Russian forces have razed dozens of towns and cities in Ukraine over the past 26 months — killing thousands of civilians, forcing millions from their homes and leaving a trail of destruction that is impossible to calculate.

Sievierodonetsk. Bakhmut. Avdiivka. Cities and towns little known to the world have become the scorched-earth battlegrounds where two armies clashed for months to bloody effect before the Russians finally prevailed.

Now Russian forces have set their sight on Chasiv Yar, a hilltop fortress town in eastern Ukraine. The campaign is part of an intense effort by Russia to achieve what could be its most operationally significant advance since the first summer of the war in 2022.

Chasiv Yar covers only about five square miles, but if the Russians can seize it they will control commanding heights that will allow them to directly target the main agglomeration of cities still under Kyiv’s control in the Donetsk region. That includes the headquarters of the Ukrainian eastern command in Kramatorsk.

It would also put Russian troops within around 10 miles of Kostiantynivka, the main supply juncture for Ukrainian forces across much of the eastern front.

Chasiv Yar is the “key” that “will open the gate for exhaustive and long-lasting battles,” said Serhiy Hrabsky, a military analyst who is a former colonel in the Ukrainian Army.