Nuclear deterrence in the Ukraine war: Diplomacy of violence

Introduction

Russia’s war of aggression against Ukraine has been fought under the shadow of nuclear weapons. Russia’s persistent and aggressive nuclear rhetoric during the war has provoked concerns in the West about Russia’s possible readiness to use nuclear weapons against Ukraine or escalate the war into a direct conflict with NATO. Indeed, there is a widespread understanding that Russia’s nuclear weapons have been the primary reason why NATO has not intervened in the war. Nonetheless, Ukraine has been given military aid that has been crucial to its success in resisting the Russian invasion. Moreover, the United States has communicated to Russia that it would respond if Russia used nuclear weapons. Although publicly the nature of the possible US response has been left ambiguous, such a threat is only possible because it is backed by nuclear deterrence.

Consequently, the war in Ukraine is fought under mutual nuclear deterrence in the tradition of the Cold War. This Briefing Paper analyses how nuclear deterrence operates in the Ukraine war. First, it discusses how nuclear deterrence works to limit wars between nuclear-armed states. It then maps out the deterrence strategies of Russia and the US. Finally, the paper proposes that the supporters of Ukraine take into account the limits of Russia’s nuclear deterrence and substantially increase the military aid to Ukraine with the goal of defeating Russia.

Diplomacy of Violence

Nuclear weapons have been used in military operations only twice, by the US against Japan in the Second World War, and it is not a coincidence that the event occurred when the US was the sole possessor of nuclear arms. When the enemy also has nuclear weapons, their use on the battlefield may well provoke a retaliation in kind. Moreover, even if one’s current enemy is not armed with nuclear weapons, its allies or one’s future enemies might be. If nuclear weapons were used, all these possible enemies would inevitably review their strategic plans. In these conditions, the costs of the military use of nuclear weapons nearly always outweigh the gains. Accordingly, nuclear weapons have not been used on the battlefield since 1945.

Nuclear weapons have, however, been used as instruments of coercion numerous times since they were invented. One needs not look further than the Cold War era confrontations such as the Cuban missile crisis for historical examples. Concessions can be extracted, and political settlements may be forced by resorting to nuclear blackmailing. Moreover, because nuclear deterrence continues to operate during any war between nuclear-armed adversaries, it has permanent effects on their military strategies and the nature of wars. Accordingly, Thomas Schelling noted in his landmark study that in the era of nuclear weapons, military strategy can no longer be thought of only as a science of military victory but also as an art of coercion, intimidation and deterrence, or, as he calls it, “diplomacy of violence”.^[1]

This entails two practical consequences: 1) because nuclear escalation would cause all parties terrible strategic harm, adversaries in nuclear-related wars have limited their use of force below their true capabilities; and 2) because there is no final arbiter of the proper limits of war, they must be negotiated with one’s adversaries. Schelling pointed out that two primary issues are then bargained over: the outcome of the war, and the way to wage war.

Schelling noted that limited wars in which nuclear deterrence is used are competitions in risk-taking and tolerance, resembling tests of nerve as much as tests of strength. The critical target is the adversary’s mind as much as any object on the battlefield. A particularly unscrupulous actor may intend to create a risk of nuclear escalation, or a perception of such a risk, and use it to its advantage, but the realization of the risk is not intended.

In this game, the adversaries make strategic moves by issuing promises and threats, whether in words or deeds, which are intended to facilitate the outmanoeuvring of the enemy. For example, when Ukraine struck the Engels airbase in December 2022, it renegotiated the theatre of military operations and demonstrated that long-range strikes deep inside Russia against its strategic bombers did not escalate the war.

Because threats must be credible to be successful, decision-makers have historically issued only carefully worded and implicit nuclear threats. Drastic commitments may be counterproductive because if the bluff is called, one must either meet one’s commitments or watch the credibility of one’s future threats crumble. Russia’s nuclear rhetoric and deterrence strategy in the Ukraine war has also been based on this blueprint. It follows the Cold War-era tradition of innuendo, implicit threats, and demonstrations of nuclear capabilities, but no real commitments.^[2]

Russia’s deterrence strategy in the Ukraine war

Russia’s primary goal since the invasion began has been to deter NATO’s intervention in the war, but it has also attempted to restrain Western interference in the conflict, particularly in the form of military aid. Implicit nuclear threats have, however, focused on deterring intervention.

