Ukraine and the West will have to create military realities that permit a cessation of hostilities on terms that they can effectively impose on Putin in that case. 

Ukrainian forces, properly supported by the collective West, can retake the terrain that is strategically vital to Ukraine’s military and economic survival and that would be essential for renewed Russian offensives on terms favorable to Moscow. ISW has assessed the operational and strategic significance of various parts of occupied Ukrainian territory and stands by that assessment. There likely is a line short of the full restoration of Ukrainian control over all of occupied Ukrainian territory that could be the basis for a protracted cessation of hostilities on terms acceptable to Ukraine and the West—but that line is not close to where the current front lines stand.

It is not a given, nevertheless, that Putin will continue fighting regardless of cost until the day he dies. 

He has ostentatiously and surprisingly refrained from going all-in on this war from its inception. One can dismiss his failure fully to mobilize and prepare his military before the invasion because he clearly believed that the Ukrainians would not or could not fight. He has passed by multiple moments when moving to fuller mobilization had become necessary, has delayed decisions to implement even partial mobilization for far too long from Russia’s perspective, and even when he has made such decisions has sought to limit their impact on the Russian society and economy. Putin’s Stalinist rhetoric aside, he has shown remarkable concern about the danger of pushing Russia too far and generating a threat to the stability of his regime. Ukraine and the West should not count on Putin’s will breaking by any means, but neither should they dismiss the possibility that he might at some point decide that the costs and risks of continuing the fight are no longer justified by the potential gains.

Putin is nevertheless putting no terms for negotiation on the table now other than Russia’s total success. He is not taking the military measures that would be prudent were he serious about seeking some negotiated off-ramp or compromise settlement. The current frontlines would set highly favorable conditions for renewed Russian invasions if Putin were offering to accept them as a ceasefire boundary—but he clearly is unwilling to do so.