Reducing Global Reliance on Nuclear Deterrence

The 80th anniversary of the atomic bombings of Hiroshima and Nagasaki in 2025, and the awarding of the 2024 Nobel Peace Prize to Nihon Hidankyo – the grassroots movement of atomic bomb survivors of these two attacks – as well as increased tension between nuclear-armed states, have brought additional attention to the question of whether there can be realistic pathways to reduce reliance on nuclear weapons and pursue nuclear disarmament. 

This paper summarises the results of a project between RUSI and the Hiroshima Organization for Global Peace (HOPe), and examines pathways for reducing the roles and functions of nuclear weapons. 

The main research question for this paper concerns the most realistic approach to changing the policy of the possessors of nuclear weapons, as well as the countries which rely on extended nuclear deterrence guarantees, including US allies in the Euro-Atlantic and Indo-Pacific regions. While conclusions regarding the potential reduction of the salience of nuclear weapons apply to all possessors, they may be most relevant to policymakers and strategic communities in Western states, as they are the most open to discussing changes in the nuclear posture. 

The analysis in this paper focuses on ‘down-sizing’ or ‘right-sizing’ nuclear deterrence as perhaps the most realistic first step in the gradual narrowing of the role played by nuclear weapons. The main aim of this paper is to investigate options to ‘further diminish the role and significance of nuclear weapons in all military and security concepts, doctrines and policies’, as pledged in the 2010 Final Document of the NPT (Treaty on the Non-Proliferation of Nuclear Weapons) Review Conference. This approach may contribute to the goal of moving towards nuclear disarmament. Reducing the role of nuclear weapons could be achieved through nuclear possessors phasing out, rather than decisively rejecting, reliance on them. While external pressure can play a role, decision-makers in nuclear states will need to be persuaded that a comparable sense of security can be achieved with lesser reliance on nuclear weapons. 

Such an approach would be conceptually distinct from devaluing and delegitimising nuclear weapons, which constitutes an overall rejection of the value of nuclear weapons and nuclear deterrence, stemming from arguments about illegality of the possession and any use of nuclear weapons – as exemplified by the Treaty on the Prohibition of Nuclear Weapons and analyses challenging the nuclear deterrence construct.

Methodology 

In the context of the project ‘Envisioning global security without reliance on nuclear deterrence’, RUSI and HOPe convened three online working group meetings between 2023 and 2025, covering the Indo-Pacific, Euro-Atlantic and Middle East regions, and a conference held in Hiroshima in June 2024. The purpose of these meetings was to gather preliminary thoughts from participants on three key questions:  

1. What functions do nuclear weapons currently serve in regional security contexts?
2. What alternatives are available that could fulfil these functions?
3. To what extent is reducing the role of nuclear weapons in states’ security policies possible and, meanwhile, which interim steps for these states are realistic? 

Participants in this research and in subsequent interviews included non-governmental experts from nuclear-armed states (except North Korea), and from a number of countries in Europe and the Indo-Pacific which are covered by nuclear extended deterrence guarantees in the framework of US-led military alliances, as well as participants from the Middle East. 

The paper also draws on strategic documents from nuclear-armed and nuclear-umbrella states (especially nuclear doctrines, policy reviews and summit communiques), as well as on statements from relevant decision-makers. Finally, it builds on the literature and expert debates on nuclear deterrence, nuclear restraint and risk reduction, as well as bilateral/regional nuclear arms race dynamics. 

Background

The international situation is not conducive to reducing the role of nuclear weapons. In fact, the salience of nuclear weapons – that is, their importance in the doctrines and practices of nuclear-armed states – has been increasing in the Euro-Atlantic and Indo-Pacific regions. Russia’s full-scale invasion of Ukraine, its nuclear signalling and attempts at nuclear intimidation, its doctrinal changes and its continuation of nuclear modernisation point to the significant role played by nuclear weapons in Russia’s security strategy. In 2022, Russia and Belarus reached an agreement on nuclear sharing, which could see the deployment of Russian nuclear weapons in Belarus. North Korean nuclear modernisation and brinkmanship and China’s reported major build-up of nuclear forces have increased the salience of nuclear weapons in Asia. In South Asia, following the Pahalgam terrorist attack, nuclear-armed India and Pakistan fought a short but intense conflict in May 2025 which was conducted under a nuclear shadow, albeit without reaching the point of nuclear escalation.

