The Underappreciated Risks of
Catastrophic Escalation Over Ukraine

John J. Mearsheimer / Foreign Affairs

(August 17, 2022) — Western policymakers appear to have reached a consensus about the war in Ukraine: the conflict will settle into a prolonged stalemate, and eventually a weakened Russia will accept a peace agreement that favors the United States and its NATO allies, as well as Ukraine.

Although officials recognize that both Washington and Moscow may escalate to gain an advantage or to prevent defeat, they assume that catastrophic escalation can be avoided. Few imagine that US forces will become directly involved in the fighting or that Russia will dare use nuclear weapons.

Washington and its allies are being much too cavalier. Although disastrous escalation may be avoided, the warring parties’ ability to manage that danger is far from certain. The risk of it is substantially greater than the conventional wisdom holds. And given that the consequences of escalation could include a major war in Europe and possibly even nuclear annihilation, there is good reason for extra concern.

To understand the dynamics of escalation in Ukraine, start with each side’s goals. Since the war began, both Moscow and Washington have raised their ambitions significantly, and both are now deeply committed to winning the war and achieving formidable political aims. As a result, each side has powerful incentives to find ways to prevail and, more important, to avoid losing.

In practice, this means that the United States might join the fighting either if it is desperate to win or to prevent Ukraine from losing, while Russia might use nuclear weapons if it is desperate to win or faces imminent defeat, which would be likely if US forces were drawn into the fighting.

Furthermore, given each side’s determination to achieve its goals, there is little chance of a meaningful compromise. The maximalist thinking that now prevails in both Washington and Moscow gives each side even more reason to win on the battlefield so that it can dictate the terms of the eventual peace.

In effect, the absence of a possible diplomatic solution provides an added incentive for both sides to climb up the escalation ladder. What lies further up the rungs could be something truly catastrophic: a level of death and destruction exceeding that of World War II.

Aiming High
The United States and its allies initially backed Ukraine to prevent a Russian victory and help negotiate a favorable end to the fighting. But once the Ukrainian military began hammering Russian forces, especially around Kyiv, the Biden administration shifted course and committed itself to helping Ukraine win the war against Russia. It also sought to severely damage Russia’s economy by imposing unprecedented sanctions.

As Secretary of Defense Lloyd Austin explained US goals in April, “We want to see Russia weakened to the degree that it can’t do the kinds of things that it has done in invading Ukraine.” In effect, the United States announced its intention to knock Russia out of the ranks of great powers.

What’s more, the United States has tied its own reputation to the outcome of the conflict. US President Joe Biden has labelled Russia’s war in Ukraine a “genocide” and accused Russian President Vladimir Putin of being a “war criminal” who should face a “war crimes trial.”

Presidential proclamations such as these make it hard to imagine Washington backing down; if Russia prevailed in Ukraine, the United States’ position in the world would suffer a serious blow.

Russian ambitions have also expanded. Contrary to the conventional wisdom in the West, Moscow did not invade Ukraine to conquer it and make it part of a Greater Russia. It was principally concerned with preventing Ukraine from becoming a Western bulwark on the Russian border.

Putin and his advisers were especially concerned about Ukraine eventually joining NATO. Russian Foreign Minister Sergey Lavrov made the point succinctly in mid-January, saying at a press conference, “the key to everything is the guarantee that NATO will not expand eastward.”

For Russian leaders, the prospect of Ukrainian membership in NATO is, as Putin himself put it before the invasion, “a direct threat to Russian security”—one that could be eliminated only by going to war and turning Ukraine into a neutral or failed state.

Toward that end, it appears that Russia’s territorial goals have expanded markedly since the war started. Until the eve of the invasion, Russia was committed to implementing the Minsk II agreement, which would have kept the Donbas as part of Ukraine.

Over the course of the war, however, Russia has captured large swaths of territory in eastern and southern Ukraine, and there is growing evidence that Putinnow intends to annex all or most of that land, which would effectively turn what is left of Ukraine into a dysfunctional rump state.

