The conflict could still take an unexpected turn, as it has before. But the prospect at this juncture is of a long war of attrition, inflicting ever more damage on Ukraine, sacrificing ever more lives and spreading instability over Europe. The way things are going, “Ukraine will for the foreseeable future harbor Europe’s most dangerous geopolitical fault line,” argues Michael Kimmage, author of “Collisions,” a new history of the war. He foresees an endless conflict that would deepen Russia’s alienation from the West, enshrine Putinism and delay Ukraine’s integration into Europe.

That, at least, is the bleak prognosis if victory in the war continues to be defined in territorial terms, specifically the goal of driving Russia out of all the Ukrainian lands it occupied in 2014 and over the past 22 months, including Crimea and a thick wedge of southeastern Ukraine, altogether about a fifth of Ukraine’s sovereign territory.

But regaining territory is the wrong way to imagine the best outcome. True victory for Ukraine is to rise from the hell of the war as a strong, independent, prosperous and secure state, firmly planted in the West. It would be exactly what Mr. Putin most feared from a neighboring state with deep historical ties to Russia, and would be a testament to what Russia promised to become in 1991, when both countries broke free of the Soviet Union, before Mr. Putin entered the Kremlin and succumbed to grievance and the lure of dictatorial power and imperial illusion.

Any talk of armistice is understandably difficult for Volodymyr Zelensky, the intrepid Ukrainian president who has steadfastly sought to project a morale bolstering picture of steady battlefield successes. It would be very painful, and politically very difficult, for him to halt the fighting without punishing Russia and leaving it in control of so much Ukrainian land. After his senior military commander, Gen. Valery Zaluzhny, described the true state of affairs as a stalemate in an interview with The Economist in November, Mr. Zelensky bristled at what he perceived as defeatism.

But to explore an armistice is not to walk away. On the contrary, the fight must go on, even when talks begin, to maintain the military and economic pressure on Russia. Those people who are resisting continued aid to Ukraine, whether some Republicans in Congress or Viktor Orban in Hungary, must not be allowed to abandon the Ukrainians at this juncture. If Mr. Putin is seriously looking for a cease-fire, he is doing so on the presumption that the alternative is a continued slaughter of his soldiers, and that there is nothing more he can achieve through destruction, violence or bluster.