Russia’s Nuclear Threats in the War against Ukraine

Moscow Expands the Role of Its Nuclear Arsenal

According to Russia’s official doctrine, nuclear weapons primarily guarantee the country’s sovereignty and territorial integ­rity. The deterrence principles published in 2020 reflect this stance. Accordingly, Mos­cow would use its nuclear forces in the event of a nuclear attack on Russia and/or if the existence of the state were threatened by conventional aggression.

Putin’s announcements during the war against Ukraine, however, suggest that for Russia’s leadership, the function of its nuclear arsenal goes beyond the narrow defensive role set out in the official doc­trine. Rather, the Kremlin seems to be using nuclear weapons to pursue expansive politi­cal goals. Indeed, Putin appears bent on shielding his conventional war of aggres­sion under a nuclear umbrella. Through his threats, he seeks to deter outside actors from interfering and to keep the conflict at a level that Russia considers a “local war”. In this way, nuclear weapons are a tool of intimidation and of escalation manage­ment.

Moscow’s rhetoric thus suggests that it is interpreting its own nuclear doctrine more broadly. Putin justified his war of aggres­sion by claiming that the United States was estab­lishing a hostile “anti-Russia” in Ukraine, a supposed reality that in turn represented a matter of life and death for Russia. This threatened nothing less than the existence and sovereignty of Russia, he said – a for­mulation echoing Russia’s nuclear doctrine. Moreover, Putin accused Ukraine of devel­oping nuclear weapons and other weapons of mass destruction, thereby further neces­sitating Russia’s intervention. This expan­sion of the doctrine and his own narratives appear to serve as a pretext for Putin to issue nuclear threats, even in the absence of a military threat to Russia.

Intentional Nuclear Use Remains Extremely Unlikely

In the current war, intentional or unintentional nuclear escalation has once again moved into the realm of possibility, as warned by UN Secretary-General António Guterres on March 14. The more one doubts Putin’s rationality, the greater these risks appear. Yet Russia’s decision to wage a war of aggression seems to have resulted not from irrationality but from faulty assumptions about its own capabilities, about the situation in Ukraine, and about Western solidarity with Kyiv. Therefore, it would make little analytical sense to outline sce­narios on the premise of Putin’s irrationality, especially since this would allow for few viable policy choices. Despite Moscow’s threats, both conceptual nuclear strategy considerations and historical experience suggest that under today’s circumstances the probability of an intentional use of nuclear weapons remains extremely low.

First, Russia would face existential costs if it were to attack NATO states with nu­clear weapons. For decades, Russia and the United States have relied upon the principle of mutual assured destruction. Both states have thousands of nuclear weapons that can be mounted on various delivery sys­tems; and this is meant to ensure that even after suffering a massive first strike, the attacked would still be able to carry out a retaliatory second strike. The balance is maintained as long as neither dares to launch a disarming attack on the other. However, this also means that even a rela­tively limited use of nuclear weapons carries the risk of massive escalation. The result would be extreme destruction with global consequences disproportionate to Putin’s political goals in the war against Ukraine.

Second, even a limited use of nuclear weapons in Ukraine would fundamentally alter the nature of the conflict and the interests of third parties. Even if the United States wants the war to end, for Washington it currently remains a regional conflict posing only a limited threat to US security interests. The situation would be different if Russia were to use nuclear weapons against Ukraine. If Moscow succeeded in using such arms without suffering massive con­sequences, this would affect how other nuclear-armed states – such as China or North Korea – assess the costs and benefits of nuclear options. This would put the US system of alliances under extreme pressure, as it would heighten the threat perception of countries such as Japan or Poland. It would also fundamentally alter Washing­ton’s interests – and thus its position towards military involvement – in the war in Ukraine. In addition, even Russia-friend­ly actors such as India or China would see their interest in sustaining a relatively stable international system threatened and would need to rethink their position vis-à-vis Moscow.

Third, Russia’s reputation would suffer enormously from a decision to carry out a nuclear strike. Indeed, it would be the first country to do so since 1945. This would run counter to Moscow’s long-standing interests in non-proliferation and would irrevocably transform Russia into a pariah state rather than its self-declared status as a guarantor of global stability. How the Kremlin assesses the risk of such a loss of prestige remains unclear, but it would, nonetheless, need to consider that its own population’s support for the war may dwindle.

