Russia’s invasion of Ukraine in February 2022 and the nuclear threats it has made since have driven a new wave of militarization in Europe. In addition to pushing Finland and Sweden to seek membership in NATO, the perception of an increasingly unpredictable and revanchist Russia has led the alliance to boost its deterrence capabilities. These efforts have focused mainly on conventional forces, but arguments are currently also being made for strengthening nuclear deterrence.
The loudest calls are coming from Poland, whose leaders have indicated that their country would like to host nuclear weapons from the United States. More specifically, Poland would like to enter NATO’s ‘nuclear sharing’ arrangements, thus joining Belgium, Germany, Italy, the Netherlands and Türkiye, which host US non-strategic B-61 nuclear bombs and operate dual-capable aircraft (DCA) that can carry them. While Polish interest in nuclear sharing predates February 2022, it has received more serious consideration since the invasion and the March 2023 announcement by Russia that it, too, would engage in nuclear sharing with Belarus, where it claims to have already deployed nuclear weapons. Other proposals being discussed include developing and deploying new types of nuclear weapon and increasing the capacity of US non-strategic nuclear weapons in Europe to survive a counterforce attack by dispersing them across a greater number of locations during crises.
This essay takes issue with such proposals, arguing that NATO has no need to augment its already superior conventional forces by increasing reliance on weapons of mass destruction. While sufficient defensive forces are needed especially at the alliance’s eastern borders—which have in fact been strengthened by NATO’s Nordic enlargement—Europeans should avoid excess in the nuclear domain in order to avoid escalation and arms race dynamics and to promote long-term solutions to the continent’s security challenges.
The original rationale behind US non-strategic nuclear weapons in Europe
Non-strategic nuclear weapons were initially deployed in Europe in the 1950s to offset Soviet superiority in conventional military power and to assure allies of the USA’s commitment to their defence. In contrast to strategic weapons—which are directed at high-value targets deep inside an adversary’s territory—non-strategic weapons are designed to be used tactically on the battlefield or in the theatre of war; hence they are sometimes also called ‘tactical’ or ‘theatre’ nuclear weapons. Reflecting the Soviet/Russian–US relationship, these weapons are often distinguished from strategic ones based on their shorter range, even though this definition is not applicable to other nuclear-armed states that are in close geographical proximity to their adversaries. Although, locally, these weapons could unleash horrors similar to or worse than those experienced in Hiroshima and Nagasaki in 1945, in the cold war non-strategic nuclear weapons were seen as providing options for ‘limited’ nuclear weapon use that might not lead to world-ending global nuclear apocalypse involving the strategic forces on both sides.
NATO strategists argued that by lowering the threshold for nuclear weapon use in this way, non-strategic nuclear weapons would make the alliance’s deterrent threats more credible and thus potentially more effective in preventing Soviet conventional aggression. At the same time, the underlying logic of escalation control assumed that if NATO were to use non-strategic nuclear weapons, either the Soviet Union would be deterred from responding in kind or the resulting nuclear war could be limited and even won. Reflecting the shift in the balance of power in Europe after the cold war, indications of the same logic began to appear in Russian military doctrine and debates in the 2000s.
Yet this escalation control logic rests on shaky foundations. The assumptions that the first use of a nuclear weapon would not necessarily trigger a nuclear response and that a nuclear war could indeed remain limited have always been questionable. Moreover, as highlighted by recent research, the humanitarian and environmental effects of nuclear weapons cannot be contained by national borders, and even a regional nuclear exchange could have devastating global effects by creating a nuclear winter.
