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Why Washington Should Take Russian Nuclear Threats Seriously

Historically, states have escalated when facing the prospect of imminent defeat—and Putin has a track record of following through on his threats.

Walt-Steve-foreign-policy-columnist20
Stephen M. Walt
By , a columnist at Foreign Policy and the Robert and Renée Belfer professor of international relations at Harvard University.
A column of Russia's Topol intercontinental ballistic missile launchers at Red Square in Moscow, on May 9, 2012, during a Victory Day parade.
A column of Russia's Topol intercontinental ballistic missile launchers at Red Square in Moscow, on May 9, 2012, during a Victory Day parade.
A column of Russia's Topol intercontinental ballistic missile launchers at Red Square in Moscow, on May 9, 2012, during a Victory Day parade. KIRILL KUDRYAVTSEV/AFP/GettyImages

Back in February, I told Roger Cohen of the New York Times that “I find it difficult to believe that any world leader, including Mr. Putin, would seriously contemplate using nuclear weapons in any of the scenarios we have here, for the simple reason that they understand the consequences.” I still think the odds of a nuclear strike are low, but I’m finding it easier to imagine the possibility than I did a couple of months ago.

To its credit, the Biden administration has been somewhat mindful of the risk of escalation, which is one reason the president said early on that he would not send U.S. troops to fight in Ukraine. The assumption behind this policy is that escalatory dangers will be minimized so long as Americans aren’t pulling triggers and actively killing Russians. President Joe Biden & Co. clearly hope this is the case, and military experts such as Lawrence Freedman agree.

There is a sound basis for this position. Avoiding a direct clash of arms between U.S. and Soviet forces was a key unwritten rule of the Cold War, and it was a good one. Had Americans and Soviets started shooting at each other in those years, the risk of accidental or inadvertent escalation would have been considerable. For similar reasons, keeping U.S. forces outside the fray is the right move today.

Back in February, I told Roger Cohen of the New York Times that “I find it difficult to believe that any world leader, including Mr. Putin, would seriously contemplate using nuclear weapons in any of the scenarios we have here, for the simple reason that they understand the consequences.” I still think the odds of a nuclear strike are low, but I’m finding it easier to imagine the possibility than I did a couple of months ago.

To its credit, the Biden administration has been somewhat mindful of the risk of escalation, which is one reason the president said early on that he would not send U.S. troops to fight in Ukraine. The assumption behind this policy is that escalatory dangers will be minimized so long as Americans aren’t pulling triggers and actively killing Russians. President Joe Biden & Co. clearly hope this is the case, and military experts such as Lawrence Freedman agree.

There is a sound basis for this position. Avoiding a direct clash of arms between U.S. and Soviet forces was a key unwritten rule of the Cold War, and it was a good one. Had Americans and Soviets started shooting at each other in those years, the risk of accidental or inadvertent escalation would have been considerable. For similar reasons, keeping U.S. forces outside the fray is the right move today.

During the Vietnam War, America’s inability to achieve victory led it to launch a massive bombing campaign against North Vietnam.

Unfortunately, this policy is not an absolute barrier to unwanted escalation. Historically, states escalate not because of who they happen to be facing on the battlefield but because they are failing to achieve their war aims and may even be facing the possibility of a major defeat.

During World War I, for example, stalemate on the Western Front led both sides to widen the war: The Germans began unrestricted submarine warfare, the British tried to weaken the Ottoman Empire by sponsoring an Arab revolt and attacking Gallipoli, and both sides used poison gas and bombed civilian targets.

During the Vietnam War, America’s inability to achieve victory led it to launch a massive bombing campaign against North Vietnam (known as Operation Rolling Thunder), to employ chemical weapons including the defoliant Agent Orange, and to invade Cambodia in 1970. In short, when a country is losing—or not winning as quickly as it wants—it is likely to consider other options no matter who happens to be pulling the triggers on the other side.

Moreover, the absence of U.S. troops in Ukraine might make escalation more attractive to Russia’s leaders. If Russian President Vladimir Putin and his inner circle were contemplating using one or two tactical nuclear weapons against targets in Ukraine, the fact that U.S. soldiers would not be killed in the attack might remove an additional inhibiting factor.

To be clear: I have no idea if anyone in the Kremlin is thinking seriously along those lines, and this point is not an argument for sending U.S. troops to Ukraine as a deterrent shield. My point is that keeping American personnel out of the fight does not eliminate all incentives to escalate, and it might make nuclear use appear less risky if those other incentives began to loom large in Moscow’s calculations.

