust to guide us in making all manner of decisions, do not scale up. As the number of lives at risk increases, psychic numbing begins to desensitize us. In some cases, the more who die, the less we care.

Push the numbers high enough, and our feelings of compassion may fade or collapse entirely. A 2015 photograph of Aylan Kurdi, a two-year-old Syrian refugee whose body washed up on a beach in Turkey, generated far more outrage and concern around the world than statistics documenting the hundreds of thousands of deaths in the Syrian civil war up to that point. Larger and larger numbers of dead do not necessarily compound the sense of horror, much less the outrage against those who perpetrate war or genocide. Likewise, a leader willing to countenance nuclear war may not be swayed by the prospect of mass casualties. Past a very low threshold of sensitivity to individual suffering, these numbers may cease to affect decision-making.  

FATAL TRADEOFFS AND CHOICES

Research into the prominence effect and psychic numbing suggests general psychological dynamics that could shape Putin’s decision-making. But what do psychologists know about how people think specifically about the use of nuclear weapons? Empirical evidence on this question is understandably difficult to come by. Many public opinion polls have measured Americans’ support for using nuclear weapons. Yet these polls usually fail to posit the tradeoffs that a leader might face in real life, such as the choice between risking the lives of U.S. soldiers and a nuclear strike that will kill large numbers of foreign noncombatants. This was the dilemma at the heart of U.S. President Harry Truman’s decision to drop nuclear bombs on Hiroshima and Nagasaki in 1945. And this impossible tradeoff is the kind of decision-making environment that allows the prominence effect and psychic numbing to go into overdrive.

In an illuminating 2017 survey experiment, the scholars Scott Sagan and Benjamin Valentino tried to approximate how Americans today would perceive tradeoffs like those Truman once faced. The survey introduced respondents to a hypothetical scenario involving a difficult ground war between the United States and Iran. Respondents were shown a news story that indicated that the war was not going well and estimated that 20,000 additional U.S. military personnel might die if it continued. They were then asked whether they approved of a nuclear strike on Iran’s second-largest city to bring an end to the war and protect the lives of American troops. Participants were told the strike might kill 100,000 Iranian civilians. In a second scenario, the projected death toll was raised to two million Iranian civilians.

The survey results were disturbing. More than half the respondents supported the nuclear option—and, consistent with the effects of psychic numbing, it made little difference whether the strike would kill 100,000 Iranians or two million. Respondents’ willingness to potentially kill millions of civilians to protect 20,000 American service members also points to the prominence they attribute to national security—and the nonprominence of enemy civilian lives.

A study co-authored by one of us (Slovic) replicated Sagan and Valentino’s but probed deeper into the participants’ worldviews. Views on abortion, the death penalty, gun control, and immigration were combined into a single quantitative measure of the degree to which a person generally supported punishing those they viewed as deserving of harsh treatment. The more someone supported punitive policies against others who offended or threatened them (e.g., banning abortion once a heartbeat is detected without exception for rape or incest), the more they supported dropping a nuclear bomb on enemy civilians.

A follow-up survey added questions about racial justice (including on racial disparities in prison sentencing, which often lead to Black people serving harsher sentences than other people who committed the same crimes) and belief in Hell—the ultimate punishment. Respondents who endorsed six or more out of eight ways to punish or restrict the rights of people were almost ten times as likely to approve a nuclear strike on Iranian civilians as those who rejected such punitive approaches. The survey findings have also demonstrated a sense of moral righteousness among supporters of nuclear escalation, who tended to believe that the Iranian victims deserved their fate and that bombing them was ethical. This is consistent with the notion that the perpetrators of harm almost always believe their violent acts to be virtuous. When violence toward the enemy appears not only justified but also virtuous, the threshold for withholding the use of force, or for avoiding escalation, diminishes greatly.

“MEAN, HUNGRY, FEROCIOUS”

It remains impossible to assign a precise probability to a potential nuclear escalation by Russia in Ukraine. It might be easier to predict, however, what one might observe if a Russian nuclear strike in Ukraine is imminent. The nuclear weapons expert Pavel Podvig, for instance, has cited four signs to watch for: more specific nuclear threats from the Kremlin, a rout of Russian forces for which Putin is personally blamed at home, the movement of tactical nuclear weapons from storage into the field, and intercepted Russian communications suggesting possible intent to use nuclear weapons.