Non-strategic nuclear weapons as tools of assurance
When the conventional balance of power shifted in favour of NATO following the end of the cold war, US nuclear weapons in Europe all but lost their military relevance. In line with the Presidential Nuclear Initiatives in 1991 and through a decision of the NATO Nuclear Planning Group that same year, the number of non-strategic nuclear weapons that the USA deployed on the continent was cut from thousands to hundreds; only the air-deliverable B-61 bombs remained, while other non-strategic weapons were removed and eliminated by the USA. Two former hosts of these weapons, Greece and the United Kingdom, eventually ended their participation in nuclear sharing and high-level officials in the German leadership proposed doing the same. However, the B-61 bombs—whose number is currently estimated at around 100—remained in Europe largely because of the symbolic value of nuclear sharing in embodying the transatlantic bond. Moreover, particularly after the 2010 NATO Strategic Concept, allied statements linked further reductions in this category to the need for reciprocal measures by Russia, whose arsenal of non-strategic weapons is much larger than that of the USA.
The symbolic importance of nuclear sharing was further highlighted by Russia’s 2014 annexation of Crimea and its full-scale invasion of Ukraine in 2022. In this context of heightened European anxiety, the modernization of B-61 bombs and their delivery vehicles—which include advanced F-35 aircraft—gained new urgency, while the previously low-profile annual exercise simulating the use of these weapons was given more visibility. Although the current situation has increased the role of non-strategic nuclear weapons as a means of reassuring the USA’s European allies, it has hardly created a new military rationale for these weapons.
Deterrence works, but not thanks to B-61 bombs
The war in Ukraine has been deeply shocking for Europeans but it does not indicate a failure of deterrence on NATO’s part. On the contrary, Russia’s invasion of Ukraine seems to have been motivated by the fear of ‘losing’ Ukraine to NATO. The prospect of further NATO enlargement into Russia’s self-identified sphere of influence dominates Russia’s threat perceptions and was visible in its leadership’s justifications for the war.
The most significant source of NATO’s deterrent power is the combination of political unity and the advanced conventional forces that the allies can mobilize for collective defence during a crisis. NATO was already superior to Russia in terms of its conventional forces before 2022, but its relative strength has subsequently grown with the shift towards ‘forward defence’ and the recent wave of Nordic enlargement. These developments strengthen deterrence, particularly in the Baltic, which has been deemed as the most likely location of a potential fait accompli, whereby Russia would use its local military advantage to quickly seize territory before the mobilization of allied forces. Moreover, the war in Ukraine has not only expended vast Russian conventional resources but also demonstrated that Russia’s precision-strike weapons are not as advanced as previously assumed.
Additionally, Russia is deterred by the huge arsenal of US strategic nuclear forces—nuclear-armed submarines, long-range strategic bombers and intercontinental missiles—which hold Russia under existential threat at all times. These weapons form the backbone of the ‘extended nuclear deterrence’ under NATO. US strategic forces also include limited options for tactical nuclear strikes in line with the logic of escalation control; in addition to strategic bombers that can deliver B-61 bombs without the need to consult allies, the USA deploys low-yield W76-2 warheads on its strategic submarines. Since 2022, the USA has intensified nuclear signalling related to these forces, including through increased overflights and landings of strategic bombers in allied territory, sometimes very close to the Russian border.
In contrast to NATO’s conventional power and the USA’s strategic nuclear forces, the US non-strategic nuclear weapons under NATO nuclear sharing arrangements do not constitute a credible means of deterrence. Although the replacement of older DCA with F-35s increases the likelihood of penetrating the adversary’s air defences in the case of a NATO nuclear strike against Belarus or Russia, a decision to do so would require not only authorization by the US and UK heads of state but also consensus among the alliance’s Nuclear Planning Group. This would mean an unlikely agreement among a group of 30 European democracies to order the first use of nuclear weapons or to respond in kind to a nuclear strike, thus engaging in nuclear warfare. Even if the allies could reach such a decision, any effort by NATO to control escalation would be undermined by the vulnerability of allied air bases to Russian counterforce attacks. Russia has thousands of nuclear weapons that it could use to destroy these bases, even after successful NATO strikes on Russian territory.
The expansion of the existing nuclear sharing model to include new countries therefore makes little sense as a means to strengthen deterrence. Apart from further fuelling tensions, a new nuclear weapon base in Poland would add one more location to the adversary’s list of targets during a potential nuclear war. Insofar as US nuclear weapons in Poland would contribute to deterrence, this would have little to do with the weapons themselves and would rather derive from the American boots on the ground that would come with the B-61 package.
