In Vladimir Putin’s war of aggression against Ukraine, could he conduct a nuclear strike on a Ukrainian city? Unfortunately, but unquestionably, the answer is: yes. As CIA director William Burns said last week directly when asked this question: “…none of us can take lightly the threat posed by a potential resort to … nuclear weapons.” As Ukrainian president Volodymyr Zelenskyy told CNN in an interview aired last Saturday: “We shouldn’t wait for the moment when Russia decides to use nuclear weapons … For [Putin], life of the people is nothing.”

Russia certainly has an arsenal of nuclear-tipped Iskander missiles that could deliver a tactical nuclear warhead with a yield of 10-15 kilotons to targets within a range of 300 miles. 15 kilotons is roughly the size of the blast of the atomic bombs the United States dropped on the Japanese cities of Hiroshima and Nagasaki to end World War II.

Will Putin order a nuclear strike on a Ukrainian city? I’m betting not. But the reason I remain hopeful is that I’m expecting that the combination of Russian success in the battle that is shaping up in the Donbas, on the one hand, and increasing pain caused by the U.S.-led and continually tightening noose around Russia’s economy and society, on the other, will lead to a stalemate where both Russia and Ukraine will settle for a ceasefire. This could include a negotiated agreement along a line of control—similar to the armistice at the 38th parallel that ended the Korean War in 1953. Or it could be something less formal like the line of contact between Russia-supported separatists in the Donbas and Luhansk, and Kyiv along which there has been sporadic, low-intensity fighting since Russia seized Crimea in 2014.

Additionally, with the West flooding weapons into Ukraine, if Ukraine were to “win” the battle for the Donbas, as many Ukrainians now imagine they could, and indeed if they could push Russian forces entirely out of occupied Ukrainian territory, then what? In this case, my bet about whether Putin goes nuclear flips. To state the central analytic point more clinically: if conditions on the battlefield force Putin to choose between losing and escalating the level of destruction, I’ll give it three-to-one odds that he escalates. 

The evidence and analysis that lead to what may seem to some an alarmist conclusion begin with the judgment that if Putin faces defeat in what some Russians are already calling “Putin’s war,” he knows that this will be the end of his twenty-two-year reign—and probably of his life. Moreover, defeat would ensure that the title of the chapter about him in Russian history would be: failure. The vision of a great Russia that he and his colleagues embrace would be consigned to the dustbin.

Second, while many leaders who have made dumb, even evil choices have subsequently had regrets, Putin has repeatedly demonstrated that he has no reservations about committing mass murder in order to achieve his objectives. At the beginning of his regime, he bombed the Russian city of Grozny into rubble, killing thousands of fellow Russian citizens without blinking an eye. To rule a “liberated” Chechnya, he enlisted a local mafioso who had killed thousands of other Russians whom he has labeled “terrorists.” In Syria, Putin enthusiastically joined the butcher of Syria, Bashar al-Assad, in destroying the people of Aleppo.

Third, while seven decades in which nuclear weapons have never been used in war have left the U.S. military and strategic community with a taboo in which nuclear bombs are essentially no longer seen as weapons of war, we should pause to remember that this was not always the case. In the 1960s and 1970s, when U.S. conventional forces defending Europe were confronting a Soviet adversary that we believed had a five-to-one advantage in conventional forces, how did the United States attempt to deter and defend against an attack by the Evil Empire? We embraced tactical nuclear weapons as our “equalizer.” Indeed, U.S. forces down to the level of company commanders had tactical nuclear weapons they planned to use in the first phase of a Soviet tank attack through the Fulda Gap. Unless met by nuclear attacks, American war planners foresaw Soviet forces reaching the English Channel in less than a week.

This bit of history may help us better understand Russian military commanders and strategists today (as well as Pakistani strategists). For them, tactical nuclear weapons are seen as an essential element in their otherwise losing defense posture.

Finally, can the United States deter Putin from conducting a tactical nuclear strike on a Ukrainian city? And if such a strike killed 10,000 or 20,000 innocent Ukrainians—in contrast to the 140,000 Japanese who died in the U.S. attack on Hiroshima—how would Ukraine or the United States respond? Indeed, if after the first blast, Putin then challenged Zelenskyy to agree to a ceasefire or wait to see what a Ukrainian Nagasaki looks like, what would the United States and NATO do?

Questions like these led strategists in the initial decades of the Cold War to attempt to “think about the unthinkable.” As they have awakened to the threat Putin poses today, analysts at the Pentagon, the White House, and in the wider strategic community are returning to their bookshelves to review again Herman Kahn’s On Thermonuclear War, and On Escalation, Thomas Schelling’s Strategy of Conflict, Bernard Brodie’s Absolute Weapon, and other classics. Many of those now wrestling with difficult choices about responses to Putin’s aggression in Ukraine have been reviewing the script of the most dangerous confrontation in history, the Cuban Missile Crisis of 1962, and reflecting on decisions made by Nikita Khrushchev and John F. Kennedy.

If Putin goes nuclear, what will the United States do? Certainly, the menu will include no good choices. This makes all the more urgent the necessity to end the killing now—even if it leaves Putin in control of enough Ukrainian territory for him to believe that he can spin this to his Russian subjects as a victory. On the larger canvas, while avoiding a third world war, and even worse than that, an ultimate nuclear Armageddon, the United States, its European colleagues, and the remarkably courageous Ukrainian people must do everything we can to ensure that Putin suffers a decisive strategic defeat—and that having survived this horror, Ukraine emerges as a successful, vibrant democracy. If we look carefully at what happened at the end of World War II when West Germany became part of the free world, and East Germany was left under the boot of the Soviet Union, or at the end of the Korean War that divided a free South from a Communist North, there are solid grounds for hope. If the Ukrainian people can be as successful in building their nation as they have been in defeating Putin’s attempt to extinguish it, Ukraine could become the great success story of the next generation.

Graham T. Allison is the Douglas Dillon Professor of Government at the Harvard Kennedy School. He is the former director of Harvard’s Belfer Center and the author of Destined for War: Can America and China Escape Thucydides’s Trap?

Image: Wikimedia Commons.