I’m also worried because Putin has a track record of issuing warnings and then following through on them. Back in 2008, Russia made it clear that it was dead set against NATO membership for Ukraine or Georgia and that it would do whatever it could to prevent either state from ever joining. War in Georgia broke out shortly thereafter, and the frozen conflict there has kept Georgian membership in NATO off the table ever since. In 2014, Moscow again made it clear that it regarded the ouster of Ukrainian president Viktor Yanukovych—an internal upheaval that the United States embraced—as an equally serious threat. It responded by seizing Crimea and backing a separatist uprising in the Donbas.

And then, in 2021, concerns about Western efforts to arm Ukraine and growing security cooperation between Washington and Kyiv led Putin to put a large army on the border and to threaten military action if his concerns were not addressed. The United States and NATO refused to reconsider the commitment to eventually make Ukraine a member, and we all know what happened next. Instead of dismissing Russian warnings as a bluff, maybe Washington ought to take them seriously.


Russia’s invasion of Ukraine is illegal, immoral, and unjustifiable, but it wasn’t something Putin launched on a whim. That the military campaign has not gone as he expected does not mean he did it for trivial or cavalier reasons. On the contrary: As Putin’s many speeches on this subject have made clear, he and his associates saw Ukraine’s drift into de facto alignment with the United States and NATO as an existential threat—to include the threat of a color revolution in Russia itself—and they almost certainly believed that the time to stop this process was running out.

The failure to take Kyiv has shifted Russian war aims to the east (and probably reduced Moscow’s overall ambitions), but Ukraine’s future geopolitical alignment was the principal casus belli, and that issue has not gone away as far as Moscow is concerned.

Meanwhile, Ukraine’s success on the battlefield has led Kyiv and Washington to expand their own war aims. U.S. Secretary of Defense Lloyd Austin now says he wants to “see Russia weakened,” and Speaker of the House Nancy Pelosi says the United States will back Ukraine “until victory is won.” British Foreign Secretary Liz Truss  has gone even further, saying that NATO needs to “double down” and declaring, “We will keep going further and faster to push Russia out of the whole of Ukraine.”

The Biden administration keeps pouring advanced weapons into Ukraine and has “opened up the pipes” in providing intelligence information, which Ukraine is using to target Russian generals, among other things. Not surprisingly, Ukrainian objectives appear to be rising as well, to include hopes of regaining the territories it has lost since 2014.

Trying to inflict a decisive defeat on Russia creates the circumstances that might encourage a rational leader to contemplate a demonstration strike with a small nuclear weapon.

War aims such as these are emotionally appealing, because many would like to punish Putin for the suffering he’s inflicted on Ukraine. Unfortunately, trying to inflict a decisive defeat on Russia creates precisely the circumstances that would encourage a rational leader to contemplate other options, such as a demonstration strike with a small nuclear weapon. The purpose of such an action would be what the late theorist Thomas Schelling called a “competition in risk-taking”: one side takes an obviously dangerous action in order to demonstrate how much it cares about the issue at hand, and to persuade its opponent(s) to back off.

If Putin thinks he is facing total defeat, a military collapse, or even being removed from power, why wouldn’t he consider raising the stakes? It would be a gamble for sure, but he’s gambled before. And he probably cares more about avoiding those outcomes than the opposing coalition cares about inflicting them on him. He won’t order a large-scale nuclear attack, because that would be suicidal, but a demonstration strike against a non-nuclear adversary, though not without serious risks, is another matter.

To be sure, the use of even a single nuclear weapon could prove just as harmful to Russia as its invasion has been. Violating the nuclear taboo would guarantee that Russia remained a pariah for many years (though that may occur regardless). It could also galvanize additional support for Ukraine and convince China to distance itself from Russia. But it might just as easily spook any number of Western governments and catalyze a rapid end to the conflict. Either way, it would set a very worrisome precedent, and no one can be certain that even very limited use would stay that way.

Washington has every reason, therefore, to avoid this alarming scenario. No matter how much one might want to see Russia decisively defeated, there are limits to how far one can safely push a nuclear-armed adversary. As the security expert Sam Roggeveen made clear in an essay in March, “If Russia is hurtling towards economic and military collapse, Western leaders ought to be thinking about how to ratchet down the pressure.” And they can do so with a certain confidence, because the war has in fact been a catastrophe for Russia and will hasten its decline no matter what the West does now.

The war in Ukraine is a tragedy, for the citizens of Ukraine most of all. It will be even more tragic if Russia tries to salvage its waning fortunes by moving up the escalation ladder. I still think this possibility is unlikely, and I hope those who think Putin is more likely to declare victory and try to de-escalate are correct. But I’d be a lot more comfortable if Western leaders took the possibility of nuclear use more seriously, ended their loose talk about war aims, and focused more attention on ending the war than on achieving an ill-defined but supposedly decisive victory.

As I’ve noted before, ending this war requires all parties to settle for less than they originally wanted, and that includes the United States.

Stephen M. Walt is a columnist at Foreign Policy and the Robert and Renée Belfer professor of international relations at Harvard University.

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