The importance of nuclear weapons in the regional context of the Middle East has so far remained constrained by Israel’s policy of nuclear opacity, but the threat of nuclear proliferation remains, and is primarily connected with the progress of the Iranian nuclear programme. Indeed, the Middle East has recently gone through a major escalation of tensions and military conflicts, including in June 2025 when Israel and the US launched attacks against Iran, including its nuclear infrastructure. The potential acquisition of nuclear weapons by Iran would increase the pressures towards further nuclear proliferation in the region.

In response to Russia’s actions, NATO members have been bolstering the credibility of Allied nuclear deterrence posture. Asian allies and partners of the US have continued to rely on American extended nuclear deterrence guarantees and strengthened deterrence dialogues with the US. Meanwhile, the presidency of Donald Trump has brought additional challenges to these extended deterrence relationships, as it spurred discussions about the credibility of US nuclear guarantees and the potential that nuclear proliferation could result in US allies acquiring nuclear weapons, thereby further increasing their global salience.

In the absence of strategic arms control talks, and with the upcoming expiration of the New START treaty in February 2026, the prospect of increases in the US and Russian nuclear arsenals looms, with consequences beyond these two countries. Despite President Trump’s declarations of his preference for nuclear reductions and Russia’s offer to prolong voluntary adherence to the main limits of the New START treaty for one year after February 2026, there have been no bilateral or multilateral negotiations on the subject (as of November 2025). President Trump’s October 2025 (albeit vague) announcement regarding the resumption of nuclear testing and the likely reactions from Russia and potentially China in terms of matching the US may lead to a further increase in the salience of nuclear weapons. 

Of course, reliance on nuclear deterrence is not a universal phenomenon. Beyond the commitments of non-nuclear-weapon states under the NPT, the 74 states party to the Treaty on the Prohibition of Nuclear Weapons have also rejected development, possession, threat or use of nuclear weapons, in practice moving further than the NPT in discarding nuclear deterrence, and extended nuclear deterrence, as tools of policy. The same rejection of acquisition and possession of nuclear weapons applies to the countries forming regional nuclear weapons-free zones. The example of South Africa demonstrated that possession of nuclear weapons can be reversed through political decisions. 

Contemporary Roles of Nuclear Weapons 

Doctrines of nuclear-armed states stipulate or at least generically describe the circumstances in which nuclear weapons could be used. While these doctrines may leave space for deliberate ambiguity with regard to the actual circumstances of use, they provide indications to not only potential opponents but also allies and other international actors of the conditions and modalities of nuclear employment. They therefore remain the principal reference point for reflections about reducing the role of nuclear weapons. This section presents the deterrence roles of nuclear weapons and their importance as tools for maintaining regional and global influence.

Figure 1: Global Nuclear Warhead Stockpiles, 2025

Source: Hans M Kristensen et al., ‘Status of World Nuclear Forces’, Federation of American Scientists, 26 March 2025.

A distinction can be made between the core or primary function of nuclear weapons – namely, to deter a nuclear attack and safeguard the very survival of the state – and other functions, which can be seen as second-tier roles.

Regarding the primary function, nuclear-armed states declare their readiness to use nuclear weapons in extreme circumstances of self-defence, most fundamentally in response to a nuclear attack, and also (in relevant instances) to provide extended nuclear deterrence for allies and partners in case of a nuclear attack against them. 

Concerning the second-tier roles, nuclear doctrines and postures of possessors vary significantly, but in many cases the role of nuclear weapons includes: 

• addressing the threat from biological and chemical weapons and from major conventional attacks;
• providing extended deterrence and Alliance reassurance against non-nuclear attacks; and
• limiting damage or terminating conflicts on acceptable terms if nuclear deterrence fails, especially through the deployment of capabilities and formulation of plans to target the adversary’s nuclear forces. 

