Who is Winning the Russo-Ukrainian War?

What’s happening in the nearly six-month-old Russo-Ukrainian war? It’s hard to say. Moscow expected a proverbial cakewalk and bungled its initial attack. After rebuffing Russia’s assault, the Zelensky government expanded its objectives, expressing its desire to reconquer portions of the Donbas seized by separatists with Russian support in 2014, as well as Crimea, which had been formally annexed by Moscow.

In recent months, however, Russian forces have made slow progress in the Donbas and now occupy a fifth or more of Ukrainian territory. But Ukraine and its advocates have been...