Table of Contents Introduction The Offense-Defense Balance How Are Russia’s Defenses Organized? What Obstacles Could a Ukrainian Offensive Face? Lessons for Ukraine: Shifting the Advantage to the Offense Next Steps: Chapter One- The Offense-Defense Balance
The Offense-Defense Balance The offense-defense balance is the relative strength between the offense and the defense in warfare. The core idea behind the offense-defense balance is that there are several factors, such as technology and geography, that can influence the relative benefits and costs of attacking versus defending.[2] These factors impact whether the offense or defense has the advantage.[3] As political scientist Robert Jervis wrote in one of the most influential works on the topic: “When we say that the offense has the advantage, we simply mean that it is easier to destroy the other’s army and take its territory than it is to defend one’s own. When the defense has the advantage, it is easier to protect and to hold than it is to move forward, destroy, and take.”[4] The offense has the advantage if the expected benefits of attacking outweigh its costs by more than the expected benefits of defending outweigh its costs.
Several factors relevant to the current war in Ukraine impact the offense-defense balance. The first is technology. Innovations that can help a military to conduct maneuver warfare and swiftly advance into enemy-controlled territory may favor the offense. For example, advances in military mobility—such as tanks, fighter aircraft, chariots, horse cavalry, or even earlier critical components (such as the stirrup)—have sometimes favored the offense.[5] These technologies—and how militaries employ them—have increased the possibility that forces can punch through opponents’ lines and exploit their breakthroughs.
Conversely, advances that decrease mobility—such as moats, land mines, trenches, and barbed wire—have sometimes favored the defense. Firepower such as machine guns, fast-firing rifles, infantry anti-tank weapons, and air defense systems have also favored the defense.[6] The high lethality of these weapons increases the need for cover and concealment, allowing the defender to fight from prepared positions while the attacker must advance over relatively open ground.
A second factor that impacts the offense-defense balance is geography. Terrain that includes flat plains, open fields, and deserts can favor the offense because these features offer good visibility, ample room for maneuver, and fewer natural obstacles. Open terrain generally allows for easier mobility, flanking maneuvers, and the potential to rapidly concentrate forces at critical points.
Terrain that slows movement or makes it difficult to provide logistics—such as thick forests, dense jungles, swamps, mountainous terrain with few passes, and rivers and other bodies of water with few or no bridges—often strengthens the defense. Such geographic barriers can force attacks into the few roads, bridges, or passes that are available, thus reducing the defender’s intelligence difficulties as well as shortening the length of the front requiring defense. During the Cold War, for instance, the North Atlantic Treaty Organization’s plans for defending West Germany focused on the North German plain and the Fulda Gap, a pair of lowland corridors near the border between East and West Germany, because these were two places where major mechanized offensives against West Germany seemed feasible.
Distance also often favors the defense. If the attacker must travel a considerable distance just to reach the defender’s territory, the amount of force it can project is reduced by the costs of transporting and supplying the projected force, as well as the costs of defending long lines of communication.[8] In addition, the offense-defense balance depends, in part, on how much territory the attacker is trying to take. More ambitious offensive missions, including those designed to take more territory, tend to be more difficult than less ambitious ones.
Weather can further impact the offense-defense balance.[10] In cold weather climates, frozen ground can support the offensive movement of mechanized forces in winter. As the Soviet army discovered during its invasion of Finland in November 1939, however, winter fighting can also mean operating in conditions of biting cold and deep snow. In the spring in some parts of the world, including Ukraine, mechanized forces have to deal with the Rasputitsa, or thaw, during which the ground turns to mud and the advantage may shift to the defense. During the summer in Ukraine, however, the steppes dry out and allow for better movement of tracked and wheeled vehicles.
There are other factors that can impact the offense-defense balance, such as clever strategies, force employment, leadership, and combat motivation.[11] Today, the challenge for the Ukrainian military and its Western supporters is to leverage technology, geography, strategy, force employment, leadership, combat motivation, and other factors to increase the relative benefits and reduce the costs of offensive operations. Conversely, the task for Russia is to build strong enough defenses (such as trenches and berms), layer these defenses with sufficient weapons systems (such as surface-to-air missiles and artillery), and utilize favorable terrain to blunt successful Ukrainian counterattacks. Chapter Two to be published tomorrow: How Are Russia’s Defenses Organized?