For some countries, nuclear weapons also seem to enable possessors to engage in strategic coercion and intimidation under a nuclear shadow. At the other end of the spectrum, China and India have adopted ‘no-first-use’ policies, which they argue could serve as the blueprint for other nuclear-armed states’ nuclear policy and doctrine development.

Further extension of the role of nuclear weapons remains a possibility. Political and expert discourses in recent years in a number of nuclear-weapon states have focused on the alleged vulnerabilities or inadequacy of existing nuclear postures in the new strategic environment – and thus on the need to address doctrinal or capability gaps by enlarging the scope of nuclear deterrence or by increasing the size or composition of nuclear forces. In the case of Russia, this has resulted in a revised nuclear doctrine, which broadens the list of conditions which may lead to nuclear employment, including a massive conventional airspace attack. In the US, the projections regarding the development of the Chinese nuclear arsenal and the emergence of the strategic environment of the ‘two nuclear peers’ (in which the US would need to simultaneously deter Russia and China and plan for the scenario of being confronted by enemies with increased numbers of nuclear weapons) has driven proposals for an increase in the size of the US nuclear arsenal and the development of additional non-strategic nuclear capabilities for regional contingencies.

The ownership of nuclear weapons may also confer international status and prestige to a state, especially considering the possession of nuclear weapons by the five Permanent Members of the UN Security Council. These weapons can serve as instruments to enhance national standing and a particular leader’s profile, demonstrating strategic importance and technological advancement. The role of nuclear weapons as visible guarantors of regime survival is crucial in the case of totalitarian states – such as North Korea – and authoritarian possessors. 

Nuclear weapons continue to play an important role in affecting regional and cross-regional strategic stability. The interconnectedness of security and threat perceptions within and across different regions further affects the national perceptions of salience of nuclear weapons. While US attention tends to focus on the trilateral relationship between the US, Russia and China, the nuclear deterrence landscape has become increasingly multipolar and complex: other nuclear-armed states react to developments such as quantitative or qualitative increases in nuclear stockpiles or doctrinal changes in these three states with adjustments of their own. For example, changes in Russia’s nuclear and missile defence posture have partly shaped perceptions of nuclear deterrence requirements of the UK and France. India’s nuclear modernisation and posture has been primarily influenced by Pakistan but also takes into account China’s modernisation. 

It is also worth adding that nuclear weapons possessors’ formal nuclear doctrines and their understanding of the role of their nuclear forces often differ significantly from the perceptions and interpretations of their adversaries. Nuclear doctrines are usually seen from the outside as more extensive in scope or with lower nuclear use thresholds than the ones declared. This further diminishes the likelihood for the potential reduction of the role of nuclear weapons, as it justifies maintaining nuclear deterrence capabilities addressing the perceived threat. Most notably, Russian and Chinese officials perceive the US nuclear strategy as being aimed at gaining nuclear primacy, which would offer the US the option of a disarming first strike against their nuclear forces, in spite of the US not pursuing such policy. Also, as described above, China has a no-first-use policy but external experts question its credibility and relevance. Finally, there are worries in the West that the threshold of nuclear weapon use by Russia could be lower that its public doctrinal one, especially regarding the use of sub-strategic nuclear weapons in regional scenarios involving conventional warfare. 

Approaches to Reducing the Political and Doctrinal Salience of Nuclear Weapons 

As described above, the functions of nuclear weapons remain diverse and embedded into broader adversarial relationships between possessors, so reductions would be dependent on addressing all aspects of nuclear weapons’ importance. 

Historically, the reduction of tension between nuclear-armed states has led to a limitation of the roles of the weapons and a reduction in their numbers, including through bilateral arms control arrangements in the final stages and in the aftermath of the Cold War, and through related unilateral reductions. However, the conditions for these reductions could not be easily replicated. Even if a cessation of current conflicts involving nuclear-armed states and their allies and partners could be achieved, it may not necessarily result in diminishing the salience of nuclear weapons. An overall easing of international tensions, a lasting resolution of ongoing disputes and the adoption of cooperative global and regional security arrangements could radically change the attitude towards the value of nuclear deterrence and create movement towards nuclear disarmament.

