Armored vehicles remain the best method of rapidly exploiting a breach in enemy defenses. That Russia can’t deploy them for their intended purpose means that, barring a total collapse in Ukrainian defenses, the Kremlin has no way of breaking through. Instead, Russian forces can only creep forward with frequent small infantry attacks, advancing a kilometer at a time.

Infantry-first assaults are costly—415,000 Russians were killed or wounded last year, according to the Institute for the Study of War in Washington, D.C. But manpower remains cheap and abundant in Russia; armored vehicles aren’t.