KYIV, Ukraine — Russia’s Defense Ministry claimed on Friday that its forces had captured the coal mining town of Toretsk in their latest breakthrough in eastern Ukraine’s Donetsk region, where Ukrainian defenses are creaking.

Ukrainian officials did not immediately make any comments on the Russian claim.

A Ukrainian officer in a brigade on the outskirts of Toretsk cast doubt on the Russian statement. Yevhen Alkhimov, the press officer of the 28th Brigade, told The Associated Press by phone that his unit had not been moved from its position, which he said likely would have happened if Toretsk had fallen.

Russia’s much larger army has conducted a sustained yearlong campaign along the eastern front, gradually loosening the short-handed and weary Ukrainian forces’ grip on its strongholds as the war approaches its fourth year later this month.

The losses coincide with uncertainty over whether the United States will keep providing vital military aid. U.S. President Donald Trump, who says he is making American interests his priority, has said he wants to end the war, although his plans for securing peace are unclear.

Alkhimov, the 28th Brigade officer, told AP his unit continued to hold its ground on Friday afternoon. He added: “Intense (Russian) assault operations are ongoing.”

DeepState, an open-source Ukrainian map widely used by the military and analysts, showed late Thursday that Ukrainian troops were on the northwest edge of Toretsk and still had some soldiers inside the town itself.

Russian Claims and Ukrainian Fortifications

The Russian Defense Ministry said the Ukrainian military has heavily fortified Toretsk and developed a network of underground communications, turning practically every building into a well-protected firing position. The Ukrainian forces also have used coal mines and waste heaps in Toretsk’s western and northern parts as defenses, it said in a statement.

Russia’s claimed fall of Toretsk, if confirmed, would advance its sweep across the Donetsk, which has cost Moscow heavily in troops and armor but has paid dividends for the Kremlin. In the offensive, Russian forces crush settlements with the brute force of 3,000-pound (1,300-kilo) glide bombs, artillery, missiles and drones, then send in infantry units to attack the exposed defenders.

Recent Russian Advances in Eastern Ukraine

So far this year, Kurakhove was the first significant town to capitulate under Russia’s onslaught, after Russian forces captured Avdiivka and Vuhledar last year. Russian forces last month also took Velyka Novosilka, in the same area.

The towns were part of a belt of Ukrainian defenses in the east. Russia’s other targets are the key logistics hub of Pokrovsk and the strategically important city of Chasiv Yar.

Russia seeks to take control of all parts of Donetsk and neighboring Luhansk, which together make up Ukraine’s Donbas industrial region.

Russia accelerated its destruction of Ukraine’s front-line cities in 2024 to a scale previously unseen in the war, using the glide bombs and an expanding network of airstrips, according to an Associated Press analysis last year of drone footage, satellite imagery, Ukrainian documents and Russian photos.

UN Atomic Watchdog Discusses Nuclear Plant Security

Meanwhile, the head of the U.N. atomic watchdog met Friday in Moscow with the chief of Russia’s state-owned nuclear energy provider Rosatom to discuss security around southern Ukraine’s Zaporizhzhia Nuclear Power Plant.

International Atomic Energy Agency chief Rafael Grossi said the situation around Europe’s biggest nuclear plant was “unprecedented” because it is “in the middle of an active combat zone.”

In Kyiv on Tuesday, Grossi said there were “a few occasions where we had close calls ” with regard to the plant, which is under Russian occupation.