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Competition in Risk-Taking: Russia’s War Against Ukraine and the Risks of Nuclear Escalation1

Like the annexation of Crimea in 2014/15, the Russian war of aggression against Ukraine in 2022 has been accompanied by barely veiled Russian nuclear threats, as a way of demonstrating resolve to the United States and testing reactions in Europe.2 Shortly before launching his war of aggression, Putin ordered a nuclear force exercise to be conducted. As the invasion of Ukraine began, he issued a reminder that Russia remains one of the strongest nuclear powers: “there should be no doubt for anyone that any potential aggressor will face defeat and ominous consequences should it directly attack our country.”3 It was then reported that the “deterrent forces” had been placed on a higher state of alert. Manpower was increased at nuclear command centers. Nuclear submarines set out for exercises in the Barents Sea, and units of the Strategic Rocket Forces in Siberia practiced covert deployment of mobile intercontinental ballistic missile (ICBM) launchers. Apart from that, no further steps were announced or observed – such as loading nuclear weapons onto aircraft, or movements at the sites where shorter-range nuclear weapons are stored. However, like the United States, Russia in any case maintains some of its long-range ballistic missiles at a level of readiness that would allow a rapid response. The threat of a possible nuclear escalation is clearly intended to deter other states from military intervention.4

With his nuclear threats, Putin has introduced an element of strategic unpredictability.5 Moscow’s signals in this regard have potentially turned the war in Ukraine into a nuclear crisis – with the risk of either deliberate or inadvertent escalation, should the crisis between Russia and the West worsen. In such a situation, ambiguous signals may be interpreted in light of the worst-case assumptions, increasing the risk of mutual misperceptions. Concerned about possible misinterpretations, the U.S. Department of Defense canceled a scheduled routine ICBM test-launch.6

Biden’s balancing act – strengthening Ukraine, avoiding war with Russia

President Biden made it clear early on that a direct military conflict between his country and Russia should be avoided at all costs, because that would be “World War III”.7 In the face of uncertainty as to what Russia might regard as interference, the Biden administration’s early line was: yes to supplying arms to Ukraine, to providing some intelligence support to the country, and to comprehensive sanctions; but a strict rejection of Ukraine’s request to enforce a no-fly zone, and avoidance of anything that could be seen as direct involvement in the war. Otherwise, the major concern was that there could be a direct confrontation with Russian forces.8 On the initiative of the United States,  a hotline was established between the U.S. and Russian militaries in order to reduce the danger of an accidental military incident.

It is true that U.S. intelligence agencies expected that Putin would authorize the use of nuclear weapons only in the event of an existential threat to the Russian state or regime. But – they said in May 2022 – in such a tense situation, there is always an increased risk of miscalculations and unintended escalation.9

In any case, from the outset, the Biden administration designed its support for Ukraine with an eye toward a possible horizontal (expansion of the war zone) or vertical (use of nuclear weapons) escalation of the war. The hope was that by incrementally increasing support, and refraining from supplying weapons that Ukraine could use to attack targets deep inside Russia, certain “guardrails” had been set.10

The U.S. administration does not publicly speculate as to what for the Russian leadership would constitute an existential threat to the state or regime that could lead to the use of nuclear weapons. But it clearly does not rule out the possibility that Putin, if faced with a humiliating defeat, might seek to change the dynamics of the conflict by using tactical nuclear weapons – for example, if he had to choose between Russia being forced to withdraw from occupied territories in eastern Ukraine or even losing Crimea, and a nuclear escalation. There are several conceivable possibilities: a demonstrative use in the atmosphere over Ukraine; use against a Ukrainian city to cripple the electricity supply in, say, Kyiv, via the electromagnetic pulse; or use against Ukrainian formations on the battlefield. In his cost/benefit calculation, Putin would have to weigh up whether the possible, but by no means certain, success of nuclear coercion or the military benefits outweighed the reputational costs to Russia of breaking the nuclear taboo – especially among those countries in the global South that have not so far opposed Russia.

The dilemma in which the U.S. administration, indeed the West, would find itself in the event of a Russian use of nuclear weapons, is obvious: on the one hand, Moscow must be denied the benefits it might gain from a nuclear escalation – i.e. no cessation of support for Ukraine, and no pressure on Kyiv to bow to Russian demands. On the other hand, further escalation, possibly leading to war between Russia and NATO, must also be avoided.11