While nuclear weapons will probably continue to serve their primary function – to deter a nuclear attack and safeguard the very survival of the state – the second-tier functions could be partially or fully substituted by other means, thus offering a path towards nuclear reductions. Starting with the political and doctrinal aspects, this chapter suggests the avenues which could be used to narrow the functions of nuclear weapons in national strategies.

A variety of political, but also symbolic and psychological, functions for nuclear weapons first need to be addressed. These functions are rarely mentioned explicitly by possessor states as part of their formal security doctrines and therefore remain in the background. With respect to bolstering international status and prestige, states could explore relying on other sources of national power, including economic factors, standing within international organisations, technological advances and/or indicators of societal development. Changing international attitudes towards the possession of nuclear weapons can also play a role. If reductions of nuclear weapons’ salience are welcomed by the international community and global public opinion as a stabilising move, a state and its leadership could draw increased legitimacy from taking decisions in that direction. Strengthening the taboo against nuclear use can therefore help reduce their value, aided by declarations such as statements made by the five nuclear-weapon states (P5) and the G20 about the inadmissibility of nuclear war. 

For the states that envisage a broader set of circumstances in which nuclear weapons could be used, one potential pathway for reducing the doctrinal salience of nuclear weapons is to move towards a ‘sole purpose’ formula – that is, a stipulation that the only role of nuclear weapons would be to deter nuclear use against this country or its allies, ‘reflecting the reality that they are weapons of extreme last resort’. A more radical solution would be to follow China and India’s adoption of a no-first-use pledge; however, there may be questions about the credibility and impact of making such a pledge without parallel and adequate changes in the nuclear posture of the states adopting such policy. More gradual doctrinal changes, which could complement a reduced role of nuclear weapons in favour of conventional substitutes, would either need to include explicit narrowing of the conditions for the use of nuclear weapons, or leave the circumstances of using nuclear weapons open-ended, while shaping nuclear posture and development of nuclear capabilities in a way that would keep them optimal to ensure core deterrence function only.

Moving towards sole purpose or no-first-use policies may bring additional doctrinal challenges connected with extended deterrence relationships. In the case of countries providing extended nuclear deterrence (such as the US and UK for NATO Allies, and Russia for Belarus and its Collective Security Treaty allies), decisions in their doctrines to reduce reliance on nuclear weapons and potentially phase out some of the systems designed for regional and theatre-level deterrence may be seen by their partners as a sign of weakened overall resolve to defend them. Reducing the role of nuclear weapons in alliance settings would thus need to be accompanied by other measures which would strengthen deterrence and increase alliance cohesion, such as changes to conventional military alliance posture through reinforced forward deployments, or joint investments in non-nuclear weapon systems. Symbolic actions such as reconfirmation of political guarantees would probably also be needed, to reassure allies and partners of the strength of the extended deterrence relationship.

Increasing the Role of Non-Nuclear Capabilities

Limiting the role of nuclear weapons and replacing them with non-nuclear military capabilities, as outlined in this section, could in fact increase the deterrence credibility against specific types of attacks. This result is conceivable if the opponents were to consider such use of non-nuclear capabilities as equally as credible as, or more credible than, the use of nuclear capabilities, and destructive or disruptive enough to lead them to reconsider a particular aggressive course of action. In addition, non-nuclear responses are more likely to secure compliance with international humanitarian law than nuclear use. This section argues that conventional capabilities can replace nuclear weapons in deterring conventional attacks, threats from other WMDs, and other non-nuclear strategic attacks, as well as contribute to the deterrence of nuclear attacks. 

The threat of the employment of conventional capabilities may not be enough to replicate the psychological dimension of the threat of nuclear weapons, nor the ability to inflict widespread and unacceptable damage. There exists, however, a range of emerging and existing military capabilities – characterised by increased precision, speed, lethality and destructive power, extensive ranges, and flexibility and promptness of use – which could replace nuclear weapons in specific scenarios, especially if paired with robust command and control (C2) and ISR capabilities.

