Since Russia launched its full-scale invasion of Ukraine in February 2022, the United States has provided Kyiv with extensive military aid. But that aid has long been subject to restrictions. Some have to do with the type of equipment provided, such as limits on transfers of long-range missiles or aircraft. Others constrain how U.S. weapons can be used. Washington has designed many of these restrictions to limit Ukraine’s ability to hit targets far behind the front, fearing that deep strikes would be unduly escalatory.

That position has been controversial. Both Ukrainian officials and outside critics argue that the Biden administration exaggerates the risk of Russian escalation, needlessly denying Kyiv critical military capabilities. Before making an assessment, it is important to consider just how militarily valuable deep strikes would be for Ukraine—how, if at all, the war’s prognosis would change if the United States were to lift its restrictions and Ukraine were to acquire the necessary capabilities. Only then would it be possible to judge whether the military benefits are worth the escalatory risk.

From a strictly military perspective, restrictions never help. Giving Ukraine the means and permission to launch attacks deep into Russian-held territory would surely improve Ukrainian combat power. But the difference is unlikely to be decisive. To achieve a game-changing effect, Ukraine would need to combine these strikes with tightly coordinated ground maneuver on a scale that its forces have been unable to master so far in this war. Otherwise, the benefits Ukraine could draw from additional deep strike capability would probably not be enough to turn the tide.

SHAPING THE BATTLEFIELD?

The conflict in Ukraine has been a war of attrition for more than a year now. Both sides have adopted the kind of deep, prepared defenses that historically have proved very difficult to break through. It is still possible to take ground, especially for the numerically superior Russians, but progress is slow and costly in both lives and materiel. Ukraine would need far more than modest improvements in capability to overcome Russian defenses and turn the present war of position into a war of maneuver, in which ground can be gained quickly, at tolerable cost, and on a large scale.

Ukraine’s recent advances in the Kursk region of Russia illustrate the difficulty of turning the tide of the war. Ukraine attacked an unusually ill-prepared section of the Russian front, which enabled Ukrainian forces to take ground quickly. But as Russian reserves have arrived, the Ukrainian advance has slowed, and it appears unlikely that Ukraine will make any major breakthrough. The modest seizure of Russian territory may strengthen Ukraine’s bargaining position in negotiations, ease Russian pressure on Ukrainian defenses in the Donbas, or weaken Russian President Vladimir Putin politically, but it is unlikely to change the military picture in a significant way.

There are several ways in which greater Ukrainian deep strike capability might, in principle, change the course of the war. Kyiv would be able to hit distant logistical and command targets, Russian air or naval bases, ground force assembly areas, arms factories or supporting infrastructure, the civilian energy industry, or centers of Russian political control, such as the Kremlin. Striking or threatening to strike such targets would reduce the efficiency of Russia’s offensives, weaken its defensive capability, make military action less sustainable in the long term, and increase the costs of the war for Putin and the Russian leadership class.

Yet there is reason to question how significant any of these effects may be. For starters, deep strike systems are expensive. Cheap drones cannot fly hundreds of miles to reach distant targets. This capability instead demands larger, more sophisticated, and more costly weapons. U.S. aid to Ukraine is limited by strict spending caps, making such systems impossible to provide without curtailing other kinds of provisions. A fleet of just 36 U.S. F-16 fighter jets, for example, would eat up $3 billion of the $60 billion allocated to Ukraine in the most recent aid bill.

If expensive systems produced disproportionate results, their cost might be worth it. But to hit distant targets requires precision guidance—a technology vulnerable to countermeasures. When one side has introduced new capabilities during this war, the other side has responded quickly by deploying technical countermeasures and operational adaptations. Even though expensive precision weapons such as the HIMARS missile or Excalibur guided artillery shell were highly effective when Ukrainian troops first began to use them, for example, they lost much of their efficacy within just a few weeks as Russian forces adapted.

Deep strikes would have a similarly short window in which they could make a real difference. Ukraine would need to deploy its new capabilities on a large scale and all at once, integrating them with ground maneuver to break through Russian lines. Per U.S. military doctrine, the deep strikes would “shape the battlefield” by temporarily cutting off support for key enemy fronts, creating an opportunity to strike those fronts with concentrated ground and air forces before the enemy could recover and respond.