Accidental Nuclear Use Remains Equally Unlikely

Even if there are no incentives to intention­ally use nuclear weapons, there is still the possibility of unintended escalation. Such a scenario could arise, for instance, if one party to the conflict misinterprets risky steps taken by another, thereby setting into motion a dangerous dynamic. For example, the shooting down of a Russian fighter air­craft violating NATO airspace or the delivery of important military equipment to Ukraine could escalate the conventional conflict, which would in turn increase the risk of nuclear weapons use. Technical problems, such as faulty radar signals, could also cause a purely accidental escalation.

However, even in these scenarios, the risk of nuclear use remains low. Nuclear escalation would not occur automatically even in the event of a direct confrontation between NATO and Russia, as both sides have a vital interest in avoiding such an out­come. As long as neither Washington nor Moscow think that the other side could improve its position by using nuclear weap­ons, an inadvertent escalation remains unlikely.

Historical comparisons, for example with the Cuban Missile Crisis, are only of limited usefulness. In 1962, the United States was much more involved in the crisis as it took place in its immediate geographic proximity; it was more invested, not only with respect to its own influence and security interests, but also in terms of its readiness to poten­tially escalate the situation. In today’s war in Ukraine, by contrast, Washington is refraining from taking reciprocal counter-measures in response to Putin’s nuclear threats.

Moreover, in many early Cold War crises a conventional attack would inevitably have resulted in either a nuclear response or the loss of critical territory. Given Rus­sia’s conventional superiority in Europe, the United States threatened that any con­ventional aggression there could lead to a devastating nuclear response. NATO’s principle of collective defence, its forward deployed US nuclear weapons and the fact that Europe, as one of the world’s three most important industrial centres, was critical to the US-led Western order, all lent further credibility to Washington’s com­mit­ment to follow through on this threat.

The current situation also differs from historical cases in the sense that, especially in the first phase of the Cold War, US-Soviet crisis communication channels were tech­nically limited and central control over nuclear weapons was patchy. All of this suggests that while conventional conflicts could very well spiral out of control, they are unlikely to cross the nuclear threshold unless both sides take a number of addi­tional escalatory steps – which currently remains a distant possibility.

Putin’s Intimidation Tactics

Russia’s nuclear rhetoric appears to be pri­marily a tool of intimidation and blackmail. By threatening such severe force, Putin is trying to compel others to accept his politi­cal demands. But who are these demands aimed at?

Russia is at war with Ukraine, but currently Kyiv does not seem to be the main target of Putin’s nuclear threats. Moscow would of course be able to completely destroy the country with nuclear weapons; but the Kremlin can only achieve its osten­sible long-term goals – namely, establishing control over Ukraine, limiting its sov­ereignty and imposing a neutral status that prevents it from moving closer to the EU and NATO – through the use of conven­tional force. The extreme destructive power of nuclear weapons is not suitable to achieve these ends.

Even in the event of a Russian defeat in Ukraine, nuclear threats would not be credible and nuclear demonstration strikes would most likely be ineffective. Moscow would have to convincingly signal that it was prepared to either launch multiple nuclear strikes on the Ukrainian military or to destroy cities with nuclear weapons. Russia would thus need to convey its wil­ling­ness to accept further disproportionate costs in its efforts to defeat Ukraine. The result would be a nuclear escalation that would be difficult to control. Other nuclear powers would need to respond to such a brazen violation of the international secu­rity order, and Russia’s international isola­tion would reach new heights. Putin’s speeches do suggest that Ukraine plays a major role in his imperial vision, but there is little to suggest that he would pay such a high price to obtain control over the country.

Moscow’s statements and actions in the current crisis support this logic. Putin has always directed his nuclear threats not at Ukraine but at the West. Their public nature also suggests that the threats are being addressed to the Russian and Western populations. With respect to its own citi­zens, the Kremlin must sustain the narra­tive that the West is hostile to Russia, and in doing so it justifies the high cost of sanc­tions. With respect to Western citizens, on the other hand, Moscow is probably seeking to intimidate them with the hope that they will exert pressure on their own governments to reject tough measures against Russia. The Kremlin has had some success in this regard, especially if one considers the lively discussions in Western media about the appropriate responses to the war, the palpable public concern about a poten­tial nuclear attack and the wave of prepara­tory measures taken by some, including a run on iodine tablets.