There is in fact nothing new in Russia’s nuclear sabre-rattling for such purposes. In 2014–2015, Russia instrumentalized its nuclear arsenal in a similar fashion to support its first invasion of Ukraine. As Russian forces occupied Crimea in March 2014, Russia ordered its nuclear forces to snap exercises that included test launches of several intercontinental-range missiles. Further drills were conducted during the course of the war, including another snap exercise for nuclear forces during the early 2015 offensive of Russia-led forces. Meanwhile, Russia increased its bomber patrols to an unprecedented scale. Throughout the war, these military activities were accompanied by veiled nuclear threats issued by Russian officials such as Foreign Minister Sergey Lavrov and aired in the Russian state media. After the end of the large-scale military operations in 2015, President Vladimir Putin insisted that he had been ready to put Russia’s nuclear forces on alert when Russia occupied Crimea in March 2014. According to Jacek Durkalec and Dave Johnson, the purpose of these actions was to deter NATO from intervening in the war by ramping up the perception of the risk in accordance with Schelling’s concepts.^[3] Russia was successful and even managed to deter NATO from delivering lethal aid to Ukraine in 2014–2015.

Russia followed this basic script in 2022 and began to frame the war as a possible nuclear conflict just before the invasion began, when it initiated a command exercise of its strategic deterrence forces on 19 February. The exercise included test launches of intercontinental-range missiles. These exercises have usually been held in the autumn after the yearly joint strategic exercise, but in 2021, the exercise was not organized, and it appears to have been postponed to coincide with the invasion of Ukraine. When the invasion began on 24 February, President Putin issued an implicit nuclear threat to NATO by referring to Russia’s nuclear forces and threatening anyone attacking Russia with consequences never seen in history.^[4] This was soon followed by an order to assign Russia’s deterrence forces to special combat readiness. What the order entailed was not publicly revealed, but one expert suggested that command and control systems were now put into a state in which orders could be transmitted.^[5] These acts were done in rapid succession probably to paralyse Western support during what was expected to be a quick military operation.

Although the capture of Kyiv failed, Russia continued to maintain an implicit nuclear threat over the conflict. At the same time, it attempted to confuse the public by accusing the West of irresponsible nuclear rhetoric. Russian officials also denied that Putin had even meant that Russia could use nuclear weapons in the war. This underlines another principle of Russia’s nuclear rhetoric during the war: the obfuscation of what has actually been said and meant. When asked about the conditions of nuclear use, Russian officials have typically been ambiguous and quoted Russia’s nuclear doctrine, which states that Russia may use nuclear weapons when its existence is under a threat. The nuclear rhetoric was accompanied by a test launch of Russia’s new Sarmat intercontinental ballistic missile (ICBM) in late April 2022. Russian propagandists have also speculated about the possible destruction that Russia’s nuclear attacks against Western countries could cause, referring to new strategic nuclear weapons such as Sarmat or the Poseidon underwater drone.^[6]

The Western media has been as a platform for disseminating this information. This is consistent with the Russian deterrence thinking, in which the object of deterrence is not only the military-political leadership of its adversary but also its public.^[7] The deterrence strategies of democracies depend on public support, and if Russia can convince the Western public that aiding Ukraine may provoke the escalation of the war, decision-makers may not find the support they need for taking crucial decisions. This creates challenges for the media covering the war, which needs to balance between accurate reporting and being aware of what Russia is trying to use it for. Russia’s deterrence strategy also depends on the public not being aware of the deterrence dynamics of the war, namely that the West has agency as well, and that NATO has the capabilities to ensure the credibility of its deterrence posture. The Sarmat and Poseidon systems had not yet even been deployed in 2022, which illustrates the absurdity of referring to them to threaten Western decision-makers.

If the Western media is not available as a platform, threats may not be as effective. In August 2022, Deputy Foreign Minister Sergei Ryabkov emphasized that NATO’s intervention would increase the risk of nuclear escalation. At the same time, he specified that the key word in Russia’s nuclear doctrine is “aggression” (and not “existence”, for example). According to Ryabkov, nuclear weapons could be used “as a response to an attack – self-defence in emergency situations”. This statement, if taken at face value, might have sparked concerns in the West that Russia’s doctrinal nuclear threshold was lower than thought. However, his statement was not widely reported by the Western media, and it appears to have had little or no influence on the Western perceptions about the nuclear risks in the war. A month later, Ryabkov stated that Russia’s doctrine had not changed, although this was never the point of his original statement.^[8] This statement also did not receive wide coverage in the Western media.

