Recent Ukrainian advances in western Zaporizhzhia Oblast and south of Bakhmut correspond with evidence that Russian units in those areas have suffered heavy losses, the Institute for the Study of War (ISW) wrote in its Sept. 18 report.
The ISW identified a number of Russian front-line units, including the 42nd Motorized Rifle Division, that regularly fought Ukrainian troops during the earlier stages of the counteroffensive.
Following recent Ukrainian advances, these units appear to have withdrawn.
"The absence of recent reports and footage of these elements participating in combat engagements in western Zaporizhia Oblast suggests that casualties sustained during the first phases of the Ukrainian counteroffensive rendered them combat ineffective," the ISW said.
The ISW also said that elements of Russia's Black Sea Fleet appear to have retreated behind deeper defensive lines following Ukraine's liberation of Robotyne.
Further, the ISW said that elite Russian units dedicated to counterattacking advancing Ukrainian troops have "likely suffered heavy losses in these operations."
Russian units south of Bakhmut have also racked up heavy losses. The ISW said that Russia's 72nd Motorized Brigade "has likely been rendered combat ineffective."
The ISW's report cautioned that it is too soon to tell exactly what level of degradation Russian units in western Zaporizhzhia and the Bakhmut sector have suffered, and that losses may vary across units.
However, the ISW said that "evidence currently available" points to heavy losses, including loss of combat effectiveness among elite Russian units.