Poster Comment:
The Ukrainians have lost over 600,000 dead and almost as many permanently disabled. They have key battle points but Russia has superior weapons and greater numbers of soldiers so they can challenge the Ukrainians at many more points. This allows to Russians to surround the enemy, cut off supplies and reinforcements. Then they can fire from several different directions simultaneously.
Pokrovsk is a rail center. It distributes supplies to the Donbass. When it falls and the Russians cross the nearby Dnieper river, there will be no more fortified positions where the Russians have to dig them out.