Ukrainian military exercises in the Dnipropetrovsk region, Ukraine, August 2023
Ukrainian military exercises in the Dnipropetrovsk region, Ukraine, August 2023
Viacheslav Ratynskyi / Reuters

Since the moment Russia invaded Ukraine in February 2022, the specter of escalation has loomed over the war. For Ukrainian citizens and soldiers, the war is a grueling, horrific, daily reality that has already escalated in notable ways; in August, Kyiv ramped up strikes in Russia, and Moscow has resumed its campaign against Ukrainian grain exports through the Black Sea. Seen another way, however, many of the most feared escalation scenarios have not occurred, most notably a large-scale conventional war between NATO and Russia and the use of nuclear weapons.

Eighteen months after the war began, it is time to take stock of its unusual escalation dynamics. Russian President Vladimir Putin has repeatedly hinted that he might go nuclear, raising the prospect that tactical nuclear weapons could be used to destroy military targets, kill Ukrainian civilians, or make a show of force in an uninhabited area. Yet he has not done so. Beyond this most conspicuous missing form of escalation, there are other realms in which various parties have shown restraint—for instance, in the scope of NATO’s surveillance flights or in the details of Russian operations in the Black Sea. Despite ample opportunity to intensify hostilities or to expand the geographic scope of the war, Russia, Ukraine, and Ukraine’s allies have mostly chosen not to do so.

This restraint is often overlooked, and a key reason for it—a gradual approach to the war on all sides—is often misunderstood. Many supporters of Ukraine have criticized the piecemeal delivery of aid and other forms of incrementalism. Indeed, a go-slow approach to expanding military aid to Ukraine has slowed the development of some combat capabilities by Kyiv’s military forces. But the West’s gradual approach has served a vital strategic purpose. It is no accident that the war has avoided certain forms of drastic escalation. The war’s participants, including leaders in Kyiv, have often followed a logic of learning and gradualism, cautiously adopting new weapons and tactics, buying time to assess Russia’s reaction. Even Ukraine has done this in its approach to attacks within Russian territory. Western leaders and Ukraine have allowed what is still, in some important ways, a limited war to emerge organically and through trial and error.

New developments, however, may threaten this dynamic. Russia’s campaign against Ukrainian grain infrastructure and surging Ukrainian attacks within Russia threaten to expand the geographical scope of conflict. The mutiny and subsequent death of Wagner mercenary chief Yevgeny Prigozhin suggest that Russia’s domestic political situation is dynamic and could shift in ways that may encourage Putin to escalate. Ukraine’s counteroffensive, meanwhile, has made some progress but no breakthroughs. Should Ukraine achieve rapid territorial gains, the risks of escalation may sharply increase. To keep escalation in check as the war continues to evolve, Western officials and Ukrainian leaders must resist calls to abandon their gradualist approach. Failure to do so could cause the hard-earned control over escalation to slip away.


Historical comparisons from the past century often inform debates about the risk of escalation. World War I, for instance, started as a local dispute over an assassination, but it quickly ballooned into a pan-European clash that killed 20 million people. The Korean War was initially limited to combat between Pyongyang, Seoul, and Seoul’s foreign partners, but within five months, hundreds of thousands of U.S. and Chinese troops were in direct combat. The United States intended to assist South Vietnam only with military aid and advice, but its involvement evolved into a costly, violent military intervention that lasted a decade.

Conflicts after the end of the Cold War did not feature the same escalation problems. With the end of bipolarity, the West’s adversaries in peripheral countries such as Iraq and Libya did not have great-power backers. These were one-sided affairs. Russia’s invasion of Ukraine therefore harks back to an earlier period when escalation and restraint were potent issues during war.

The gravest form of escalation in Ukraine would involve nuclear weapons. This scenario has been depicted as plausible because employing nuclear weapons could give Putin a decisive edge under certain battlefield conditions or serve as a stark warning to the West. It could even prompt retaliation by NATO, increasing the possibility of a large-scale exchange of nuclear weapons beyond Ukraine’s borders. Every time an ally has provided Kyiv with new surface-to-surface missile systems, air defense systems, armored and tracked vehicles, or fighter jets, cautious voices in the West have warned that these acts risk prompting escalation—including Russian retaliatory strikes outside Ukraine.

To date, this has not happened. The absence of this form of escalation does not mean that analysts have been wrong to fear it. Quite the contrary: a fear of escalation can motivate military commanders and policymakers to make cautious decisions that help prevent it. Early in the war, Kyiv and many of its supporters called for a no-fly zone, but Western leaders refused to impose one, fearing an air-to-air clash between NATO and Russian aircraft. The no-fly zone proposal has faded from public commentary, making the escalation avoided by rejecting it easy to overlook. But this was an important road not taken.

The lesson is clear: anticipating escalation scenarios helps make them less likely to happen. Yet the fear of escalation is not the only factor that has prevented it in Ukraine. Understanding the other reasons why Russia’s invasion has not drastically escalated is essential to avoid escalation, both in this conflict and in others to come.


The absence of nuclear escalation does not mean that analysts have been wrong to fear it.