Russia issued the clearest nuclear threats since the opening phase of the war when it began to prepare for the illegal annexation of the occupied Ukrainian territories. In September 2022, Putin ambiguously referred to Russia’s nuclear weapons again and stated that Russia may use all means at its disposal to protect itself and its territorial integrity, adding that he was not bluffing. Putin invoked nuclear weapons in a similar fashion in his speech on the illegal annexation of the occupied Ukrainian oblasts in September.^[9] The bluff was called when Russia retreated from Kherson. Since then, Russian nuclear rhetoric has been lower-profile but intermittent.

Russia’s nuclear threats have been implicit and have always contained a way out for Russia. Avoiding ironclad commitments regarding the use of nuclear weapons appears to be a priority for even aggressive decision-makers such as President Putin. At the same time, Russia’s avoidance of commitments in the Cold War tradition is not only evidence that it seeks to avoid a direct clash with NATO, but also that its leaders are rational actors, capable of sticking to their script. There is not much new in Russia’s deterrence strategy, as it retains the basic form of 2014–2015.

Russia’s nuclear threats suffer from a lack of credibility because even the use of nuclear weapons would not guarantee it a military victory. With the Ukrainian forces properly dispersed, sufficient battlefield advantage could not be gained with a single or even a grouped nuclear strike.^[10] Russia could only hope for capitulation. Such a result could be expected if Russia was using nuclear deterrence for defending its homeland against invaders, but in this war, Ukraine faces the existential threat, not Russia. Ukraine would probably continue fighting even if nuclear weapons were used. Japan may have surrendered in 1945, but it had no nuclear-armed allies that could help it. The US, however, has committed to intervening on behalf of Ukraine.

The US response

Russian nuclear rhetoric has been meaningless in clarifying its actual nuclear threshold as the US deterrence posture and actions continue to shape which threats are credible and which actions are sensible. During the 2022 invasion, the US 1) has sought to diminish the effects of Russia’s nuclear rhetoric on the Western public and 2) has privately and publicly communicated to Russia its intention to retaliate if Russia uses nuclear weapons. The US rhetoric hardened when Russia’s defeat became more likely, and the US saw a greater possibility that Russia might escalate the war.

During the opening phase of the war, the US tried to control the public perception of nuclear risks by not giving Russia material to work on. In March 2022, the US postponed the test launch of the Minuteman III ICBM and did not publicize the test of its new HAWC missile system until sometime after the test had been conducted. By cancelling or keeping its missile tests secret, the US reduced Russia’s opportunities to ramp up the fear of nuclear war among the Western public.

Once Russia’s victory became less likely in the spring of 2022, the US began to publicly remind Russia of its deterrence, although the language remained subtle. The most severe threat was issued in May by President Joe Biden, who stated that there would be “severe consequences” if Russia used nuclear weapons."^[11]

According to insiders, after the liberation of Kharkiv in the autumn of 2022, US authorities considered it more likely that Russia might try to avoid defeat by escalating the war. Consequently, the US adopted a tougher deterrence posture and began to publicly threaten Russia that it would respond if Russia used nuclear weapons. The US also revealed that it had been communicating to Russia for months that the use of nuclear weapons would have “catastrophic consequences”, which had been privately spelled out to Russia. In early October, anonymous officials reiterated that the US was considering various responses if Russia used nuclear weapons demonstratively or on the battlefield. Soon after, President Biden stated that he did not believe in the possibility of using a tactical nuclear weapon without it leading to Armageddon.^[12]

By making such severe threats publicly, the US essentially committed itself to a military retaliation if Russia escalated the war, although the retaliation would highly likely be non-nuclear. Political consequences would simply not be enough to maintain US credibility. By hinting at Armageddon, President Biden also implied that the US would continue fighting even if Russia retaliated to the US response with subsequent nuclear attacks. By committing itself to a retaliation, the US has essentially removed the possibility that Russia could ensure its victory in the war with a one-time nuclear use.

The US threats have been more credible than those of Russia because the US has threatened to do less than Russia but still stands to lose a lot if it does not abide by its commitment. If the US did not retaliate to Russia’s nuclear use, its extended deterrence guarantees for NATO would be taken less seriously. China might deem the US readiness to defend Taiwan much weaker and might be emboldened to solve the issue militarily. The US deterrence strategy benefits from these potential consequences because Russia knows that by inaction, the US might cause itself tremendous strategic harm. Moreover, the entire world community, including Russia’s partners such as China and India, oppose breaking the nuclear taboo. If Russia ever detonated nuclear weapons for the purpose of winning the war in Ukraine, the war would no longer be about Ukraine. It would be about whether nuclear weapons can be used to win wars of aggression. The US and NATO would not meet opposition if their answer was a resolute “no”.

