Ukraine Has a New Military Commander but the Problems Haven’t Changed

Russian forces are razing the already battered city of Avdiivka in eastern Ukraine to the ground and sending waves of assault units to overwhelm outgunned Ukrainian troops. After months of brutal fighting, the Russian military is threatening to cut off a vital supply line to the city, which could render further defense impossible.

As Gen. Oleksandr Syrsky assumes his role as Ukraine’s top military commander — after a broad shake-up of army leadership on Thursday — he could soon be confronted again with the grim calculus that has been a feature of the two-year war: When does the cost of defending ground outweigh any benefit gained by inflicting pain on the enemy?

It is a bloody equation that General Syrsky has had to try to work out many times as the commander of ground forces in eastern Ukraine, and it is one that critics — including American military officials — contend he has not always gotten right, particularly in the battle for Bakhmut.

Assessing that strategy will be only part of the “renewal” that President Volodymyr Zelensky said was necessary when he dismissed his commanding general, Valery Zaluzhny, on Thursday and named General Syrsky to replace him. Mr. Zelensky also named five generals and two colonels he intends to promote as part of the sweeping overhaul.

Ukraine’s military challenges go well beyond any single battle. American assistance, urgently needed, remains in doubt. Ukrainian troops are exhausted, and they lack weapons and ammunition. Air defense systems, crucial to protecting civilians from Russian missiles, are being steadily exhausted by repeated bombardments.