Public discussions often underrepresent many of the escalation scenarios that have not come to pass. Conspicuously, Russia has not engaged in observable large-scale cyberattacks on targets beyond Ukraine. Moscow has developed a sophisticated cyber-capability and used it to meddle in the 2016 U.S. presidential election. Yet civilian infrastructure or government targets in Western Europe and the United States appear to have been largely spared.

Putin has also abstained from using chemical weapons. The Russian military has a considerable stock of chemical munitions, and chemical attacks by President Bashar al-Assad in Syria have set a dangerous precedent. But Putin has not yet used them in Ukraine.

Some forms of restraint demonstrated by the United States and NATO have received minimal fanfare. The United States has limited visits by senior U.S. military officials to Ukraine to “avoid increasing tensions with Moscow,” as an August assessment of the counteroffensive in The New York Times noted. Few outside Washington notice such moderation. Other forms of restraint related to espionage and covert action are hard to observe. NATO countries routinely conduct surveillance over international waters and their own territories, but according to The New York Times, they “are careful not to stray into the war zone.” A Washington Post report this August on Russian sabotage operations within Poland contained an overlooked revelation: Russia had not even attempted to sabotage the flow of military supplies into Ukraine until a year into the war.

Even Russia’s resumption of its blockade on Ukrainian grain exports in July—a form of escalation in its own way—features elements of restraint. Although its military strikes have targeted grain-related installations, so far Moscow has not overtly attacked civilian grain shipments. NATO countries’ responses to the blockade have also been measured; for now, they have refrained from providing the armed escorts for grain shipments that Ukraine has requested. As the Kremlin expands the scope of its hostilities, it has shown a tendency to also reject more reckless forms of escalation. The missing escalations in Ukraine are analogous to dogs that do not bark: their silence makes them easy to miss.


The puzzle of the missing escalations in Ukraine is, in part, explained by the broader context of this particular war. There are significant incentives for leaders to try to contain the fighting. A direct conventional or nuclear clash between Russia and NATO would clearly be ruinous for both sides, inflicting tremendous economic, political, and military damage. War between major powers in the modern era is incredibly costly. Today’s war in Ukraine and past conflicts during the Cold War share this structural constraint.

The strain on Russia’s military resources almost certainly amplifies the downsides of escalation for Moscow. After its failed bid to swiftly seize Kyiv at the beginning of the war and high rates of equipment loss and casualties, Moscow cannot open new war fronts and achieve anything close to its military objectives in Ukraine. Putin’s decisions over the course of the conflict will need to reflect this reality: if the conflict dramatically widened, he would be playing with a losing hand.

Domestic politics also matter. During the Cold War, restraint toward Communist aggression could be politically fatal. Today’s political environment has changed. Leaders in the democratic West that recklessly invite escalation are probably more likely to lose the next election. It is less clear whether Russia’s domestic political dynamics have blunted or encouraged escalation. Putin must avoid alienating the Russian elites that support him and mobilizing mass dissent. Yet some domestic pressures on Putin incentivize belligerence, namely the war hawks outside government who continually demand more expansive military mobilization or even the use of nuclear weapons.


Another reason for missing escalation involves incrementalism and learning. At critical moments, political leaders and military commanders in the West have chosen gradualism. Going slowly in war often invites criticism. Ukraine’s supporters have at times complained that the United States and its allies have dithered in providing more effective artillery, air defense, and tanks. What looks like indecisiveness, however, can have significant value on the battlefield.

Examples of U.S. and Western European leaders using a slow, incremental approach are not hard to find. Since the early months of the war, NATO members have cautiously and slowly deliberated about providing shoulder-fired missile systems, armored vehicles, missile defense systems, tanks, longer-distance artillery systems, and F-16 training and aircraft. One benefit of this go-slow approach is that it has given intelligence and military experts time to scrutinize how Russia reacts. For example, Washington did not flip a switch and provide M1 Abrams tanks to Ukraine. The idea was debated in public for weeks and internally for longer. Even after approving the M1 Abrams tanks, the United States has slow-rolled their introduction to the battlefield, allowing tanks sent by the British and Germans to go first. Each of these steps can be a painful sacrifice on the battlefield, but they also give analysts time to gauge Putin’s reaction to a potentially explosive U.S. decision.

Kyiv has often been the most vocal critic of the go-slow approach to delivering aid. Yet Ukrainian leaders themselves use gradualism to control escalation when conducting cross-border operations within Russian territory. Since last spring, Ukrainian leaders have incrementally intensified strikes on military supply lines and urban centers within Russia while avoiding taking credit for them. This distancing on Ukraine’s part encourages the Kremlin to respond in a mild, relatively restrained way and avoid the wrath of the public. Ukraine’s Western allies have used distancing as well; for instance, the United States has forbidden its military aid from being used in such operations.

