"Slovyansk is Russia's core ambition"
Russian troops are preparing an offensive against the eastern city of Slovyansk in an effort to push east and link up with other forces in the Donbas region, according to the latest assessment from the Institute for the Study of War think tank.
"Efforts by Russian forces advancing from Izyum to capture Slovyansk will likely prove to be the next pivotal battle of the war in Ukraine," the report says.
The Russians must take "Slovyansk as their minimum step".
If they are unable to do so, their effort to capture the eastern Donetsk and Luhansk regions "will likely fail". Russian forces continue to make little to no progress in assaults in those areas, says the think tank.
Ukraine's troops also continue to hold Mariupol and are likely to inflict heavy casualties on the Russians.
"Russian efforts to generate replacements from reservists and feed damaged units from north-eastern Ukraine into frontal assaults in eastern Ukraine are unlikely to increase their chances of success," the report adds.
Russian troops have departed the Chernihiv and Sumy regions in the north, and "will likely completely vacate these regions in the coming days".