Crucially, the US issued its threats pre-emptively, before there had been any indications that Russia might use nuclear weapons or make nuclear threats that would lead to commitments. By committing first, the US prevented Russia from tying its hands with its own nuclear threats. Even if Russia was defeated and lost the occupied Ukrainian territories, the credibility of Russia’s nuclear deterrence with regard to defending its homeland would not be questioned. Russia knows that it can lose the stolen territories safely, despite what it publicly says, because it knows that the West treats them as parts of Ukraine.

Conclusion

Coercion, deterrence, and diplomacy of violence permeate the Ukraine war. Nuclear blackmailing has been an integral part of Russia’s military strategy. The US has been forced to respond, and its deterrence has been crucial in ensuring Ukraine’s survival. The war confirms the enduring importance of nuclear deterrence for the security of NATO.

Russia’s strategy is failing, however, because it uses nuclear deterrence for something it is not suited for: as a coercive tool in a protracted war of conquest. As long as such nuclear threats can be countered with a threat to retaliate, their credibility is low because the benefits cannot outweigh the costs in the vast majority of circumstances. If Kyiv had fallen quickly, Russia’s strategy would have been more effective because then the West would have been forced to make the choice whether to intervene and whether it was ready for risk escalation. Now it can also deliver military aid to Ukraine, which can use that aid to liberate occupied territories, while Russia has to decide whether it is ready for risk escalation. Russia could strike at the supply convoys, but it knows that by doing so it might provoke the intervention of NATO and thus ensure its own defeat. Nevertheless, vigilance is required, and the US may have to adjust its deterrence posture in the future.

Discussions about nuclear thresholds tend to be too simple because they often do not take into account the adversary’s ability to shape that threshold. Successful threats are ones that are not carried out. Yet an important part of a successful threat is the adversary’s recognition that the threat is credible. Deterrence is also credited to one’s adversary. During the Cold War, the Eastern Bloc and occupied states were effectively regarded as belonging to the Soviet Union’s sphere of influence. The Soviet Union could then, under the cover of its nuclear shield, stamp out the Hungarian uprising in 1956 and invade Czechoslovakia in 1968 without the interference of the West. The US may have spent billions of US dollars to assist the Mujahideen of Afghanistan during the Soviet-Afghan war in 1979–1989, but even that operation was covert. Today, the West does not recognize spheres of influence, and Ukraine has therefore received unprecedented and open support.

The West should understand the limits of Russia’s nuclear coercion and remove self-imposed restrictions regarding the weapons it delivers to Ukraine. The delivery of HIMARS has shown what advanced weapons can do for Ukraine’s war effort. The next step is to tailor the military aid to Ukraine’s operational needs, and with the intention of defeating Russia.

It is in the interests of the West that Russia can derive as little benefit as possible from its nuclear blackmailing. If Russia discovers an effective way to utilize its nuclear deterrence, it is likely to use it in the future, much like its 2022 nuclear script was based on its 2014–2015 strategy. By having withheld and delayed the delivery of key systems, the West has already indicated to Russia that nuclear coercion can be beneficial in wars of aggression. By acting either decisively or indecisively, the West will nonetheless shape the future culture of interstate conflicts. Russia’s defeat will discourage further opportunism, while displays of weakness by the West will encourage it.

Endnotes

[1] Schelling, Thomas (1966) Arms and Influence, Yale University Press. This section relies heavily on Schelling’s work.

[2] For the chronology of the Russian and the Western rhetoric until September 2022, see Arndt, Anna Clara and Liviu Horovitz (2022) Nuclear rhetoric and escalation management in Russia’s war against Ukraine. SWP Working Paper, https://www.swp-berlin.org/publications/products/arbeitspapiere/Arndt-Horovitz_Working-Paper_Nuclear_rhetoric_and_escalation_management_in_Russia_s_war_against_Ukraine.pdf.

[3] Durkalec, Jacek (2015) Nuclear-Backed “Little Green Men”: Nuclear Messaging in the Ukraine Crisis. Report, the Polish Institute of International Affairs. https://css.ethz.ch/en/services/digital-library/publications/publication.html/193514; Johnson, Dave (2015) Russia’s approach to conflict – Implications for NATO’s deterrence and defense. Research Paper 111, NATO Defense College, https://www.ndc.nato.int/news/news.php?icode=797.

