The Russo-Ukrainian War and the Durability of Deterrence

Abstract Both the Russian Federation and the United States and its allies have avoided taking actions carrying the greatest risk of escalation to nuclear-weapons use. Left uncertain is whether specific contingencies might yet prompt nuclear use. But the Russo-Ukrainian war has now been going on long enough to ground the debate in what has been said and done during its course. Russian nuclear decision-making requires the most attention, and Russian President Vladimir Putin’s statements about it have been the most authoritative. He has defined Russia’s nuclear red line consistently and relatively restrictively, reserving the threat of nuclear use for an existential threat to the state. He has focused on deterring the West from fighting alongside Ukraine, disregarding those who wanted to punish the West for the support it was providing. So long as NATO continues to respect Putin’s red line, there is no reason to believe Putin would authorise nuclear use.