The difficult decision that Ukraine’s government now faces is between enduring continued bombing by Russia and relinquishing sovereign land to Russia that is a part of its own cultural identity. There are indications that Ukraine may consider ceding territory currently under Russian control if it received ironclad security guarantees in the event of a renewed Russian attack. But Ukraine is still trying to hold onto the part of the Donbas region that it has painstakingly fortified—or, at least, it is trying to avoid recognizing it as Russian and giving it up altogether. Ukraine still holds between 10 to 15 percent...