The threat to Russia today is even greater than it was before the war, mainly because the Biden administration is now determined to roll back Russia’s territorial gains and permanently cripple Russian power. Making matters even worse for Moscow, Finland and Sweden are joining NATO, and Ukraine is better armed and more closely allied with the West.

Moscow cannot afford to lose in Ukraine, and it will use every means available to avoid defeat. Putin appears confident that Russia will ultimately prevail against Ukraine and its Western backers. “Today, we hear that they want to defeat us on the battlefield,” he said in early July. “What can you say? Let them try. The goals of the special military operation will be achieved. There are no doubts about that.”

Ukraine, for its part, has the same goals as the Biden administration. The Ukrainians are bent on recapturing territory lost to Russia — including Crimea — and a weaker Russia is certainly less threatening to Ukraine. Furthermore, they are confident that they can win, as Ukrainian Defense Minister Oleksii Reznikov made clear in mid-July, when he said, “Russia can definitely be defeated, and Ukraine has already shown how.”

His US counterpart apparently agrees. “Our assistance is making a real difference on the ground,” Austin said in a late July speech. “Russia thinks that it can outlast Ukraine—and outlast us. But that’s just the latest in Russia’s string of miscalculations.”

In essence, Kyiv, Washington, and Moscow are all deeply committed to winning at the expense of their adversary, which leaves little room for compromise. Neither Ukraine nor the United States, for example, is likely to accept a neutral Ukraine; in fact, Ukraine is becoming more closely tied with the West by the day. Nor is Russia likely to return all or even most of the territory it has taken from Ukraine, especially since the animosities that have fueled the conflict in the Donbas between pro-Russian separatists and the Ukrainian government for the past eight years are more intense than ever.

These conflicting interests explain why so many observers believe that a negotiated settlement will not happen any time soon and thus foresee a bloody stalemate. They are right about that. But observers are underestimating the potential for catastrophic escalation that is built into a protracted war in Ukraine.

There are three basic routes to escalation inherent in the conduct of war: one or both sides deliberately escalate to win, one or both sides deliberately escalate to prevent defeat, or the fighting escalates not by deliberate choice but inadvertently. Each pathway holds the potential to bring the United States into the fighting or lead Russia to use nuclear weapons, and possibly both.

Enter America
Once the Biden administration concluded that Russia could be beaten in Ukraine, it sent more (and more powerful) arms to Kyiv. The West began increasing Ukraine’s offensive capability by sending weapons such as the HIMARS multiple launch rocket system, in addition to “defensive” ones such as the Javelin antitank missile.

Over time, both the lethality and quantity of the weaponry has increased. Consider that in March, Washington vetoed a plan to transfer Poland’s MiG-29 fighter jets to Ukraine on the grounds that doing so might escalate the fight, but in July it raised no objections when Slovakia announced that it was considering sending the same planes to Kyiv. The United States is also contemplating giving its own F-15s and F-16s to Ukraine.

The United States and its allies are also training the Ukrainian military and providing it with vital intelligence that it is using to destroy key Russian targets. Moreover, as The New York Times has reported, the West has “a stealthy network of commandos and spies” on the ground inside Ukraine.

Washington may not be directly engaged in the fighting, but it is deeply involved in the war. And it is now just a short step away from having its own soldiers pulling triggers and its own pilots pressing buttons.

The US military could get involved in the fighting in a variety of ways. Consider a situation where the war drags on for a year or more, and there is neither a diplomatic solution in sight nor a feasible path to a Ukrainian victory.

At the same time, Washington is desperate to end the war—perhaps because it needs to focus on containing China or because the economic costs of backing Ukraine are causing political problems at home and in Europe. In those circumstances, US policymakers would have every reason to consider taking riskier steps — such as imposing a no-fly zone over Ukraine or inserting small contingents of US ground forces — to help Ukraine defeat Russia.