Brinkmanship – politics on the edge of the abyss

Unlike those analysts without political responsibility who speak of an extremely low risk of nuclear escalation, the U.S. administration takes into account the possibility of Putin raising the stakes and confronting the United States with serious and difficult decisions. This is especially the case after Putin, in September 2022, very clearly stated the red line beyond which any means of defense may be used: namely, any threat to Russia’s territorial integrity. By incorporating four regions of Ukraine into Russia, he elevated the war into a defense of Russian territory. Western support for Ukraine thus became aggression directed against Russia, and Putin signalled his readiness to use all means of defense to defend against such aggression. Warning that he was “not bluffing”, he said that the U.S. had created a “precedent” by using nuclear weapons in 1945. Thus he has raised the stakes in the game of nuclear poker. With this and the decision to mobilize, Putin has limited his political room for maneuver in the event of imminent defeat.12

Putin’s policy basically follows the logic of what in classical deterrence theory is called brinkmanship: raising the stakes and being willing to engage in a potentially uncontrollable escalation, in the expectation that the other side will behave rationally and give way.13 The aim is to manipulate the common interest in avoiding a nuclear war, to one’s own advantage. But what happens if the other side also raises the stakes in the “competition in risk-taking”?14 The United States government has repeatedly warned Russia not to use nuclear weapons. In May 2022, President Biden said that any use of nuclear weapons by Russia in the Ukraine war would have “severe consequences”.15 In response to Putin’s rhetorical raising of the stakes, the U.S. administration toughened its tone: now there was talk of “catastrophic consequences” (National Security Adviser Jake Sullivan), and “horrific” consequences (Secretary of State Anthony Blinken).16 It remains unknown what specific warnings the administration may have sent to the Russian government through confidential channels. It is not clear publicly whether the U.S. would respond to a use of Russian nuclear weapons in Ukraine primarily by increasing economic pressure and stepping up military support for Ukraine, or even by launching conventional military attacks on Russian military installations.

The warning of “catastrophic consequences” was accompanied – probably not coincidentally – by a kind of nuclear signaling in the background. This included the deployment of submarines with sea-launched cruise missiles in the European theater. B-52 bombers – albeit not carrying nuclear weapons – are stationed at a base in the United Kingdom. Two took off for flights over Norway to Russia’s northern border; another two approached Russian airspace from the south. In September 2022, the U.S. Strategic Command conducted a ten-day exercise in which the B-52 bomber wing stationed in North Dakota practiced its ability to quickly load nuclear-armed cruise missiles and conduct rapid take-offs.17 In addition, it has been reported that the replacement of nuclear bombs stored in Europe with a newer model (B61-12) is being brought forward to December 2022 from spring 2023. This move is perhaps intended primarily to reassure European allies.18

Escalation risks

With regard to the American reactions, one can speak of a deliberate “strategic ambiguity”. However, by talking about the “catastrophic consequences” that a Russian use of nuclear weapons would entail, the Biden administration may have maneuvered itself into a corner. It has put its own credibility on the line.19 Its response will certainly not be nuclear, because it would make no sense militarily or politically for the Americans to break the nuclear taboo themselves and increase the risk of escalation. But if the U.S. response is a military one, Putin would feel pressure to respond in order to demonstrate his resolve. And in that case, what would Russia’s next step on the escalation ladder be? Conventional attacks against NATO targets? A nuclear attack against NATO ships? Or detonating a nuclear bomb over a military base in Europe to cripple it with the electromagnetic pulse? The Russian leadership seems to believe it holds the better cards in the “competition in risk-taking”, and that the West will not risk a nuclear war for Ukraine.20

The risk of a possibly no longer controllable escalation could already arise if Russia were to take steps in preparation for the use of tactical nuclear bombs. On the Western side, there seems to be no certainty as to whether such preparations would be detected early on – if Russia did not use such preparations as a signal anyway.21 Concrete preparations by Moscow for the use of tactical nuclear weapons could set in motion a process that would heighten the alert on both sides, potentially leading to a nuclear crisis. The Russian leadership cannot be sure how Washington will react to the initial warning signals. Would it expect the United States to put its strategic nuclear forces on heightened alert, and would it proceed to do the same in advance, as a precaution? Or would Moscow opt not to heighten the alert, leave most of its strategic submarines in port, and not deploy mobile missile launchers in the Siberian forests, in order to signal that only a limited nuclear option is being prepared for? Alternatively, if Russia’s strategic submarines leave the ports, American fighter submarines will trail them. Even if Moscow does not prepare its nuclear forces for increased readiness, and Washington also leaves the readiness level of its own nuclear weapons as it is, Western intelligence activities on the Russian periphery would probably intensify – with the possibility that this could lead to entanglements. If it actually came to the use of Russian tactical nuclear weapons, it could presumably be expected that preparations would be initiated on the American side with a view to an escalation – to which, in turn, Russian reactions would have to be expected.22 

