KYIV, Ukraine — Ukrainian officials said on Tuesday that Russia’s Wagner private military company had been forced to shift to using more of its professional soldiers in the battle for Bakhmut as its supply of prisoner recruits dwindled. The claim suggested that Ukraine, by insisting that it will keep defending Bakhmut, may see an opportunity to hang on long enough there to severely damage Wagner, a highly effective fighting force for Russia.
The mercenary force has helped Russia make crawling advances toward Bakhmut largely by throwing waves of ex-prisoners toward Ukrainian positions, wearing Kyiv’s forces down but at heavy cost.
“Almost all of them have been killed there” in Bakhmut, Col. Serhiy Cherevaty, a spokesman for Ukraine’s eastern group of forces, said of the prisoner brigades. The losses among prison recruits have led Wagner to begin deploying more former Russian special forces from within its ranks.
Wagner’s founder, Yevgeny V. Prigozhin, has been in a public battle with Russia’s Defense Ministry and has said that he has not been allowed to recruit more prisoners recently, even though those recruits are thought to have been critical to Wagner’s success in Bakhmut. Mr. Prigozhin — who has criticized Russia’s military leadership as woefully ineffective — has publicly questioned whether that decision to cut off the supply of prisoners is intentional to destroy Wagner’s “offensive potential.”
The comments by Colonel Cherevaty came as some analysts question whether Ukraine should continue to expend so many resources in the withering battle to try to hold on to Bakhmut. On Monday, President Volodymyr Zelensky said that two top Ukrainian military commanders had urged him not to withdraw from the city, even as Russian forces surround the city from three directions and both sides suffer enormous casualties.
Other analysts say that if Ukraine can eliminate Russia’s limited supply of prisoner soldiers in Bakhmut, they will not have to face them again elsewhere.
“Russian convict recruits suitable for combat is not limitless, and the permanent elimination of tens of thousands of them in Bakhmut means that they will not be available for more important fights,” according to the Institute for the Study of War, a research group in Washington.
The group echoed Ukraine’s assessment that Wagner units were shifting away from brigades of former prisoners after enduring steep losses.
“Russian forces near Bakhmut have recently changed tactics and committed higher-quality special forces,” the group said, adding that Wagner was using prisoners there in “a much more limited extent than in previous months” because of high losses in its waves of frontal assaults.
Yet Mr. Prigozhin has justified his group’s brutal tactics in Bakhmut by flipping this logic, highlighting a parallel struggle to shape the legacy of the protracted battle. Mr. Prigozhin and his allies claim that Wagner’s main task in Bakhmut is not territorial gain, but the depletion of experienced Ukrainian units that could have been fighting in other sections of the 600-mile front line.
“The Ukrainian forces send all their combat-ready units to Bakhmut,” Mr. Prigozhin said in late January. Wagner “destroys them, creating operational opportunities in other areas,” he added.
As an example, some pro-war Russian military bloggers — an influential group that closely tracks the war — said the intensification of the Bakhmut battle had coincided with the end of Ukrainian advances in the Kreminna area farther north, where the Kremlin’s forces appear to have regained the initiative in recent weeks. Some Western analysts have made the same point, saying that the fighting in Bakhmut is sapping Ukrainian strength before an expected counteroffensive.
“The tenacious defense of Bakhmut achieved a great deal, expending Russian manpower and ammunition. But strategies can reach points of diminishing returns,” Michael Kofman, a Washington-based expert on the Russian military at the Center for Naval Analyses, wrote on Twitter on Monday after visiting the Bakhmut area. “This fight doesn’t play to Ukraine’s advantages as a force.”
Russia’s defense minister, Sergei K. Shoigu, said on Tuesday that the fight for Bakhmut was “ongoing,” and emphasized its importance for the Russian side. “This city is an important hub for the defense of Ukrainian troops in the Donbas,” he said. “Taking it under control would allow further offensives deep in the defense of the Ukrainian armed forces.”
Anatoly Kurmanaev and Ivan Nechepurenko contributed reporting.