A more likely scenario for US intervention would come about if the Ukrainian army began to collapse and Russia seemed likely to win a major victory. In that case, given the Biden administration’s deep commitment to preventing that outcome, the United States could try to turn the tide by getting directly involved in the fighting.

One can easily imagine US officials believing that their country’s credibility was at stake and convincing themselves that a limited use of force would save Ukraine without prompting Putin to use nuclear weapons. Alternatively, a desperate Ukraine might launch large-scale attacks against Russian towns and cities, hoping that such escalation would provoke a massive Russian response that would finally force the United States to join the fighting.

The final scenario for American involvement entails inadvertent escalation: without wanting to, Washington gets drawn into the war by an unforeseen event that spirals upward. Perhaps US and Russian fighter jets, which have come into close contact over the Baltic Sea, accidentally collide. Such an incident could easily escalate, given the high levels of fear on both sides, the lack of communication, and the mutual demonization.

Or maybe Lithuania blocks the passage of sanctioned goods traveling through its territory as they make their way from Russia to Kaliningrad, the Russian enclave that is separated from the rest of the country. Lithuania did just that in mid-June, but it backed off in mid-July, after Moscow made it clear it was contemplating “harsh measures” to end what it considered an illegal blockade.

The Lithuanian foreign ministry, however, has resisted lifting the blockade completely. Since Lithuania is a NATO member, the United States would almost certainly come to its defense if Russia attacked the country.

Or perhaps Russia destroys a building in Kyiv or a training site somewhere in Ukraine and unintentionally kills a substantial number of Americans, such as aid workers, intelligence operatives, or military advisers. The Biden administration, facing a public uproar at home, decides it must retaliate and strikes Russian targets, which then leads to a tit-for-tat exchange between the two sides.

Lastly, there is a chance that the fighting in southern Ukraine will damage the Russian-controlled Zaporizhzhya nuclear power plant, the largest in Europe, to the point where it spews radiation around the region, leading Russia to respond in kind.

Dmitry Medvedev, the former Russian president and prime minister, delivered an ominous response to that possibility, saying in August, “Don’t forget that there are nuclear sites in the European Union, too. And incidents are possible there as well.” Should Russia strike a European nuclear reactor, the United States would almost certainly enter the fighting.

Of course, Moscow, too, could instigate the escalation. One cannot discount the possibility that Russia, desperate to stop the flow of Western military aid into Ukraine, would strike the countries through which the bulk of it passes: Poland or Romania, both of which are NATO members.

There is also a chance that Russia might launch a massive cyberattack against one or more European countries aiding Ukraine, causing great damage to its critical infrastructure. Such an attack could prompt the United States to launch a retaliatory cyberattack against Russia.

If it succeeded, Moscow might respond militarily; if it failed, Washington might decide that the only way to punish Russia would be to hit it directly. Such scenarios sound far-fetched, but they are not impossible. And they are merely a few of the many pathways by which what is now a local war might morph into something much larger and more dangerous.

Going Nuclear
Although Russia’s military has done enormous damage to Ukraine, Moscow has, so far, been reluctant to escalate to win the war. Putin has not expanded the size of his force through large-scale conscription. Nor has he targeted Ukraine’s electrical grid, which would be relatively easy to do and would inflict massive damage on that country.

Indeed, many Russians have taken him to task for not waging the war more vigorously. Putin has acknowledged this criticism but has let it be known that he would escalate if necessary. “We haven’t even yet started anything in earnest,” he said in July, suggesting that Russia could and would do more if the military situation deteriorated.

What about the ultimate form of escalation? There are three circumstances in which Putin might use nuclear weapons. The first would be if the United States and its NATO allies entered the fight. Not only would that development markedly shift the military balance against Russia, greatly increasing the likelihood of its defeat, but it would also mean that Russia would be fighting a great-power war on its doorstep that could easily spill into its territory.

Russian leaders would surely think their survival was at risk, giving them a powerful incentive to use nuclear weapons to rescue the situation. At a minimum, they would consider demonstration strikes intended to convince the West to back off. Whether such a step would end the war or lead it to escalate out of control is impossible to know in advance.

