Russian President Vladimir Putin replaced the commander leading his forces in Ukraine just three months after he handed over the job.

General Valery Gerasimov will replace Sergei Surovikin, the country’s Defense Ministry said on Telegram on Wednesday, a change that comes as Kyiv warns Moscow is planning a major new offensive after months of battlefield setbacks.

Surovikin became the first person in sole charge of the campaign in October, and his tenure has been marked by aerial bombardment of Ukraine’s civilian infrastructure as well as Russia’s withdrawal from the crucial southern city of Kherson.

said the ministry he he would now serve as one of Gerasimov’s three deputies, along with Army General Oleg Salyukov and Colonel General Alexey Kim, as part of a new «joint group of forces».

He added that the «increase in the level of leadership» was «related to the expanded range of tasks» and the need for closer cooperation between the branches of Russia’s armed forces.

Rob Lee, a senior fellow at the Institute for Foreign Policy Research, a think tank, said the Twitter that he did not believe Gerasimov’s appointment occurred «because Surovikin is seen as a failure», although he said it was possible that the apparent demotion «was driven by political reasons».

Meanwhile, the Kremlin forces seemed close to a breakthrough in bitter fighting on the eastern front lines.

Battles continued around Soledar, a devastated salt mining town that has witnessed one of the fiercest and costliest recent land battles of the nearly 11-month war.

Ukrainian officials said the country’s soldiers continued to hold out despite heavy fighting and claims that a group of Russian mercenaries had captured the city.

NBC News has not verified the claims by either party.

Taking the city would likely be seen as a significant, if costly, victory for the Kremlin, which has suffered embarrassing defeats on the battlefield and rare signs of unrest at home as the war nears the one-year mark.

The area is in Donetsk province, one of four that Putin claimed to have illegally annexed last year, and is notable for its vast disused mining tunnels.

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