But signs that Russia is gearing up for a strike could also be a bluff intended to frighten Ukraine’s allies into standing down. And such signals would only come late in intelligence gathering, meaning there would be little time left to properly evaluate their meaning. Insights from psychological research, however, could shed light on earlier stages of the decision-making process. Factors such as the prominence effect, psychic numbing, and the concept of purportedly “virtuous violence” can help reveal how a leader such as Putin assesses risk—and therefore offer a sense, earlier on, of the relative likelihood that he will go nuclear.

Judging by many of his past statements, Putin’s wish to securely maintain power and his ambition to lead a modern Russian empire into a new golden era are among his most prominent objectives. Both aims will be in jeopardy if the war in Ukraine continues to falter. Still aggrieved by the perceived humiliation of the dissolution of the Soviet Union, Putin sees himself as occupying a unique place in Russian history. He is, to hear him tell it, a latter-day Peter the Great capable of winning back lost lands and restoring his country to its previous position as a major world power. Such narcissistic traits tend to amplify the power of psychic numbing and diminish one’s perception of the value of the lives of others—if those lives are even considered at all.

Putin’s cruelty is legendary and has served him well in acquiring and maintaining power. His vengefulness toward those who criticize him or stand in his way is well documented. He has a long record of imprisoning and assassinating political opponents and sanctioning war crimes in Chechnya and Ukraine. He portrays the war in Ukraine as a righteous fight against Nazis and dehumanizes those who dare criticize him, referring to opponents of his invasion as gnats who fly into one’s mouth and should be spit out on the pavement.

Biographers trace this disposition—the belief that brutality is a survival skill—to Putin’s youth. “Post-siege Leningrad,” the journalist Masha Gessen has written of the Russian president’s hometown, was “a mean, hungry, impoverished place that bred mean, hungry, ferocious children.” The young Putin was commensurately quick to anger. If anyone offended him, a friend of Putin’s told Gessen, he “would immediately jump on the guy, scratch him, bite him, rip his hair out by the clump—do anything at all never to allow anyone to humiliate him in any way.” In addition, Putin was heavily influenced by his experience as a young KGB officer in Dresden in 1989, around the time the Berlin Wall fell. He was shocked by the speed with which the power of the people caused East Germany to implode, and he felt betrayed by the lack of response from Moscow. His subsequent desire for control and wealth, as well as his enduring social network, can be traced back to this early experience of rapid social change.

As a leader, Putin has scaled up his siege mentality into what the journalist Michel Eltchaninoff has described as a perpetual sense of victimhood, a fixation on apparent humiliations and insults directed against Russia. He has developed, over the decades, a vision of the world that is paranoid but coherent. Russia, in his mind, has for centuries been the victim of attempts to contain and dismember it. And in Ukraine, Putin is taking it upon himself, once again, to fight back.

HOPE FOR THE BEST, PREPARE FOR THE WORST

Neither heavy losses on the battlefield nor crippling economic sanctions have led Putin to waver. He appears singularly preoccupied with national security and with his own need for control. He certainly considers his attack on the Ukrainians to be virtuous, going as far as to claim that he is “denazifying” a state led by a Jewish president, a man whose grandfather fought the Nazis in World War II. All of this—the psychic numbing, the extreme prominence of security considerations, the purportedly virtuous violence—portends that he will not seek peace short of Ukrainian surrender.

Of course, it is impossible to precisely assess the odds that Putin will use nuclear weapons in Ukraine. But uncertainty and imprecision are not the same as ignorance. Psychological theory and evidence, backed by the history of warfare, point to a high enough risk that Western governments must plan ahead. They should weigh now their possible responses to an escalation that would come as a shock but should not come as a surprise. Unlike opinion surveys that posit a hypothetical risk to U.S. soldiers, Putin’s vulnerability is real and considerable. Russia’s losses have been staggering, far more than the 20,000-soldier threshold that many members of the American public would say warrants the use of nuclear weapons.

That Putin has not yet taken that step, even in the face of huge casualties, is cold comfort. He may wager that time is still on his side and that even a drawn-out, nonnuclear war of attrition will wear out the Ukrainian war machine and its backers. But his narcissistic focus, concentrated around maintaining his hold on power, could drastically shrink the time horizon. As his generals and mercenaries continue their infighting, he may take more risks to end the war sooner. He is a man whom humanity will wish it had kept away from its most dangerous weapons.