The Ukraine war: Nuclear risks and consequences

  • Bruno Tertrais
    Deputy Director of the Foundation for Strategic Research (FRS), France
Foreign Policy & International Relations

The Ukraine war: Nuclear risks and consequences


The risk of Russia resorting to nuclear weapons in the Ukraine war is overestimated. There is no evidence that Moscow is considering such use. Official Russian statements have remained entirely consistent with the Russian state doctrine. No worrying nuclear weapons movements have been detected and, contrary to popular perception, Russia’s nuclear force has not been put on high alert. Overall, nuclear weapons are so far playing the same role as they did during the Cold war: they limit the scope of confrontation between nuclear-armed countries. However, the Ukraine war may herald a new era of nuclear dangers. The narrative according to which “once again, a country that gave up nuclear weapons has been attacked” will gain credibility. Western allies may seek additional nuclear protection through nuclear sharing and stationing. And if Russia emerges seriously weakened by the war, it may once again be tempted to rely on nuclear weapons to compensate for perceived conventional force shortcomings.

The shadow of nuclear weapons over the war in Ukraine

The Russian war against Ukraine is in many ways a conflict in a nuclear atmosphere. The possession of nuclear weapons allows Moscow to conduct major offensive operations. President Putin mentioned Ukraine's alleged interest in nuclear weapons in his February 24 speech announcing the start of the war.[1] The Belarusian constitutional referendum (February 27) permits the deployment of Russian nuclear weapons on the territory. And, of course, there have been multiple explicit and implicit references to Russia's nuclear deterrent and force posture.

But the risk of Russia resorting to nuclear weapons in the Ukraine war – a fear expressed by US public opinion in particular, as well as by some experts – is overestimated.[2] There is no evidence that Moscow is considering such use. Official Russian statements have remained consistent with the Russian state doctrine. No worrying nuclear weapons movements have been detected and, contrary to popular perception, Russia’s nuclear force has not been put on high alert. Overall, nuclear weapons are so far playing the same role as they did during the Cold war: they limit the scope of confrontation between nuclear-armed countries. However, the Ukraine war may herald a new era of nuclear dangers. The narrative according to which “once again, a country that gave up nuclear weapons has been attacked” will gain credibility. Western allies may seek additional nuclear protection through nuclear sharing and stationing. And if Russia emerges seriously weakened by the war, it may once again be tempted to rely on nuclear weapons to compensate for perceived conventional force shortcomings.

The deterrence game in the Ukrainian crisis

Russia has benefitted from what the French call “aggressive sanctuarization”: since it feels sheltered by its nuclear arsenal, it can afford to embark in significant military operations against  its neighborhood. But Russian armed forces are not striking bases on NATO territory (and no use of chemical weapons has been detected). For its part, NATO does not engage directly with Russia and has failed to establish any “no-fly zone” over Ukraine for fear of striking Russian aircraft. This situation is reminiscent of the open crises of the Cold War – Korea, Vietnam, the Middle East. Thus, it can be said that the war in Ukraine confirms that nuclear deterrence allows for military engagement while limiting the risks of escalation.[3]

Indeed, there has been nuclear restraint on both sides. On the Russian side, the thesis according to which Moscow is quick to brandish the nuclear threat is questionable. One cannot fail to be struck by the contrast between the warlike violence of the Russian army and the policy of deterrence of the Kremlin during the crisis. While Russian commentators have made provocative, and frequently inflammatory, statements, policymakers have mostly confined themselves to “deterrence reminders” or the extent of Russian capabilities: they convey the message that Russia would resort to nuclear weapons if it were to be attacked, but are not threats per se. Mr. Putin, in his speech on February 24, said: “No matter who tries to stand in our way or all the more so create threats for our country and our people, they must know that Russia will respond immediately, and the consequences will be such as you have never seen in your entire history. No matter how the events unfold, we are ready. All the necessary decisions in this regard have been taken. I hope that my words will be heard.”[4] The Kremlin spokesman confirmed on March 22 that Russia would only use nuclear weapons in case of an “existential threat” to the country.[5] He later said that “no one was thinking about the use – or even the idea of using a nuclear weapon.”[6] That same week, the Deputy Chairman of the National Security Council, Dmitry Medvedev, recalled the four thresholds of Russian vital interests (explained further below).[7] In an interview on April 19, Minister of Foreign Affairs of the Russian Federation, Sergei Lavrov, ruled out the possibility of using nuclear weapons.[8] In another interview, he said that Russia was doing everything to avoid a nuclear war.[9] On April 20, on the occasion of a Sarmat missile test, Putin said that the missile was intended to “make those who, in the heat of aggressive rhetoric, try to threaten our country, think twice.”[10] And on April 29, he stated: “If anyone intends to intervene from the outside and create a strategic threat to Russia that is unacceptable to us, they should know that our retaliatory strikes will be lightning-fast.”[11]

