it's not a good comparison because of the power ratio of russia and the us. this is relevant because of considerations of costs and benefits of either choice. i think you are only considering the benefits of continuing to fight and the costs of giving up. what you should do is consider the costs and benefits of both options individually. you mention the amount of land. keeping it is a benefit continuing to fight. however, the cost of that choice has to be considered too. will it be 100,000 men? 500,000? 5 million? all? is there a number of men where their value is equivalent to the value of the land, so that losing more men than that would not be worth getting the land back? also, it must be considered that no number of men will get the land back. every ukrainian could be killed, and the land might still be lost. so in your equation, you would need to add a probabilistic term, which would reduce the number of men you are willing to spend to get the land back.
United States