Russia's “partial mobilization” and its sham referendums to justify the annexation of four provinces in Eastern Ukraine create new sources of uncertainty about the future course of the war. Yet Russia's actions should also produce a rare moment of strategic clarity for Ukraine's partners: No viable path to negotiated peace remains, and any result short of Ukrainian victory will be, in the long run, a worse outcome for the rules-based international order. The third, and more politically significant, alternative falls somewhere between the first two. This camp decries Russia's barbarity and lauds Ukrainians' bravery while, at same time, worrying about...