On the whole, it can be said that Russia has been careful not to appear to have its “finger on the button” and even more careful not to implement what Richard Nixon called the “madman theory” (cf. the US alert of 1969), which consists of feigning irrationality in order to better frighten the opponent.[12]

There has been no obvious change in the posture of the Russian nuclear forces. The much-publicized decision of 27 February consisted simply of an increase in the permanent presence of personnel in the strategic forces' headquarters and not of an increase in alert levels.[13] As U.S. National Security Advisor Jake Sullivan pointed out in March: “We haven’t seen anything that’s made us adjust our [nuclear] posture.”[14] U.S. officials went further, suggesting that they had not detected any movement of weapons to the West or any relaxation of controls on the Russian arsenal.[15] This allowed U.S. President Biden to state that they “currently see no indication that Russia has intent to use nuclear weapons in Ukraine.”[16]

Moscow conducted a Grom exercise in February 2022, a large-scale maneuver involving the entire triad. However, it should be remembered that this exercise involved the strategic deterrent as a whole (including non-nuclear assets), which was reminiscent of the American Global Thunder exercises, from which they seem to have borrowed their name.[17] The test of a Sarmat missile on April 20 was apparently part of the normal missile validation schedule. There was also an overflight of Moscow on May 4 by an Ilyushin-80 Maxdome, which had not been seen since 2010, and on May 5 an exercise involving Iskander missiles in Kaliningrad, although it is not clear that it involved a nuclear dimension of the latter.[18] However, the number and magnitude of nuclear signals sent by Russia remained limited.

How can one explain this discrepancy between the inflammatory declarations of the media and the relative public serenity of the Russian authorities (which could be the result of role-sharing as the Kremlin wishes to appear “reasonable”)?[19] Firstly, by the coherence between the situation in the Ukrainian theater and the Russian nuclear doctrine. Since Russia's most essential interests are not at stake, Moscow would have limited itself to dissuading Western countries from getting directly involved in the conflict.[20] It has been pointed out that the case of a “special operation” is not covered by the Russian doctrine.[21] But also, perhaps, by the Soviet heritage. To recall, Soviet leaders were very cautious in their apprehension of nuclear war. To the point, moreover, that one can put forward the hypothesis, as troubling as it may seem, of a Russian fear of a disarming Western attack. It should be noted in this respect that all strategic forces (including defensive ones) were effected by the decision of 27 February.

On the Western side, cooler heads clearly prevailed. None of the three nuclear powers resorted to any provocative gestures, and all sought to cool the temperature. In France, the foreign minister merely recalled that NATO was a “nuclear alliance”.[22] Emmanuel Macron’s message to the armed forces referred to “permanent postures”, without explicitly mentioning nuclear deterrence.[23] The sortie of a third French SSBN, reported by the press, was not officially communicated. The US STRATCOM reported that it had not recommended any change in nuclear posture.[24] As for the United States, it is known that it has postponed an intercontinental surface-to-surface missile test and has not communicated on a hypersonic missile test.[25] It did, however, conduct no less than four test launches of Trident-2 D5 ballistic missiles in June. In addition, Western countries have sought to dissuade Moscow from using chemical weapons by suggesting that Russia would pay a “high price”.[26]

Overestimating the risk of nuclear weapons use

The risk of a nuclear weapon being used seems extremely low unless an escalation of the conflict leads Moscow to consider that there could be a threat of an “existential” nature for Russia.

It follows from official texts and exercises that the Russian nuclear threshold has been raised from what it was until the 2000s. The 2020 doctrine envisages four possible thresholds: (i) the detection of a missile attack against Russian territory (“launch on warning”); (ii) a nuclear attack or an attack conducted with other weapons of mass destruction against Russia or its allies; (iii) attacks leading to a paralysis of the Russian command and control system; and (iv) a conventional attack that would threaten the very existence of Russia.[27] The conflict must end on terms that are “acceptable” to Russia. While large-scale Russian exercises involve the use of numerous dual-use capabilities (and are frequently accompanied by strategic force exercises), there do not appear to be any recent examples of overtly simulated use of nuclear weapons in the theater during these exercises.[28]