These capabilities include: 

• long-range precision strike weapons, such as conventional-armed missile systems and long-range attack drones;
• tailored use of other conventional forces, including airpower;
• offensive cyber capabilities;
• space and counter-space capabilities; and
• air and missile defence systems. 

While attention has been mostly focused on strike capabilities, defensive systems – including air and missile defence, and other systems designed to limit the likelihood of the success of an initial attack – would also contribute to the credibility of a non-nuclear, conventional deterrence posture. Other non-nuclear deterrence by denial options could comprise tailoring forward defence postures (including deployment of forces and border fortification), increasing civil defence and societal preparedness, and working on readiness and resilience.

Developed in a systemic manner, all these conventional capabilities could provide substitution for the secondary roles fulfilled by nuclear weapons, including responding to non-nuclear strategic attacks, deterring and responding to the use of other WMDs (including neutralisation of biological or chemical weapon stockpiles), and responding to any other large-scale conventional attacks or high consequence attacks.

For a non-nuclear deterrence posture to successfully affect the strategic calculus of an adversary, it would need to be accompanied by an employment doctrine which would include a broad targeting set. Demonstrating the capability to disrupt military operations at scale and deliver considerable damage to the military potential and war-supporting segments of the adversary’s economy, and targeting the adversary’s C2 centres, could have a required deterrent effect. The threat that conventional rather than nuclear weapon systems would be employed may affect the adversary’s perception of their usability and thus reinforce the credibility of deterrence signalling. To achieve this effect, the scale of the threatened non-nuclear response, the capacity to overcome adversarial defences, and the ability to subsequently continue to conduct operations would need to be on a scale which would decisively affect the adversary’s calculus. This could involve introducing a variety of systems with different combat characteristics, allowing the state to reach targets at the operational and strategic depth levels. The level of capabilities required to deter adversaries can be determined by the ability to strike not only military targets but also crucial elements of the adversary’s infrastructure which support military operations, the defence industry and other sectors of the economy supporting the war effort.

Although it is supported by US extended deterrence, South Korea’s three-axis deterrence system could offer one example of a sophisticated conventional deterrence posture which can successfully create leverage against a nuclear-armed adversary (in this case, North Korea). The posture includes offensive and defensive weapon systems, including deep precision strike systems, air and missile defence, cyber operations capabilities and use of special operations assets, paired with networked intelligence, surveillance and reconnaissance capabilities and C2 arrangements. These systems are conceptualised as forming three main segments of the South Korean military strategy: finding and destroying North Korean missile launchers and nuclear storage; deploying the Korea Air and Missile Defense System; and implementing the Korea Massive Punishment and Retaliation plan against adversary regime targets, including North Korea’s leadership. 

Another example of non-nuclear deterrence signalling is when the US reportedly threatened Russia with ‘catastrophic consequences’ to address the risk of low-yield nuclear weapons use by Russia against Ukraine in late 2022. These consequences were broadly understood to be an overwhelming conventional response by the US and, potentially, by a group of its partners. This illustrates the role which conventional weapons may hold in deterring a limited nuclear use. For such a deterrent threat to be effective, conventional forces would need to be seen as capable of inflicting sufficient damage as to make the costs of nuclear use too high. In this instance, the US signalling served to mitigate the threat of Russia initiating limited nuclear use against Ukraine in the first place. 

Regarding other types of potential attacks, the premise that chemical attacks need to be effectively deterred with a threat of nuclear response arguably lacks credibility. The threat of responding to a single chemical attack – which would probably have caused limited damage and casualties – with nuclear use could be seen as disproportional and thus implausible, and therefore would not constitute a reliable deterrent. In contrast, the threat of a non-nuclear response can be used as a deterrent aimed at the level of the unit responsible for a chemical attack, or up the chain of command, to target the military and civilian leadership responsible. The threat of conventional attacks targeting stockpiles and production facilities for chemical weapons could also be signalled.

Deterrence of non-nuclear but ‘high consequence, strategic-level attacks’ – for example, the use of biological weapons, massive cyberattacks, or sabotage or destruction of crucial elements of a country’s critical infrastructure – can also probably be better achieved through the threat of an overwhelming conventional and non-kinetic response. Deterrence by punishment could be combined with strengthening deterrence by denial and resistance capacity, thereby negating or limiting the damage caused by such attacks.