Addressing the survivability problem through dispersal
Reflecting a partial recognition of the credibility problem described above, discussions are happening behind closed doors within NATO on ways to increase the survivability of non-strategic nuclear forces. The debate seems to be focused on a ‘dispersal’ strategy, whereby US non-strategic nuclear forces would be spread across a greater number of European locations during crises, thereby complicating counterforce targeting for the adversary.
An IISS report from September this year also discusses the idea. As a more viable alternative to peacetime nuclear weapon deployments in Poland, it suggests that NATO could ‘designate several Polish airfields as potential Dispersed Operating Bases’ to provide ‘additional options for dispersing dual-capable aircraft in wartime and in near-war situations’. It further suggests that, even if Poland did not host B-61 bombs, the Polish F-35s could be certified to deliver such weapons, and that similar measures could be taken in other member states. Until now, only those US allies that host nuclear weapons have been authorized to operate DCA under NATO nuclear sharing arrangements.
There are indications that some elements of a dispersal strategy are already being implemented in the UK, which maintains a national sea-based strategic nuclear deterrent but does not possess non-strategic nuclear weapons of its own. As reported by the Federation of American Scientists, US Air Force budgetary documents imply that, 15 years after the withdrawal of US non-strategic nuclear weapons from the UK, the nuclear weapon storage facility at RAF Lakenheath airbase is being upgraded. Noting denials by US officials of plans to redeploy US nuclear weapons on UK soil, the FAS report notes that the base could ‘potentially receive nuclear weapons in the future or in the midst of a crisis, without necessarily having already decided to permanently station them’. The report also points to construction projects at other hosting states’ nuclear weapon bases that are ‘designed to facilitate the rapid movement of weapons on- and off-base to increase operational flexibility’.
Depending on the extent to which it is implemented, the dispersal strategy would indeed complicate targeting for the adversary by creating uncertainty about the location of NATO nuclear forces. However, in practice Russia can be expected to hedge against this uncertainty by expanding the list of European targets during a hypothetical nuclear war to also include potential rather than just known nuclear weapon facilities, thereby exposing a bigger portion of the European continent to the devastating effects of nuclear explosions. Moreover, dispersal does not remove the main factor undermining the credibility of NATO’s non-strategic nuclear threats, which is that a large group of European democracies can hardly be expected to take a unanimous decision to turn their continent into a theatre of nuclear war.
Calls for new nuclear weapons in Europe
In recent years, several commentators have argued for the reintroduction of land-based intermediate-range missiles to Europe. These sub-strategic weapons—with a range of 500–5500 kilometres and thus seen as halfway between non-strategic and strategic weapons—were banned by the 1987 Intermediate-Range Nuclear Forces (INF) Treaty, from which both Russia and the USA withdrew in 2019. Noting that the treaty only came about after NATO’s 1983 deployment of nuclear-armed intermediate-range missiles, which was a response to earlier Soviet SS-20 deployments, proponents argue that a similar move today could push Russia to the arms control table.
However, this historical analogy hardly stands up to scrutiny. The INF Treaty was the result of several fortunate conditions that happened to align at the time. These included the personalities of the Soviet and US leaders, their shared ambition to pursue nuclear disarmament, and the perception of symmetry in intermediate-range capabilities, creating a mutual interest in their elimination. The prospects of recreating such circumstances today are slim. Instead, a more likely result of European intermediate-range missile deployments would be a reciprocal Russian response, which would further worsen regional arms race dynamics. Even if armed with conventional warheads, as some have proposed, intermediate-range missiles involve particular escalation risks due to the combination of their ability to strike deep into an adversary’s territory and the difficulty of distinguishing between nuclear and conventional warheads during a crisis.
A more authoritative proposal for new nuclear weapons in Europe, the October report by the Congressional Commission on the Strategic Posture of the USA, recommends additional theatre nuclear capabilities in Europe that are ‘deployable, survivable, and variable in their available yield options’. Although the authors are not explicit about what weapon types they have in mind, recent US debates suggest that these could include land-based intermediate-range missiles and nuclear-armed sea-launched cruise missiles (SLCM-N).