The management of high-risk incidents in Ukraine has been characterized by gradualism, deliberate ambiguity, and political caution. In March 2023, for example, a Russian fighter jet apparently dumped fuel on and collided with a U.S. surveillance drone, sending the drone crashing into the Black Sea. Both sides exchanged blame, with the U.S. military releasing a video to support its account. Yet Washington and Moscow also engaged in deescalatory measures; in public comments, a National Security Council representative suggested that the Russian pilot may have acted on his own accord, and senior U.S. and Russian military officials discussed their views of the incident in a private call.


Escalation control measures that have worked today may need to evolve to keep working tomorrow. Developments over the summer of 2023 may test the limits that have developed. First, Russia’s renewed attacks against Ukrainian grain exports have expanded the geographic boundaries of the war. In August, a Russian drone attacked a port on the Ukrainian side of the Danube River, which forms the border with Romania, a NATO member. Strikes targeting grain infrastructure increase the risk of accidental or unauthorized attacks on civilian shipping or more deadly incidents between military aircraft.

Second, Ukraine appears to be ramping up the scale and intensity of its attacks inside Russia. In July, Ukrainian President Volodymyr Zelensky publicly warned that the war would be “returning to Russia.” This surge may be motivated by a desire to more aggressively degrade Russian logistics during the counteroffensive and to reassure the Ukrainian public that the fight is being taken to Russian territory. Kyiv has also learned from Putin’s mild reaction to earlier cross-border operations. The risk is twofold. A more aggressive campaign within Russia may prompt a harsher reaction. In addition, a widening campaign within Russia may make it easier to expand even farther as more potent Western weaponry becomes available or the war bogs down more.

New developments concerning Putin’s domestic position suggest his decision-making could become more unpredictable. Although some Western commentators and analysts viewed Prigozhin’s rebellion as a positive development, suggesting it indicated a growing appetite for open dissent in Russia, it may also have increased the risk of escalation. Internal dissent could recalibrate Putin’s willingness to accept strategic risk, making him more likely to gamble with escalation as the Hail Mary that would turn the tide of the war and shore up his domestic political support.


Incrementalism can be a painful sacrifice on the battlefield, but it also gives analysts time to gauge Putin’s reactions.


Perhaps Prigozhin’s August death in a plane crash ended the threat to Putin from his inner circle. But if escalation control is largely defined by learning, an increasingly unstable adversary may make moot some of the lessons the West and Ukraine have learned thus far. NATO allies may be less confident about Russia’s reaction to the introduction of F-16 fighter jets into Ukraine’s military operations when the domestic politics in Russia are in flux.

Another wildcard is Ukraine’s counteroffensive. Its sluggish progress is frustrating to Kyiv and its partners, but that pace does inadvertently impose a kind of gradualism. So far, Ukrainian territorial gains have been slow, giving the West time to assess how Putin and the Russian military adapt. Ironically, these limits on escalation could dissolve if Ukraine achieves a decisive battlefield breakthrough. The collapse of the Russian military resistance on one of the conflict’s fronts or the loss of its overland access to Crimea could lead Russian leaders to embrace a new set of escalatory tactics.

Finally, the emergence of a stronger diplomatic process to end the war could reshape the war’s escalation dynamics or even paradoxically encourage escalation. While strengthening diplomatic communication can facilitate better crisis management, peace negotiations can also tempt leaders to escalate. In 1971 during the Vietnam War, for example, U.S. President Richard Nixon and his secretary of state, Henry Kissinger, expanded military operations into Laos ahead of talks with North Vietnam to increase their leverage at the negotiating table.


If gradualism has so far controlled escalation, then leaders need to maintain it and adapt it to meet the evolving challenges of the war. Gradualism is most associated with how the West has provided military weaponry. Washington should continue to move slowly as it decides whether to provide new and more potent systems, such as the Army Tactical Missile System. A cautious incrementalism will also be important when it comes to introducing systems NATO countries have already promised, such as F-16s. Other arenas of the war can also benefit from gradualism. Leaders in the United States and elsewhere should use caution in adopting any new maritime security or surveillance measures in the Black Sea so they can buy time to gauge Russia’s reaction and defuse any incidents. As for Ukraine’s attacks within Russia, Kyiv should go slowly with any expansion in the volume of strikes, targets, or use of new weapons systems.

Countries backing Ukraine also ought to think ahead, designing incremental approaches to Ukraine’s counteroffensive. Should the Ukrainian military achieve a significant breakthrough, Kyiv and its allies should have plans, such as buffer zones for advancing military units, to approach sensitive border areas slowly and cautiously. Western and Ukrainian leaders should also better articulate the strategic value of going slowly, clearly signaling that their gradualism is intentional and motivated by an interest in advancing shared goals while containing the war’s damage. And if negotiations accelerate, leaders in the West and Ukraine should not reach for new escalatory tactics. Any deepening talks with Russia should include proactive and explicit statements about limits that both sides need to respect as the bargaining progresses.

The lack of escalation in Ukraine serves as a reminder that in limited wars, patience is a virtue. A go-slow approach has allowed NATO countries to provide a level of military support that was unthinkable at the war’s start. The risks of escalation have not been overblown. Instead, gradualism has allowed the West to learn—and, in some ways, stretch—the limits of the war.

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