[4] Putin, Vladimir (2022a) “Obrashtsheniye Presidenta Rossiiskoy Federatsii”, President of Russia, 24 February 2022, http://kremlin.ru/events/president/news/67843.

[5] Chernenko, Elena (2022) “Prikazaltelnoye vystupleniye”, Kommersant, 28 February 2022, https://www.kommersant.ru/doc/5237409.

[6] The Moscow Times (2022) “Russia’s Lavrov Accuses West of Fixating on 'Nuclear War’”, 3 March 2022, https://www.themoscowtimes.com/2022/03/03/russias-lavrov-accuses-west-of-fixating-on-nuclear-war-a76735; McGee, Luke and Claire Calzonetti (2022) “Putin spokesman refuses to rule out use of nuclear weapons if Russia faced an ‘existential threat’”, CNN, 22 March 2022, https://edition.cnn.com/2022/03/22/europe/amanpour-peskov-interview-ukraine-intl/index.html; PBS (2022) “Putin’s spokesman Dmitry Peskov on Ukraine and the West: ‘Don’t push us into the corner’”, 28 March 2022, https://www.pbs.org/newshour/show/putins-spokesman-dmitry-peskov-on-ukraine-and-the-west-dont-push-us-into-the-corner; The Telegraph (2022) ”Russian state TV threatens nuclear strike on UK and warns of radioactive tidal wave”, The Telegraph, 2 May 2022, https://www.youtube.com/watch?v=r4eJvwtQJu4.

[7]“Sderzhivaniye strategicheskoye”, Voyennyi entsiklopedicheskiy slovar [Military Encyclopaedia], MOD Russia, https://encyclopedia.mil.ru/encyclopedia/dictionary/details.htm?id=14206@morfDictionary.

[8] Postnikova, Ekaterina (2022), "Primineniye yadernogo oruzhiya vozmozhno tolko v poryadke otveta na napadeniye", Izvestiya, 22 August 2022, https://iz.ru/1381726/ekaterina-postnikova/primenenie-iadernogo-oruzhiia-vozmozhno-tolko-v-poriadke-otveta-na-napadenie; TASS (2022) “Senior diplomat says Russia didn’t change its doctrinal approaches to nuclear weapons”, 26 September 2022, https://tass.com/politics/1513565.

[9] Putin, Vladimir (2022b) “Obrashtsheniye Presidenta Rossiiskoy Federatsii”, 21 September 2022, President of Russia, http://www.kremlin.ru/events/president/news/69390; Putin, Vladimir (2022c) “Podpisaniye dogovorov o prinyatii DNR, LNR, Zaporozhkoy i Hersonskoy oblastey v sostav Rossii”, 30 September 2022, President of Russia, http://kremlin.ru/events/president/news/69465.

[10] Alberque, William (2022) Russia is unlikely to use nuclear weapons in Ukraine. IISS Analysis, https://www.iiss.org/blogs/analysis/2022/10/russia-is-unlikely-to-use-nuclear-weapons-in-ukraine.

[11] Biden, Joseph R. (2022) “What America Will and Will Not Do in Ukraine”. The New York Times, 31 May 2022, https://www.nytimes.com/2022/05/31/opinion/biden-ukraine-strategy.html.

[12] Sonne, Paul and John Hudson (2022) “U.S. has sent private warnings to Russia against using a nuclear weapon”, The Washington Post, 22 September 2022, https://www.washingtonpost.com/national-security/2022/09/22/russia-nuclear-threat-us-options/; Smith, Alexander (2022) “U.S. warns Russia of 'catastrophic' consequences if it uses nuclear weapons”, NBC, 26 September 2022, https://www.nbcnews.com/news/world/russia-catastrophic-consequences-nuclear-weapons-ukraine-us-warns-rcna49365; Sciutto, Jim (2022) “US considering responses to possible Russian escalation in Ukraine, including its potential use of tactical nuclear weapons”, CNN, 3 October 2022, https://edition.cnn.com/2022/10/03/politics/ukraine-russia-putin-nuclear-weapons-us; Fossum, Sam, Kaitlan Collins and Paul LeBlanc (2022) “Biden offers stark ‘Armageddon’ warning on the dangers of Putin’s nuclear threats”, CNN, 6 October 2022, https://edition.cnn.com/2022/10/06/politics/armageddon-biden-putin-russia-nuclear-threats/index.html.