Escalation Scenarios

First and foremost, Putin’s threats appear to be directed at Western governments. In light of the unexpected resolve of Europe and the United States, Moscow may be wondering what further measures the West could take. Economically, sanctions are doing significant damage within Russia, but Europeans and Americans could constrain the Russian economy much further, for example by way of an energy embargo – that is, if they were willing to bear the asso­ciated costs. Militarily, NATO states have the theoretical ability to decide the out­come of the conflict solely through con­ven­tional means. However, they have so far refused to intervene, despite tangible pres­sure. For many Western politicians and experts, the costs and risks of a direct West­ern intervention do not currently seem justified. However, the Kremlin apparently considers the potential consequences of a possible expansion of Western involvement to be so dramatic that it sees the need to draw red lines. Thus, it apparently seeks to signal that direct interference could trigger extreme – that is, nuclear – counter-measures.

Putin’s red lines, however, are intentionally vague, as they are meant to deter as many Western activities as possible. Yet, this kind of strategic ambiguity creates risks as it is difficult for the West to assess what level of engagement in the conflict could trigger a nuclear escalation.

First, the risk of escalation would be significant – even without Putin’s explicit nu­clear threats – if NATO were to enter the war directly. Current research shows that Russia’s conventional inferiority vis-à-vis the United States could lead to an esca­lation, even though both sides would have an interest in keeping the conflict limited. For example, if Washington decided to expand the war by launching full-scale con­ventional attacks on Russia, thereby threat­ening the Russian regime, Moscow would not be able to counter this with a compar­able non-nuclear capability – and might therefore consider limited nuclear strikes. Western governments are wary of such an expanded con­flict with potential nuclear implications, given that it is difficult to separate con­ventional and nuclear esca­lation risks. Current decisions with respect to military planning and assistance offered to Ukraine will therefore likely be influenced by considerations of the extent to which they pose a risk of nuclear weapons use.

Such was the case in recent discussions over the potential delivery of combat air­craft to Ukraine. Experts expected this to offer only a moderate benefit to Kyiv; and they also assessed that it risked escalation. In the end, the idea was rejected. Some even called for a no-fly zone. It is highly con­troversial how this measure would be implemented and how great its military effectiveness would be, especially since ground combat has played a much more important role in the war than air operations so far. The main reason for rejecting the no-fly zone, however, was that it would require military intervention by the West and could hence trigger an open war between NATO and Russia.

Aside from direct Western entry into the war, a second scenario could also have the potential to significantly aggravate the situa­tion. Putin seems eager to preserve his personal position of power, which raises the question of the means he might resort to in order to secure his regime. This pre­sents the West with a double challenge. On the one hand, the Western states want to increase their economic and military pres­sure in order to impair Russia’s ability to wage war and thus bring about a change in policy. On the other hand, the threat of regime change could incentivise Putin to use nuclear weapons to signal that he would rather resort to extreme measures than relinquish power.

This scenario illustrates how difficult it is to separate the consequences of a West­ern military escalation in Ukraine from the ramifications of economic pressure on Russia. Although one might argue that this kind of defence of the regime is highly un­likely in relatively stable states like Russia, the developments of the past few weeks urge caution. For now, however, Putin’s power apparatus appears to be far from collapsing. This suggests that sanctions can be significantly increased before such questions surrounding regime collapse and nuclear escalation even arise.

Consequences for the International Order

The implications of this war for the Euro­pean security architecture and the global nuclear regime will depend heavily on the outcome of the conflict. Nevertheless, some consequences are already foreseeable. Per­haps the most problematic consequence concerns the role of nuclear weapons in international relations. Many governments will conclude that a nuclear arsenal, while not providing all-encompassing protection, can significantly increase the room for ma­noeuvre. On the one hand, nuclear weapons allow Russia to wage war in NATO’s vicinity without fear that the conventionally superior alliance will intervene directly. Arguably, there are many reasons why the alliance would decide to intervene, including: a destabilised Europe’s potential consequences for the international order; Moscow’s fla­grant breach of international law; and growing pressure within Western public opinion to intervene in the conflict. Many experts assess that NATO’s restraint is a consequence of an effective Russian nuclear deterrent. On the other hand, the West can supply arms to Ukraine on a large scale and inflict immense damage on the Russian economy without undue concern that Mos­cow might respond with nuclear weapons. As the war against Ukraine shows, the nu­clear balance between Russia and the West allows for a local conventional war outside NATO – the so-called stability-instability paradox thus seems to be confirmed.