To be sure, “the existence of Russia” could have a rather broad definition from Mr. Putin's point of view and certain Western declarations may have added to Moscow's nervousness. In his speech on February 24, the Russian president seemed to indicate that Western policy was already posing a risk to the very existence of the state: “For our country, it is a matter of life and death, a matter of our historical future as a nation. This is not an exaggeration; this is a fact. It is not only a very real threat to our interests but to the very existence of our state and to its sovereignty. It is the red line which we have spoken about on numerous occasions. They have crossed it.”[29] Three days later, Mr. Putin reproached Western governments for “indulging in aggressive statements”, in faith of which he decided to modify the force posture.[30] This announcement caught the world's attention. What Mr. Putin termed as a “special combat regime” has given rise to multiple interpretations, but the explanations given later by the Minister of Defence, Sergei Shoigu, allow one to favor a de-dramatizing interpretation. It was about increasing the number of personnel serving permanently in the strategic force headquarters.[31] Mr. Putin may nevertheless have given the impression that he had extended the scope of Russia's vital interests beyond the mere military threat to the existence of the state.

However, Mr. Putin's public statements seem to have been designed to impress and even frighten public opinion. Some of the best experts on Russia advise observers not to believe the Kremlin's “nuclear bluff”.[32] Moreover, it seems that the procedure for the engagement of nuclear forces is inherited from the Soviet system of collective decision: there is evidence that at least the Defense Minister, if not the Chief of Defense Staff, would have to give his consent.[33]

Then again, Russia has indicated on several occasions that even a non-nuclear attack against territory considered to be Russian – including Crimea – could fall into this category. On February 7, Mr. Putin stated that “if Ukraine joined NATO and decided to take back Crimea through military means, European countries would automatically be drawn into a military conflict with Russia,” which is “one of the world’s leading nuclear powers, and is superior to many of those countries in terms of the number of modern nuclear force components.”[34] Putin had said in 2015 that he would have been ready to put Russian nuclear forces on alert if Crimea had been threatened.[35] In other words, the notion of an “existential threat” to Russia does indeed seem to apply to the scenario of a direct attack against a territory considered by Moscow to be legally Russian.

What’s next? Consequences for nuclear deterrence

Has the nuclear deterrent in general been strengthened, at this stage, by the war in Ukraine? It is certain in any case that it has not been delegitimized, but a precise answer to the question is difficult because it depends on perceptions of its effectiveness. For Russia, it is certainly seen as strengthened by the fact that it avoided the direct intervention of NATO countries in the conflict (to say nothing of attacking Russian territory).

The Kremlin has made it clear that it now plans to more or less imitate NATO by promising Belarus a “nuclear sharing” role, perhaps to discourage Poland from joining NATO mechanisms.[36] However, one may wonder about the chances of such an initiative becoming a reality. First of all, by referring to an airborne capability, to the Sukhoi-25 (and not the Sukhoi-35 as requested by his Belarusian counterpart), the Russian president has not indicated any desire to reconstitute a modern nuclear capability. Secondly, it would be necessary to train Belarusian pilots for this purpose, and to reactivate the old storage sites from the time of the Soviet Union. And would the Kremlin's confidence in Minsk be sufficient to go down this road?

In the medium term, a lasting weakening of the Russian army could lead Moscow to return to its posture of the 1990s and 2000s, in which nuclear weapons were used to compensate for its inferiority on  the conventional battlefield.

Conversely, it is not certain that Western deterrence will emerge strengthened from the war in Ukraine. To be sure, it may have prevented Russia from escalating to extremes or attacking NATO countries. The reasonable attitude of the Western states in the nuclear field has undoubtedly contributed to neutralizing Moscow's ability to play its nuclear trump card. However, one should also recall that Western deterrence (the threat of “massive” sanctions) failed. This may have been due to the asymmetry of the stakes, but also, perhaps, due to the Kremlin's conviction that the West could not or would not want to impose such strong sanctions because of European dependency on Russian oil and gas, or fear of countersanctions. Also, nuclear deterrence may appear weakened if one considers that Russian nuclear capability has been the main obstacle to greater involvement in support of Ukraine (the comparison with Kosovo may come to mind: NATO did not hesitate in bombing Belgrade). In this case, it would mean that the use of deterrence to neutralize opposing coercion does not work. In addition, US debates about the response to nuclear weapon use – which many believe would be non-nuclear in nature – affect the credibility of the US deterrent.[37] One wonders whether Mr. Biden's reminder in his May 31 op-ed appeared sufficiently convincing to the Kremlin: “Let me be clear: Any use of nuclear weapons in this conflict on any scale would be completely unacceptable to us as well as the rest of the world and would entail severe consequences.”[38]

