What is not often said is that nuclear deterrence is working and, as a result, both the United States and Russia face constraints in how they approach conflict that involves the other. Nuclear deterrence has limited the escalation of the conflict in profound ways, despite brutal fighting, heavy casualties, and the supply of substantial amounts of Western weaponry to Ukraine. This is welcome news, but there is a caution: There is no guarantee that it will continue to do so, nor can there be. The management of escalation means that the United States and NATO will have to accept that it too faces limits in how to approach the conflict. It would be unwise to hand-wave away Russian nuclear threats, or to dismiss as so many have the Russian threat to use nuclear weapons, based on a warped understanding deterrence theory.