Unlike the dispersal strategy, which would not involve changes in peacetime nuclear weapon deployments and might therefore not provoke major public reaction, nuclear force build-up involving new nuclear weapons would be a hard sell in Europe. This is especially true if new land-based missiles were to be introduced to the continent. Deployment of SLCM-Ns on US attack submarines would be less visible and thus also less controversial among allied countries. It would nevertheless pose a challenge for US relations and military cooperation with those NATO members (such as Denmark and Norway) that do not allow the transit of nuclear weapons through their territory or visits by nuclear-armed vessels at their ports. As US critics point out, SLCM-Ns, if deployed, would also increase escalation risks and worsen arms race dynamics by triggering responses from US adversaries. Moreover, given that the US strategic arsenal already provides options for tactical nuclear weapon use, it is hard to see the added deterrence value of the proposed new theatre nuclear weapon deployments.
The need for a long-term perspective on European security
Despite NATO’s military superiority over Russia, a feeling of insecurity persists in Europe, which can make analysts and government officials receptive to proposals to increase reliance on nuclear weapons. In addition to Russia’s actions in Ukraine, this can partly be explained by the nature of conventional deterrence. While there is no doubt that nuclear threats, if carried out, would lead to unacceptable damage to the adversary, the effects of using conventional force are more difficult to predict. This is because the ability to wage a conventional war depends not only on military capabilities but also on other factors such as strategy, tactics and morale. Moreover, information on the existing conventional forces is scattered and not easily available, which complicates comparative assessments and arguably contributes to the tendency to underestimate NATO’s relative power compared to Russia.
Another factor highlighting the sense of insecurity in Europe is that Russian nuclear threats have exposed Europe’s vulnerability to nuclear weapons for the first time since the end of cold war. US strategic signalling and plans to strengthen NATO’s non-strategic nuclear forces have reassured its European allies, but they have also contributed to the illusion that Europe’s vulnerability to Russian nuclear weapons could somehow be reduced by greater investment in nuclear deterrence. In reality, as suggested above, the strategy of dispersing nuclear weapons during crises would only make nuclear war in Europe more devastating, while deploying new nuclear weapons could make such a war more likely.
Instead of a futile quest for absolute security, Europeans should recognize the strength of NATO’s existing conventional forces, which can temper worst-case assumptions about Russian aggression against NATO. The downside to the prevailing power imbalance in Europe’s favour is that Russia will likely continue its greater reliance on nuclear weapons while it rebuilds its conventional forces. There is, however, no military solution to this problem. Ultimately, threat perceptions on both sides need to be addressed through the creation of a more sustainable regional security order that not only ensures sovereignty for Ukraine and other countries that might fall victim to Russian aggression but also reduces Russia’s exaggerated threat perceptions of NATO. While this seems unachievable under the current Russian leadership, tensions could be managed in the short term by promoting stability at the NATO–Russian border. Norway’s longstanding self-imposed restrictions on allied overflights and military exercises in its northern territory near the Kola Peninsula provide one model that could be extended to NATO’s new Nordic members—notably Finland, whose more permissive policy on allied overflights may undermine the Norwegian restrictions.
As for nuclear risks in Europe, the only way to escape them is for nuclear-armed adversaries to reduce their mutual tensions and, ultimately, engage in arms control and nuclear disarmament. Therefore, promoting arms control between Russia and the USA is key to European security. European NATO allies should also do their part by seeking to reduce reliance on nuclear weapons for deterrence, starting with non-strategic nuclear weapons. Threats based on the latter lack both credibility and a convincing military rationale. This means NATO could move towards a policy of no first use and end nuclear sharing with no real impact on deterrence. While not politically feasible at the moment, such steps would not only promote regional security in Europe but also help to counter the dangerous global trend whereby nuclear weapons are viewed as a panacea for complex security dilemmas.
