The Impact of the Kakhovka Dam Breach on the New Ukrainian Counteroffensive

On June 6, the Kakhovka Dam on the Dnipro River was breached, releasing a flood of water from Ukraine’s largest reservoir downriver toward the city of Kherson. In addition to severe humanitarian and environmental concerns, the destruction of the dam has implications for Ukraine’s freshly launched counteroffensive. The dam’s breach will not be sufficient to stop a Ukrainian offensive across the Dnipro River in Kherson Oblast this summer, but it will delay such an operation by at least several weeks. Such a delay shifts advantages to the Russian defenders in the neighboring Zaporizhzhia Oblast and complicates the already difficult task that lays before Ukraine to dislodge Russian forces from heavily fortified positions across the front.

Ukrainian operations are ongoing in several areas across the front, with reports of fierce fighting near the border between Zaporizhzhia and Donetsk Oblasts. Although it is too soon to accurately assess the overall course of the offensive, it is clear that Ukraine has not yet achieved the same operational surprise that allowed it to quickly retake the majority of Kharkiv Oblast in the fall of 2022.

Few observers expected Ukraine to replicate its blitz across Kharkiv. In anticipation of Ukrainian attacks, Russia prepared the most extensive fortifications in Europe since World War II across the territory it holds in Ukraine. In Kherson Oblast, Russian forces have relied on the Dnipro River to serve as their first line of defense. The breach of the Kakhovka Dam further enhances Russia’s defensive positions and disrupts whatever planning was ongoing for a Ukrainian offensive in Kherson Oblast.

Riley McCabe
Program Manager and Research Associate, Transnational Threats Project
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An assault across the Dnipro River holds the prospect of significant benefits for Ukraine. An offensive in Kherson Oblast would provide Ukrainian forces with the shortest possible land route to the Crimean Peninsula, the liberation of which is one of Ukraine’s stated strategic goals for the war. Kherson Oblast is also fortified relatively sparsely compared to the neighboring Zaporizhzhia Oblast, meaning that maneuver forces would face fewer layers of entrenched defenders in the case of a breakthrough.

The destruction of the road across the Kakhovka Dam and existing damage to the Antonovsky Bridge—the only two road bridges across the Dnipro River in Kherson Oblast—means a river-crossing operation remains Ukraine’s only option for an offensive originating in Kherson Oblast. The flooding, however, will impact several variables that influence the feasibility and success of such an operation.

Damage to Antonovsky Bridge in Kherson Oblast

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As a result of the flooding, the river grew wider, deeper, and faster downstream from the dam. The expanded width will require more assets to cross via bridging and expose crossing forces to potential enemy fire for longer periods of time, while the greater depth and speed of the water complicates crossing techniques. For example, near the town of Korsunka—an area that Russia had fortified prior to the breach—the width of the river expanded from 583 meters to 3,660 meters across at one section, shown below. The size and flow of the river will also continue to change as flood waters recede, altering the requirements for a crossing on a daily basis.

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The flooding has also changed the conditions of the geography around the river. Floodwaters have moved the riverbanks into new areas, including in nearby towns and fields. Previously suitable staging, call forward, and bridgehead areas are also likely flooded and unusable. Even as the flood waters recede, the riverbanks will remain altered and nearby areas will be waterlogged, limiting the mobility of troops and equipment. Obstacles, including trees, infrastructure, and potentially even landmines, have also been uprooted and moved to unexpected locations. The result is that a new round of reconnaissance will be required before any attempt to assault across the river.

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Another key constraint on a Ukrainian offensive across the Dnipro River in Kherson Oblast is the logistics operations that would have to follow to support a large and sustained offensive. Forces can only fight if they are supplied, and Ukraine would have to regularly cross the river to deliver ammunition, fuel, vehicle parts, and reinforcements to its units on the far bank. Without such supply lines, any forces committed would risk being isolated in a Russian counterattack or be unable to exploit the success of an initial assault.

The width of the Dnipro River and lack of existing bridges means that Ukrainian logistics and follow-on forces would need to establish new bridging, rely on ferries, or a combination of both. During its 2022 withdrawal from the city of Kherson, Russia used ferries to move troops and equipment across the river, as shown below. Ukraine presumably refrained from targeting Russia’s ferry operation because it wanted the Russians out of the city. Today, however, Russia would attempt to strike the vulnerable dock and loading areas if Ukraine were to fail to first push back enemy indirect fires. Any bridging operation across the river would need to account for the same threat of indirect fires.

Ferry Operations during Russia’s Withdrawal from Kherson in October 2022

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By delaying a potential offensive in Kherson Oblast, the dam’s breach increases pressure on ongoing offensive operations elsewhere along the front. Russia is already reportedly redeploying units from the south to reinforce defensive positions further north. These redeployments will increase the number of Russian troops available to defend against Ukrainian attacks and may free operational reserves to contain Ukrainian breakthroughs or conduct counterattacks.

Even still, a Ukrainian offensive across the Dnipro River remains possible in the coming months. Common knowledge of an operation’s difficulty can work in the attacker’s favor by generating operational surprise. The landing at Inchon in 1950 during the Korean War was initially dismissed by both UN and North Korean forces as too difficult, but the amphibious assault by UN forces against underdefended enemy positions took and created the conditions the near-total collapse of the In Min Gun within a month.

A successful crossing of the Dnipro River near Kherson is extremely unlikely to have such a dramatic strategic effect, but it could catch Russian forces off guard and allow Ukraine to bypass the defensive systems Russia has constructed further north and strike important groundlines of communication leading from Crimea.

For now, however, a Ukrainian offensive in Kherson Oblast is extremely unlikely to be viable for at least several weeks because the reconnaissance and planning that determines the success of any major river-crossing operation will need to begin again. In the meantime, Russia will continue to capitalize on the defensive advantages it gained from the breach.

Riley McCabe is a program coordinator and research assistant with the Transnational Threats Project at the Center for Strategic and International Studies (CSIS) in Washington, D.C. Alexander Palmer is a research associate with the Transnational Threats Project at CSIS. Joseph S. Bermudez Jr. is senior fellow for imagery analysis with the iDeas Lab and Korea Chair at CSIS.