The NATO extended deterrence is, however, validated by the war in Ukraine. Germany, by announcing its intention to acquire US F-35 fighter-bombers, has clearly chosen continuity in this area. Poland has made it known that it could receive American nuclear weapons.[39] And because of the change in the status of Belarus (the referendum of February 27 authorizing the stationing of nuclear weapons on its territory), a debate on a possible modification of NATO's nuclear posture in the East is bound to open. Moreover, in Japan, some experienced voices are calling for Tokyo to benefit from “nuclear sharing” as well.[40]

What’s next? Implications for non-proliferation and disarmament

The holding of the first Meeting of States Parties to the Treaty on the Prohibition of Nuclear Weapons, in June 2022, showed that the gap between the hopes of the disarmament community and the strategic realities was as wide as ever. In fact, it is hard to imagine how the war in Ukraine could lead to a return to disarmament in the near future. With regard to arms control, it is difficult to see how the US-Russian dialogue on “strategic stability” could be resumed any time soon. Moreover, a possible deployment of Russian nuclear weapons in Belarus would create a situation not seen since the early 1990s.

With regard to non-proliferation, it has been suggested again that Ukraine would not have been attacked if it had retained “its” nuclear weapons.[41] But this idea has little credibility: not only is it admitted that Kiev would probably not have been able to use these weapons, but it is hard to see how the country could, in this scenario, have escaped a pariah status, which would certainly have prevented it from drawing closer to the European Union and NATO. The fact remains that the narrative that “once again, a country that has renounced nuclear weapons has been attacked” (just as Iraq, Libya, even Syria were) will hold  some political credibility. North Korea and Iran will find themselves – if need be – reinforced in their nuclear approach. And the argument could also be used in the internal debates of states considering, seriously or not, embarking on a nuclear adventure. Moreover, if the security guarantees given by the United States to its allies have no reason to be weakened by the war in Ukraine, the assurances given in the framework of non-proliferation – whether on a general basis (the Nonproliferation Treaty) or on a specific basis (the Budapest Memorandum on Security Assurances given to Ukraine in 1994) – could be weakened or even delegitimized.[42] All this does not bode well for the future of nuclear non-proliferation.


[1] Ukraine inherited part of the Soviet nuclear weapons arsenal when it became independent in 1991. It accepted to give them up in 1994 as a quid pro quo for “security assurances” of non-aggression given by the main nuclear powers, including Russia. It signed the Nuclear Nonproliferation Treaty (NPT) and became a Non-Nuclear Weapons State.

[2] See, for instance, Max Fischer, “As Russia Digs In, What’s the Risk of Nuclear War. ‘It’s Not Zero’,” The New York Times, March 22, 2022,; and J. Peter Scoblic & David R. Mandel, “Opinion: How to Assess the Risk of Nuclear War without Freaking Out,” CNN, June 28, 2022,

[3] Jeffrey Lewis & Aaron Stein, "Who Is Deterring Whom? The Place of Nuclear Weapons in Modern War," War on The Rocks, June 16, 2022,

[4] The Kremlin, “Address by the President of the Russian Federation,” February 24, 2022,

[5] Luke McGee & Claire Calzonetti, "Putin Spokesman Refuses to Rule Out Use of Nuclear Weapons If Russia Faced an 'Existential Threat'," CNN, March 22, 2022,

[6] "Putin's Spokesman Dmitry Peskov on Ukraine and the West: 'Don't Push Us into the Corner'," PBS NewsHour, March 28, 2022,

[7] Daniel Boffey, "Russia Reasserts Right to Use Nuclear Weapons in Ukraine," The Guardian, March 26, 2022,

[8] Olena Roshina, "Lavrov Denies the Possibility of a Nuclear Strike on Ukraine," Pravda, April 19, 2022,

[9] "Russia Is Against Use of Nuclear Weapons in Ukraine, Lavrov Says,” Bloomberg, April 19, 2022,

[10] "Sarmat Missile Will Make Russia Foes 'Think Twice' - Putin," The Moscow Times, April 20, 2022,

[11] The Kremlin, “Meeting with Council of Lawmakers,” April 27, 2022,

[12] Scott D. Sagan & Jeremi Suri, "The Madman Nuclear Alert. Secrecy, Signaling, and Safety in October 1969," International Security 27, no. 4 (2003),