Executing all this is far from easy. In its summer 2023 offensive, the Ukrainian military showed no ability to coordinate forces on anything like the scale needed for a decisive breakthrough. Longer-range weapons would make this coordination even more complicated. In 2023, Ukrainian leaders argued that large-scale synchronization was impossible while fighting an enemy with modern drones and artillery; many U.S. officers thought the problem was insufficient Ukrainian training. Either way, though, there is little reason to expect that a dynamic, large-scale integration of deep strikes and close combat would be more feasible for Ukraine now than a simpler version was a year ago. Without such an operation, however, a small number of expensive deep strike systems would consume a large share of the U.S. aid budget in exchange for a marginal increase in Ukraine’s ability to inflict casualties in positional warfare.

STRATEGIC BOMBING?

Ground-force synchronization is not the only way deep strikes could reshape the war. Rather than aiming at Russian military forces directly, Ukraine could use these capabilities to target war-supporting Russian industries, such as tank and ammunition manufacturing; oil refineries, power stations, and other parts of the country’s energy infrastructure; or centers of political control. The goal would be either to undermine Russia’s ability to sustain its war effort or to drain its will to do so.

Yet the historical record of such targeting is not encouraging. Allied forces launched massive bombing campaigns to destroy German and Japanese cities and industrial sites in World War II. U.S. forces repeatedly hit North Korean cities and infrastructure in the Korean War and North Vietnamese cities and infrastructure in the Vietnam War. The strikes never broke the targeted country’s resolve. The atomic bombings of Hiroshima and Nagasaki may have been decisive in pushing Japan to surrender in 1945, but no one is proposing a nuclear attack on Russian cities today.

More recent and smaller-scale precision bombing campaigns have fared little better. The United States and its allies conducted such operations in Iraq in 1991 and 2003, Serbia in 1999, Afghanistan in 2001, and Libya in 2011. Iran and Iraq struck each other’s cities during the Iran-Iraq War of 1980–88. Russia has undertaken a strategic bombing campaign against Ukrainian cities and energy infrastructure since the winter of 2022–23. In none of these cases have the results been promising. Russia’s attacks on Ukraine’s energy system, if anything, have hardened the Ukrainian will to fight. In Afghanistan, Iraq, and Libya, too, strategic bombing failed to induce concessions; it took synchronized combinations of air and ground combat to secure Western war aims. Iraq’s threats to attack Iranian cities with chemical weapons helped push Iran to accept a UN-brokered cease-fire in 1988, but chemical warfare against Russia is not on the table today. The evidence is mixed in the case of Serbia in 1999. The Serbian leader Slobodan Milosevic conceded to most of NATO’s demands after a months-long NATO bombing campaign, but it is difficult to disentangle the effects of the bombing from the effects of years of sanctions, which had taken a heavier toll on the Serbian economy than the bombing had. Decades of history thus offer little basis for confidence that Ukraine could break Russia’s will to fight with a modest bombing campaign.

Some analysts consider the most beneficial outcome of strategic bombing to be its ability to divert an enemy’s military effort away from land warfare and into air defense, or its ability to destroy an enemy’s weapons production, thereby weakening its fielded forces. But to do either on a sufficiently large scale is a massive undertaking. During World War II, the Allied powers used more than 710,000 aircraft to drop over two million tons of bombs on Germany over three and a half years—and German weapons production still rose between January 1942 and July 1944. Only in the war’s final months, after the German air force had been largely destroyed, did this enormous campaign incapacitate German ground forces. Even with the benefit of modern technology, no plausible transfer of Western weapons today would enable Ukraine to carry out a campaign that is remotely comparable in scope. If it somehow did, Russia has access to foreign weapons and equipment—courtesy of countries such as North Korea and China—that would remain beyond the reach of Ukrainian strikes.

RISK ASSESSMENT

Of course, conducting more extensive deep strikes would help Ukraine. Damaging factories or infrastructure inside Russia might help boost Ukrainian morale, for example, as a small U.S. bombing raid against Tokyo in 1942 did for American morale in World War II. But now, as then, the capability will not transform the military situation on the ground.

With that in mind, Kyiv’s partners should now ask whether the modest military benefits are worth the escalatory risk. The answer will turn on assessments of the likelihood of expanding the conflict and on the risk tolerance of Western governments and publics. The latter is ultimately a value judgment; military analysis alone cannot dictate where to draw the line. What it can do is forecast the battlefield consequences of policy decisions. If the West lifts its restraints on Ukrainian deep strike capability, the consequences are unlikely to include a decisive change in the trajectory of the war.