Seizing the Initiative in Ukraine: Waging War in a Defense Dominant World

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.