In sum, existing and emerging non-nuclear capabilities can offer tools for crafting a credible deterrence posture that can respond to a range of scenarios.

Pathways Towards Reducing Nuclear Risks 

In parallel with developing non-nuclear deterrence postures, there is a continuous need to invest in measures to stabilise the antagonistic relations between nuclear possessors and reduce the likelihood of accidental or inadvertent escalation of any conflict to the nuclear level. Such measures can be applied to both nuclear and non-nuclear weapon systems.

The role of nuclear weapons in the security doctrines of the possessors, and their decisions related to nuclear posture development, are related to the threat assessment and state of the adversarial relationship between the nuclear states. The salience of nuclear weapons is unlikely to diminish during a period of high political and military tensions between possessors, pointing to the need to explore risk reduction and confidence-building measures as measures of stabilising the relationship. The relationship between the US and Russia remains the most important one in this regard, due to the size and diversity of their arsenals. One basic risk reduction measure would be to return to the strategic stability talks between the two countries, which could lead to establishing a better mutual understanding regarding the relationship between nuclear and non-nuclear weapon systems (including missile defence assets). It could also lead to identifying potential arms control approaches to the nuclear and strategic conventional systems. Political and expert dialogue between China and the US could include discussions on nuclear doctrines, nuclear balance of forces, conventional balance of forces and escalation potential in the Indo-Pacific. 

Specific risk-reduction measures connected to the threat of accidental or inadvertent escalation to the nuclear level could include the exchange of information connected to stockpile sizes, and briefings and discussions regarding the modernisation plans for major categories of systems such as long-range missiles, as well as assuring effective crisis communication channels. States could participate in voluntary restraint measures in terms of deployment areas and numerical limits on deployments of particular conventional systems. New, formal conventional arms control regimes could include numerical ceilings for specific categories of systems such as long-range missiles or drones, accompanied by verification measures. However, such arrangements may be challenging to reach, as they would need to strike an equilibrium which would, on the one hand, fulfil the deterrence and defence requirements for each side – especially in a multilateral regional strategic environment in the Euro-Atlantic or Indo-Pacific region – and on the other hand, meaningfully reduce the likelihood of war. 

Another challenge in establishing risk reduction measures for non-nuclear, conventional strategic systems concerns the necessity of non-nuclear capabilities to be able to inflict adequate damage on the adversary to increase their deterrence effect. This would inherently limit the scope for transparency and confidence-building measures, as states would be worried that providing extensive information on weapon systems, deployments and planning would allow them to be targeted or neutralised pre-emptively or early during the conflict. Considering the current trends towards the development and acquisition of strategic non-nuclear capabilities, and the fact that the experience of the Russia–Ukraine war points to the need to establish vast and diverse stockpiles of weapons and ammunition for a potential protracted conflict, establishing numerical restraints may not be possible in the short to medium term – at least until a point of saturation (the level at which the deterrence effect had been achieved), has been reached. 

Establishing a deterrence equilibrium with a reduced reliance on nuclear weapons and additional risk management measures would not in itself lead to nuclear disarmament but could result in some nuclear reductions. Nuclear weapons would remain as backstop capabilities in case of a nuclear attack, preserving a state’s ability to inflict unacceptable damage on its adversary without the need to engage in tactical nuclear use. States adopting such a posture would retain nuclear systems and command arrangements configured towards a credible second strike, planning for the survivability and reliability of their nuclear response as the main features. This posture would place a premium on capabilities tailored for second strike, such as strategic nuclear-armed and -powered submarines. The state would refrain from developing particular types of nuclear weapons (such as low-yield and short-range systems), thereby limiting the possibility of using nuclear weapons in other roles and scenarios.  

Potential Challenges and Opportunities 

Reducing the salience of nuclear weapons in the doctrines and postures of some possessors may bring additional challenges, which will be explored in this section. There would, however, also be opportunities in terms of creating additional space for non-nuclear allies in extended deterrence relationships to contribute to adopted deterrence postures. 

