Ukrainian forces retain the initiative in the war but advanced an average of only 90 meters per day on the southern front during the peak of their summer offensive, according to new CSIS analysis. Russia’s extensive fortifications—which include minefields, trench networks, and support from artillery, attack helicopters, and fixed-wing aircraft—have slowed Ukrainian advances. In particular, Russia has expanded the size of its minefields from 120 meters to 500 meters in some areas, making Ukraine the most heavily mined country in the world today. Ukrainian military progress is still possible, but the United States and other Western countries need to provide sustained military aid and other assistance.
The war in Ukraine has become a test of political will and industrial capacity between two competing blocks: allied countries aiding Ukraine, such as the United States and numerous countries in Europe and Asia; and axis countries aiding Russia, such as China, North Korea, and Iran. Despite Ukraine’s efforts to liberate territory illegally seized by Russia, offensive operations have been slow. Some policymakers have erroneously argued that poor Ukrainian strategy has contributed to the slow pace of operations. According to proponents of this view, the Ukrainian military mistakenly focused on conducting operations along multiple fronts rather than on a single front in Zaporizhzhia Oblast.[1]
To better understand military operations in Ukraine, this analysis asks three questions. What is the state of the offense-defense balance in the Ukraine war? What factors have impacted Ukrainian offensive operations? What are the policy implications for the United States and other Western countries?
Ukrainian operations raise the age-old question in warfare about whether it is easier for militaries to seize territory or defend it. This phenomenon is called the “offense-defense balance,” and it refers to the relative strength between the offense and defense in warfare.[2] The main idea is that there are several factors, such as geography, force employment, strategy, and technology, that can influence whether the offense or defense has the advantage.[3] When the offense has the advantage, it is generally easier for an attacking state to destroy its opponent’s military and seize territory than it is to defend one’s own territory. When the defense has the advantage, it is generally easier to hold territory than it is to move forward and seize it.[4]
This analysis utilizes several sources of information. To understand historical rates of advance, this assessment compiles data on offensive campaigns from World War I through Ukraine’s 2023 offensive.[5] It also examines open-source data on fortifications, unit positions, and the attrition of military equipment. In addition, it uses satellite imagery and drone footage of the battlefield in eastern and southern Ukraine to understand the challenges of offensive operations. Finally, the authors conducted interviews with Ukrainian, U.S., and European military officials.
The analysis comes to three main conclusions. First, defense has the advantage in the war. This reality should not come as a major surprise. Carl von Clausewitz wrote in On War that “defense is a stronger form of fighting than attack” and that “the superiority of the defensive (if rightly understood) is very great, far greater than appears at first sight.”[6] Ukrainian forces averaged approximately 90 meters of advance per day during their recent push on the southern front between early June and late August 2023.
Second, the reason for the slow pace of advance was not poor Ukrainian strategic choices, as some have argued.[7] Instead, it was likely caused by a Ukrainian change in force employment, especially the deliberate adoption of small-unit tactics, and the lack of key technology such as fighter aircraft for suppression of enemy air defense and close air support. In addition, Russia constructed substantial defensive fortifications, including minefields, and utilized attack helicopters, fixed-wing aircraft, and unmanned aircraft systems (UASs) against advancing Ukrainian forces.
Third, Ukraine still retains the initiative in the war, and the United States and other Western countries should provide long-term aid packages that help Ukraine strengthen its defense and prevent or deter a Russian counterattack in the future. They should also provide additional aid to help Ukraine on offense to maximize the possibility that it can retake as much territory as possible from Russia. After all, one of the United States’ most significant adversaries, Russia, has been reduced to a second- or third-rate military power without a single U.S. military casualty. As many as 120,000 Russian soldiers have been killed, as well as over 300,000 wounded, and Ukrainian soldiers have destroyed a massive number of Russian weapons systems, from main battle tanks and fighter aircraft to submarines and landing ships.[8] U.S. aid to Ukraine should continue even with U.S. support to Israel likely to grow following the October 2023 Hamas attack, since Russia, Iran, and their partners represent a significant threat to U.S. interests.
The rest of this brief is divided into three sections. The first examines the state of the war and the strength of the defensive advantage in Ukraine. The second section explores the factors contributing to the defensive advantage. The third outlines several policy implications for the United States and other Western countries.
In early June 2023, Ukraine began a counteroffensive to retake territory illegally occupied by Russian forces in the Zaporizhzhia and Donetsk Oblasts. Ukraine retains the operational initiative, but its relatively slow pace of advance and the trade-offs it has made to preserve personnel and equipment indicate that the defense has significant advantages.
This section examines Ukraine’s efforts across three main fronts in summer 2023. First, Ukrainian offensive operations were primarily concentrated along the southern front, in the Zaporizhzhia Oblast and western portions of the Donetsk Oblast. Second, Ukraine was on the offensive in various locations along the eastern front in the Donetsk Oblast. Third Ukraine conducted raids across the Dnipro River in the Kherson Oblast, although it did not conduct larger military operation in the region. In addition, Russia and Ukraine were engaged in attacks using missiles, UASs, and special operations forces beyond the front lines in such areas as Crimea.
Southern Front: Beginning in June 2023, Ukraine pursued two main lines of attack on the southern front: one toward the city of Melitopol and other toward the city of Berdiansk. Both cities are transit routes and logistical hubs for Russian forces throughout southern Ukraine and Crimea, the disruption of which represents significant strategic value to Ukraine. However, Ukraine’s progress on the southern front was slow, though deliberate.
Ukraine’s most significant advance was around the town of Robotyne, in the direction of Melitopol. Ukraine advanced a total of roughly 7.6 kilometers from early June to late August 2023—an average of approximately 90 meters per day.[9] This advance was slow even when compared with historical offensives in which the attacker did not draw major benefit from surprise or from air superiority. The Ukrainian offensive did, however, continue to move forward, unlike many historical examples in which the attackers were thrown back.
Ukraine also moved slower than in its previous offensives against Russia, in which it faced less organized defenses. In its 2023 counteroffensive, Ukraine faced a system of fortified defenses—extensively prepared trench lines, minefields, and other fieldworks.[10] During its 2022 counteroffensive in the Kherson Oblast, Ukraine advanced 590 meters a day on average through prepared defenses—systems that include fortifications but that nevertheless were limited by time and resource constraints. Around the same time, Ukraine advanced rapidly in a counteroffensive in the Kharkiv Oblast, moving forward 7.5 kilometers a day on average and overcoming hasty defenses—systems constructed either in contact or when contact is imminent with opposing forces, and that therefore depend on enhancing the natural terrain.
Figure 1 shows the average rate of advance for selected combined arms offensives, such as Galicia, the Somme, Gorzia, and Belleau Wood during World War I; Leningrad and Kursk-Oboyan during World War II; Deversoir (Chinese Farm) during the Yom Kippur War; and Ukraine in 2022 and 2023. Cases were selected from a universe of offensive campaigns lasting more than one day in which the attacker advanced, did not achieve substantial or complete surprise, and did not benefit from air superiority. In addition, cases were selected to ensure variation in geography, technology, time period, attacking and defending forces, and average advance. A much larger number of cases were also consulted, though not included in Figure 1.[11]