Ukraine surprised everyone — above all, probably, Vladimir Putin — with its determined resistance to Russia’s attack in February 2022. But now the war has ground down to a lethal stalemate. Ukraine cannot win this war of attrition on its own. Without outside help, a stalemate amounts to an eventual defeat for Ukraine. Reflecting its admiration of the Ukrainians’ courage, as well as the stakes in this conflict, the West has responded with considerable aid. According to the Kiel Institute for the World Economy, the United States has contributed $77 billion in various combinations of military assistance, financial support and...