In his February 24 speech announcing the invasion, Putin strongly hinted that he would turn to nuclear weapons if the United States and its allies entered the war. Addressing “those who may be tempted to interfere,” he said, “they must know that Russia will respond immediately, and the consequences will be such as you have never seen in your entire history.”

His warning was not lost on Avril Haines, the US director of national intelligence, who predicted in May that Putin might use nuclear weapons if NATO “is either intervening or about to intervene,” in good part because that “would obviously contribute to a perception that he is about to lose the war in Ukraine.”

In the second nuclear scenario, Ukraine turns the tide on the battlefield by itself, without direct US involvement. If Ukrainian forces were poised to defeat the Russian army and take back their country’s lost territory, there is little doubt that Moscow could easily view this outcome as an existential threat that required a nuclear response. After all, Putin and his advisers were sufficiently alarmed by Kyiv’s growing alignment with the West that they deliberately chose to attack Ukraine, despite clear warnings from the United States and its allies about the grave consequences that Russia would face.

Unlike in the first scenario, Moscow would be employing nuclear weapons not in the context of a war with the United States but against Ukraine. It would do so with little fear of nuclear retaliation, since Kyiv has no nuclear weapons and since Washington would have no interest in starting a nuclear war. The absence of a clear retaliatory threat would make it easier for Putin to contemplate nuclear use.

In the third scenario, the war settles into a protracted stalemate that has no diplomatic solution and becomes exceedingly costly for Moscow. Desperate to end the conflict on favorable terms, Putin might pursue nuclear escalation to win. As with the previous scenario, where he escalates to avoid defeat, US nuclear retaliation would be highly unlikely. In both scenarios, Russia is likely to use tactical nuclear weapons against a small set of military targets, at least initially. It could strike towns and cities in later attacks if necessary.

Gaining a military advantage would be one aim of the strategy, but the more important one would be to deal a game-changing blow—to create such fear in the West that the United States and its allies move quickly to end the conflict on terms favorable to Moscow.

No wonder William Burns, the director of the CIA, remarked in April, “None of us can take lightly the threat posed by a potential resort to tactical nuclear weapons or low-yield nuclear weapons.”

Courting Catastrophe
One might concede that although one of these catastrophic scenarios could theoretically happen, the chances are small and thus should be of little concern. After all, leaders on both sides have powerful incentives to keep the Americans out of the fighting and avoid even limited nuclear use, not to mention an actual nuclear war.

If only one could be so sanguine. In fact, the conventional view vastly understates the dangers of escalation in Ukraine. For starters, wars tend to have a logic of their own, which makes it difficult to predict their course. Anyone who says that they know with confidence what path the war in Ukraine will take is mistaken.

The dynamics of escalation in wartime are similarly hard to predict or control, which should serve as a warning to those who are confident that events in Ukraine can be managed. Furthermore, as the Prussian military theorist Carl von Clausewitz recognized, nationalism encourages modern wars to escalate to their most extreme form, especially when the stakes are high for both sides.

That is not to say that wars cannot be kept limited, but doing so is not easy. Finally, given the staggering costs of a great-power nuclear war, even a small chance of it occurring should make everyone think long and hard about where this conflict might be headed.

This perilous situation creates a powerful incentive to find a diplomatic solution to the war. Regrettably, however, there is no political settlement in sight, as both sides are firmly committed to war aims that make compromise almost impossible.

The Biden administration should have worked with Russia to settle the Ukraine crisis before war broke out in February. It is too late now to strike a deal. Russia, Ukraine, and the West are stuck in a terrible situation with no obvious way out. One can only hope that leaders on both sides will manage the war in ways that avoid catastrophic escalation. For the tens of millions of people whose lives are at stake, however, that is cold comfort.

John J. Mearsheimer is R. Wendell Harrison Distinguished Service Professor of Political Science at the University of Chicago.

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