These conclusions will also play an important role for the future of security cooperation with states beyond NATO and for reassurance within the alliance. This is especially true if Moscow manages to turn the war in its favour. Outside of the Western alliance, Georgia and Moldova, for example, perceive a greater Russian threat than ever before. This pushes NATO, and also the EU, to consider how such states’ desires for cred­ible security guarantees can be met.

Within the alliance, doubts may increasingly arise among the Eastern and Central European member states as to how desirable strategic stability between Mos­cow and Washington truly is. As noted, the standoff between the major powers allows Russia to leverage its regional conventional superiority vis-à-vis Ukraine and deter direct outside intervention. Even if eastern NATO members continue to trust US security guarantees, fears are likely to spread that Russia could achieve a rapid military success (or “fait accompli”) against other states, and shield those gains with its nuclear weapons.

This concern already prompted NATO’s decision in the end of March to strengthen its defences along its eastern and southeastern flanks. However, it would be extremely expensive and require a longer timeline to build up enough conventional capabilities to make a “fait accompli” scenario com­pletely impossible. If arms control were to erode completely, it is also conceivable that the United States would seek to undermine Russia’s strategic nuclear potential by ex­panding its own nuclear capabilities. How­ever, such an endeavour would carry a high risk of escalation.

At the international level, both the war and Moscow’s threats are undermining non-proliferation and arms control efforts. First, confidence in the value of nuclear doctrines, which are intended, among other things, to promote transparency and predictability, has been shattered. In the future, many states will rely much less on commitments made by Russia – but also by other nuclear powers. A hard-won gain in stability has thus been destroyed. Second, progress towards non-proliferation will also suffer. At present, the conflict seems to suggest that nuclear weapons not only ensure the continuity of political regimes but also insulate conventional disputes from direct foreign intervention. Regional actors with nuclear ambitions, such as Iran and Saudi Arabia, are watching closely.

Finally, the invasion of Ukraine has also undermined Russia’s credibility, which is a necessary condition for arms control talks. All consultations between Moscow and Washington were suspended in early March. While limited arms control measures could be added to the agenda as part of nego­tiations to end the war, more far-reaching steps remain unlikely in the long term. In­stead, Moscow is likely to increasingly rely on nuclear deterrence as a prolonged war and effective sanctions weaken Russia’s conventional capabilities and its regenera­tive capacity.

Policy Recommendations

Moscow’s nuclear threats must be taken seriously, but there is no reason for panic. First, when it comes to further aiding Ukraine’s war effort, it is important to realistically assess the likelihood of Russian nuclear weapons use. On the one hand, should NATO intervene directly in the war or actively work for regime change in Mos­cow, this could indeed generate further risk of nuclear escalation. However, the West is currently far from breaching the relevant thresholds. On the other hand, as the bru­tality of the war grows, public pressure to take steps that could bring the conflict closer to the nuclear threshold will increase. It may then become increasingly difficult for the Kremlin to assess the intent behind Western actions. Putin could underestimate the role of public opinion within democra­cies and interpret the West’s behaviour as strategically motivated. It is therefore im­portant that NATO states communicate their actions and intentions clearly and in close consultation – both to Moscow and to their own publics.

Second, Berlin should convey to the Ger­man public that the use of nuclear weapons is unlikely. This is also important because a prolonged war will entail high economic costs for Germany. With a public gripped by fears of nuclear war, it could become perceptibly more difficult for Berlin to con­tinue to support Ukraine. Therefore, the German government should better explain to the public the extent to which Putin is pursuing a destabilisation strategy while also highlighting where the real risks of a direct confrontation between NATO and Russia lie. Political decision-makers as well as experts should try to shed more light on this complex and disturbing topic.

Berlin also needs to seriously consider the long-term effects of Russia’s war of aggression and threatening gestures. Even the attempt to shield the invasion from outside intervention by using nuclear de­terrence will have negative consequences; and these consequences will be especially problematic should Russia win the war. The German government therefore has a strategic interest in preventing this out­come. While Germany should continue to focus on balancing deterrence and dia­logue, it seems necessary to prioritise the former in the short and medium term. For this reason, Berlin should not only play an active role in reassuring NATO’s frontline states and in the recently adopted reposi­tioning of the alliance, but it should also continue to strengthen Ukraine’s resilience.