It took Russia weeks of fierce fighting, an untold number of casualties, and relentless shelling before the exhausted Ukrainian defenders of Sievierodonetsk received orders to quit its smouldering wreckage.

"Remaining in positions smashed to pieces over many months just for the sake of staying there does not make sense," Serhiy Gaidai, governor of the wider region, said on Ukrainian television on Friday.

With a reported 90% of the industrial city's buildings damaged, most of its around 100,000 residents long gone, and with limited strategic value beyond a sprawling chemical plant, it does not look like much of a prize.