With Vladimir Putin engaged in ominous nuclear sabre rattling since the eve of his unprovoked invasion of Ukraine, a vigorous debate has been raging among nuclear experts over whether and when he might make good on his threats. Some argue that the Russian president may consider using tactical, or nonstrategic, nuclear weapons — which are smaller and can be used over shorter distances — to overcome a difficult combat situation or to bring the conflict to an end on terms he considers favourable. Others see potential for him to launch a limited nuclear strike against the United States or a Nato country if they intervene militarily on Kyiv’s behalf.
Although most experts agree that the overall risk of nuclear weapons being used in this conflict remains low, one of these scenarios appears more likely than the other. If Putin’s objective is the occupation of at least some parts of Ukraine, it is hard to see how the use of a nuclear weapon on the country serves his interests. The prospect for a limited nuclear strike against the United States or Nato seems, relatively, greater. Indeed, Putin has promised that anyone who stands in his way will face consequences “such as you have never seen in your entire history”.
It is, therefore, essential to understand the precise red lines the West would need to cross to elicit a nuclear response from Moscow. With few concrete answers available, some analysts have looked to the documents that lay out the circumstances under which Russia says it would or could use nuclear weapons (known as a country’s declaratory policy) for clues.
Moscow’s military doctrine states that Russia “shall reserve the right to use nuclear weapons in response to the use of nuclear and other types of weapons of mass destruction against it and/or its allies”. It also indicates that a nuclear strike could follow “in the event of aggression against the Russian Federation with the use of conventional weapons when the very existence of the state is in jeopardy”. A 2020 presidential decree on the “Foundations of State Policy of the Russian Federation in the Area of Nuclear Deterrence” further indicates that Moscow could use nuclear weapons in response to “reliable data on a launch of ballistic missiles attacking the territory of Russia and/or its allies” or following “the use of nuclear weapons against Russia and/or its allies”. The decree says that Russia could also bring its vast nuclear arsenal to bear after an attack by an adversary “against critical government or military sites of the Russian Federation, disruption of which would undermine nuclear forces response actions”.
On the basis of these documents, some observers are fairly confident that Putin’s menacing rhetoric is unlikely to turn into action. They view him as a rational actor and argue that using nuclear weapons against the West absent an existential threat to Russia would go against its doctrine. Yet this interpretation ignores the fact that these statements refer to a different set of circumstances — namely an attack against Russian territory, rather than preventing outside parties from intervening while it invades another country. Given that Putin’s war on Ukraine falls outside this scope, the nuclear policies are neither especially helpful nor reassuring in this case.
It is more valuable to look at the composition of Russia’s forces overall and the role envisaged for tactical nuclear weapons during a war. Although its conventional capabilities have improved significantly over the last decade, Moscow still relies on its nuclear weapons for flexibility in managing the risk of escalation. Kristin Ven Bruusgaard, a postdoctoral fellow at the University of Oslo who studies Russian nuclear strategy, writes: “The fact that Russia retains a broad range of nonstrategic nuclear capabilities indicates that military and civilian leaders believe such weapons could influence the course of conflict or help terminate it.” However, she concludes that these weapons would only come into play “when Russia had exhausted available conventional escalation tools and was unwilling to back down in the face of existential threat”.
This suggests that Russia would not automatically resort to nuclear weapons to win a conventional war, as some have argued. What is still unclear is at what stage Moscow might deem its conventional tools to have been exhausted, or what Putin himself might consider an existential threat. He has already indicated that he sees US sanctions against his country as “akin to an act of war”. Last week (12 March), Russian officials warned that Moscow would consider convoys carrying Western weapons to Ukraine to be “legitimate targets” for attack.
Without knowing where Putin’s red lines are in this conflict, Western policymakers cannot know how to avoid crossing them. Faced with such perilous ambiguity, the US has so far sought to avoid actions that could give Russia a pretext to escalate the conflict. Joe Biden has consistently rejected requests for direct US military intervention in Ukraine, including a no-fly zone, for instance, which he has claimed could lead to “World War Three”.
Even if the US president maintains his current, prudent course there can be no guarantee that Russia won’t launch a limited nuclear strike anyway. Indeed, as the Stanford University political scientist Scott Sagan has cautioned, Putin’s personalist leadership style means that “external actions” will do little to prevent him from engaging in “reckless nuclear behaviour”. The Russian leader has issued apocalyptic pronouncements in recent years, including about being martyred in a nuclear war. As he is fond of repeating, “even death is beautiful when you are among your people”.
Given the stakes and the rapidly deteriorating relations between Russia and the West, it is vital that policymakers and defence officials on both sides make every effort to communicate with one another in a deliberate and transparent fashion. This will be particularly important as the fighting comes closer to the borders of Nato members such as Poland. While Putin may be confident in his ability to control the course of this conflict through veiled threats and signals, this is a dangerous fantasy. Such an approach could have deadly consequences for everyone.