Ukraine's gains in south undermine Russia's plans in Donetsk region — ISW

Ukrainian military advances in south

According to analysts, the Ukrainian military has achieved significant tactical gains in the south since late January 2026.

According to the Ukrainian Air Assault Forces, as of March 26, the town of Berezove had been liberated, which allowed for the elimination of the Russian salient in that direction.

The report notes that since late January 2026, Ukrainian forces have recaptured more territory than Russian forces seized in February 2026.

Ukraine states that in the Oleksandrivka and Huliaipole sectors, over 400 square kilometers have been liberated from the occupiers since late January, as part of two separate operations.

The ISW currently has evidence of the liberation of at least 334.06 square kilometers in southern Ukraine, though analysts acknowledge that the ISW’s conservative mapping methodology underestimates Ukrainian gains.

Russia forced to change its plans

"Ukrainian forces’ dual tactical efforts to halt and push back Russian gains in southern Ukraine are having cascading effects on other sectors of the front, forcing Russian forces to choose between defending against the Ukrainian counterattacks and allocating manpower and materiel for offensive operations elsewhere on the frontline," the ISW believes.

As a result, in early March, the Russian command was forced to redeploy elite units, paratroopers, and marines from the Donetsk region to southern Ukraine, which likely derailed plans for the spring-summer 2026 offensive against the Fortress Belt.

Fortress Belt

Experts believe that the Russians are unlikely to capture Ukraine's Fortress Belt in 2026.

The Russians launched their spring-summer offensive against the well-fortified cities of the Donetsk region with a significant increase in mechanized and motorized assaults across various sections of the front between March 17 and 21, as well as a period of intensified strikes and the movement of heavy equipment and troops to the front lines.

They clarified that the Fortress Belt refers to a cluster of four heavily fortified and large cities in the Donetsk region with a combined pre-war population of over 380,000 people, stretching from north to south along the H-20 Kostiantynivka-Sloviansk highway.

The ISW notes that the Russians had already attempted to capture the Fortress Belt in 2014 and 2022 but failed, and such an operation in the fifth year of the war would likely be a multi-year effort involving significant losses of personnel and equipment.

Problems in Russia

At the same time, even within Russia itself, problems are acknowledged. In particular, Andrei Kartapolov, chairman of the State Duma’s Defense Committee, stated that it is currently too early to speak of a triumphant spring offensive.

The ISW adds that the Kremlin is aware of the difficulty of capturing these territories and is therefore trying to pressure Ukraine into making concessions to avoid significant losses and conserve resources for future operations.

Situation on front

Russian troops have intensified offensive operations in certain sectors of the front in recent weeks.

According to the ISW, Russian troops have likely already launched a spring-summer offensive against Ukraine’s Fortress Belt in the Donetsk region.

The main pressure is concentrated on the Lyman sector, which opens the way to Sloviansk and Kramatorsk.

At the same time, the Ukrainian Defense Forces are demonstrating success. In particular, it has been reported that control has been established over the settlement of Berezove in the Dnipropetrovsk region.

In addition, during a counteroffensive in the Oleksandrivka direction, Ukrainian troops liberated 9 settlements and completely cleared 3 more of Russian forces.