[13] William J. Broad, "How America Watches for a Nuclear Strike," The New York Times, April 5, 2022,

[14] David E. Sanger et al., "US Makes Contingency Plans in Case Russia Uses Its Most Powerful Weapons," The New York Times, March 23, 2022,

[15] David E. Sanger & William J. Broad, "Putin's Threats Highlight the Dangers of a New, Riskier Nuclear Era," The New York Times, June 1, 2022,

[16] Joseph R. Biden Jr., "President Biden: What America Will and Will Not Do in Ukraine," The New York Times, May 31, 2022,

[17] NATO, Russia's Strategic Exercises: Messages and Implications, NATO Strategic Communications Center of Excellence, July 2020,

[18] William M. Arkin, "Exclusive: Putin's Captured War Plans Show His Ukraine Ambitions Shrinking," Newsweek, May 13, 2022,

[19] See, for instance, Belle de Jong, “Russian Media Hysteria: Kremlin Channels Continue to Threaten Europe with Nuclear Missiles,” The Brussels Times, May 2, 2022,

[20] Kristin Ven Bruusgaard, "Understanding Putin's Nuclear Decision-Making," War on the Rocks, March 22, 2022,

[21] Pyotr Topychkanov, "Could Russia Use the Nuclear Option?" The Moscow Times, May 16, 2022,

[22] Anthony Audureau and AFP, "Ukraine: Le Drian Reminds Putin That 'the Atlantic Alliance Is Also a Nuclear Alliance,'" BFM-TV, February 24, 2022,

[23] “Message from President Emmanuel Macron to the Armed Forces,” Elysée, February 28, 2022,

[24] Joe Gould, "No Changes Coming to US Nuclear Posture after Russian Threat," Defense News, March 1, 2022,

[25] Oren Liebermann, "US Tested Hypersonic Missile in Mid-March but Kept It Quiet to Avoid Escalating Tensions with Russia," CNN, April 5, 2022,

[26] Libby Cathey & Shannon K. Crawford, "Biden Warns Russia Will Pay 'Severe Price' If It Deploys Chemical Weapons," ABC News, March 11, 2022,

[27] The Ministry of Foreign Affairs of the Russian Federation, Basic Principles of State Policy of the Russian Federation on Nuclear Deterrence, June 8, 2020,

[28] Bruno Tertrais, “Russia’s Nuclear Weapons: Worrying for the Wrong Reasons,” Survival 60, no. 2 (2018),

[29] The Kremlin, “Address by the President of the Russian Federation,” February 24, 2022,

[30] The Kremlin, “Meeting with Sergei Shoigu and Valery Gerasimov,” February 27, 2022,

[31] "Russian Nuclear Forces Placed on High Alert after Putin Order - Interfax," Euronews, March 1, 2022,

[32] Olga Oliker, "Putin's Nuclear Bluff: How the West Can Make Sure Russia’s Threats Stay Hollow," Foreign Affairs, March 11, 2022,

[33] Jeffrey G. Lewis & Bruno Tertrais, The Finger on the Button: The Authority to Use Nuclear Weapons in Nuclear-Armed States, CNS Occasional Paper 45, Middlebury Institute of International Studies at Monterey, February 2019,

[34] The Kremlin, “News Conference Following Russian-French Talks,” February 8, 2022,

[35] Laura Smith-Spark, "Russia Was Ready to Put Nuclear Forces on Alert over Crimea, Putin Says," CNN, March 16, 2015,

[36] The Kremlin, “Meeting with President Lukashenko of Belarus,” June 25, 2022,

[37] Eric S. Edelman & Franklin C. Miller, "Biden Is Trying to Deter Putin from Using Nukes. His Staff Isn't Helping," The Bulwark, June 15, 2022,

[38] Joseph R. Biden Jr, "President Biden: What America Will and Will Not Do in Ukraine," The New York Times, May 31, 2022,

[39] Shane Croucher, "NATO's Poland 'Open' to Hosting US Nuclear Weapons," Newsweek, April 3, 2022,

[40] Toby Dalton, "Nuclear Nonproliferation After the Russia-Ukraine War," Georgetown Journal of International Affairs, April 8, 2022,

[41] See, William J. Broad, “Ukraine Gave Up a Giant Nuclear Arsenal 30 Years Ago. Today There Are Regrets,” The New York Times, February 5, 2022,

[42] See, Ariel E. Levite, "Why Security Assurances Are Losing Their Clout as a Nuclear Nonproliferation Agreement," The Bulletin of the Atomic Scientists, June 29, 2022,

: 19-July-2022

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