The lingering nuclear shadow

The possibility of nuclear escalation casts its shadow over the war in Ukraine. As it seeks to retake occupied territories, the Ukrainian government may be willing to accept the risk of Russia using nuclear weapons. But will the United States accept the risk of an escalating nuclear crisis, or will it urge Ukraine to exercise restraint?23 The U.S. is supporting Ukraine with the goal of strengthening Ukraine’s bargaining position if and when negotiations eventually occur. The U.S. administration has not commented on the conditions under which Kyiv should express openness to negotiations, or on what a negotiated outcome might look like. But there may come a point when the tensions between unconditional support for Ukraine and avoiding an escalation of the war will force the U.S. administration to take a position – and answer the question of whether it would provide Ukraine with military support to take back all its lost territory.24



1 This article is based in part on two earlier publications by the author: Welt im Alarmzustand. Die Wiederkehr nuklearer Abschreckung. Bonn: Verlag J.H.W. Dietz, 2022; Bidens Balanceakt – die Ukraine stärken, Krieg mit Russland verhindern. Berlin: Stiftung Wissenschaft und Politik, June 2022.

2 See Cosgrove, Jonathan (2020): The Russian Invasion of the Crimean Peninsula 2014-2015: A Post-Cold War Nuclear Crisis Case Study. The Johns Hopkins University Applied Physics Laboratory.

3 The speech is documented in translation here: (accessed December 2).

4 See Vern Bruusgaard, Kristin (2022): As Russia struggles in Ukraine, will Putin break the nuclear taboo? In: The Guardian, March 2.

5 See Ziegler, Andrew L. (2022): Strategic Unpredictability: Assessing the Doctrine from Nixon to Putin. In: Survival, 64 (June−July) 3, pp. 49, 66.

6 See Talmadge, Caitlin (2022): The Ukraine crisis is now a nuclear crisis. In: The Washington Post, February 27.

7 Blake, Aaron (2022): Why Biden and the White House keep talking about World War III. In: The Washington Post, March 17.

8 See Toosi, Nahal (2022): White House sweats over its growing entanglement in Ukraine. In: Politico, March 9.

9 Haines, Avril (2022): Annual Threat Assessment of the U.S. Intelligence Community, Opening Statement, Senate Armed Services Committee, May 10. (accessed November 1).

10 See Sanger, David E. et al. (2022): U.S. Is Reluctant As Ukraine Asks To Upgrade Arms, in: The New York Times, September 18.

11 See Betts, Richard K. (2022): Thinking About the Unthinkable in Ukraine: What Happens If Putin Goes Nuclear? In: Foreign Affairs, July 4.

12 See Stanovaya, Tatiana (2022), Putin’s Apocalyptic End Game in Ukraine: Annexation and Mobilization Make Nuclear War More Likely. In: Foreign Affairs, October 6.

13 Traub, James (2022): The Crazy Logic of Brinkmanship Is Back. In: Foreign Policy, September 26.

14 Schelling, Thomas C. (1966): Arms and Influence, New Haven/London, chapter 3.

15 Biden, Joseph R. (2022): What America Will and Will Not Do in Ukraine. In: The New York Times, May 31.

16 See Sanger, David E. and Tankersley, Jim (2022): U.S. Speaks of ‘Catastrophic Consequences’ if Russia Resorts to Nuclear Weapons. In: The New York Times, September 26.

17 See Arkin, William M. (2022): Biden Thinks Non-Nuclear Threats Will Stop Putin. His Military Doesn’t. In: Newsweek, September 29.

18 See Bender, Bryan, McLeary, Paul and Banco, Erin (2022): U.S. speeds up plans to store upgraded nukes in Europe. In: Politico, October 26.

19 Auslin, Michael (2022): The Dangers of ‘Catastrophic Consequences’. In: Foreign Policy, October 21.

20 See Sanger, David E., Troianovski, Anton and Barnes, Julian E. (2022): In Washington, Putin’s Nuclear Threats Stir Growing Alarm. In: The New York Times, October 1.

21 See Bender, Bryan (2022): U.S. steps up intel, surveillance after Putin’s nuke threats. In: Politico, September 27.

22 See Posen, Barry R. (2022): Can Russia and the West Survive a Nuclear Crisis in Ukraine? In: The National Interest, May 13.

23 See Douthat, Ross (2022): A Nuclear Shadow Over the Ukraine War. In: The New York Times, September 25.

24 See Rian, Missy (2022): U.S. expects months of intense fighting in Ukraine-Russia war. In: The Washington Post, September 16.



Peter Rudolf is a Senior Fellow at the German Institute for International and Security Affairs, which he joined in 1988. After studying political science and Catholic theology at the University of Mainz, he received his doctorate degree in political science from the University of Frankfurt am Main in 1989. He worked, among other things, as an APSA (American Political Science Association) Congressional Fellow in Washington, DC and held research posts at Frankfurt Peace Research Institute and the Center for Science and International Affairs, Harvard University.