Responses from Adversaries

Creating the credible threat of a devastating conventional response could lead an adversary to conclude that the vulnerability of their nuclear forces has increased. They may even view a move towards increasingly non-nuclear deterrence posture as their adversary preparing for a non-nuclear disarming or decapitation strike against them. They may therefore make additional investments in nuclear capabilities, lower their nuclear use threshold and adopt decentralised C2 arrangements which may further increase the risk of nuclear use. To reduce the likelihood of such a response, states could shape their doctrine and signalling around the development of conventional strategic capabilities to highlight the limitations with regards to the categories of potential targets of strikes. They could for example pledge restraint – as far as possible considering the nuclear-conventional entanglement challenge – in terms of refraining from conventionally attacking targets connected with nuclear C2 and early warning and strategic nuclear forces. This could serve to alleviate some concerns that by limiting the role of nuclear weapons and investing in conventional capabilities, a state may be creating space to initiate and prevail in a conventional conflict, using the threat of use of its strategic nuclear forces to prevent the adversary from escalating to the nuclear level. 

The development of strategic missile defence systems would also have an impact on the adversaries’ responses. It may strengthen the conventional deterrence posture against both nuclear and non-nuclear capabilities of the adversary. However, it may also cause adversaries to look into diversifying their nuclear arsenals beyond ballistic missiles as a way to maintain the effectiveness of their nuclear capabilities. 

Alliance Management

If reliance on nuclear weapons were to decrease, the role of nuclear weapons in nuclear alliances would need to be re-evaluated, and the new overall deterrence posture would need to be synchronised with changes in the nuclear doctrines and capabilities of the nuclear-weapon states which act as the extended nuclear deterrence guarantors. The failure to reassure the countries covered by extended deterrence of the continued credibility and reliability of their protection, in the context of the reduced role of nuclear weapons, may create an alliance cohesion crisis. It could also lead to the covered countries potentially considering acquiring nuclear weapons, which may unintentionally result in nuclear proliferation. 

Developing conventional strategic capabilities may, however, also create opportunities for alliance management and adjusting internal burden-sharing. Resources of non-nuclear allies could be used to strengthen an alliance’s non-nuclear deterrence posture, through the acquisition and deployment of weapon systems tailored to increase the costs of aggression, especially conventional long-range strike weapons. Several such decisions have already been taken in the framework of US-led alliances. Examples include the procurement by Japan, Australia and the Netherlands of the US sea-launched Tomahawk cruise missiles, as well as Germany’s purchase of the Tomahawk’s land-based version. This approach has also been demonstrated through the development of collaborative initiatives for the acquisition of conventional versions of long-range strike systems, such as the European Long-Range Strike Approach – a project to develop missiles with a range of over 1,000 km – as well as the acquisition of air-launched standoff weapons by a number of US allies, such as Poland. National programmes which can contribute to Allied conventional deterrence posture, such as Denmark’s decision to acquire long-range strike systems, have indeed been justified in terms of their capability to strengthen deterrence. Similarly, investments in the development of both multilayered air and missile defence systems – such as the Korea Air and Missile Defense Systems or the European Sky Shield and other procurement initiatives – and regional early warning capabilities could serve to support a deterrence posture which would be less reliant on nuclear weapons. Taken together, these capabilities may provide an opportunity: by the early 2030s, a pool of assets could  be created to support a posture of stronger conventional deterrence in NATO and East Asia, potentially leading to a re-evaluation of the role of nuclear weapons. 

Political Leadership and Sequencing of Decisions

A move by any nuclear-armed state towards a less nuclear-centred deterrence posture may require strong and sustained political leadership, as well as public support, and would probably encounter internal resistance from proponents of maintaining the role of nuclear deterrence. Simultaneously, it may generate criticism from supporters of nuclear disarmament as being insufficient. Gradual change involving the introduction of non-nuclear capabilities and doctrinal announcements about the changing relationship between the two components would be a prudent measure. Nuclear weapons would remain a backup option until the credibility of a reshaped deterrence posture could be demonstrated, for example during a crisis. 

The drawback to a nuclear-armed state developing additional non-nuclear offensive and defensive deterrence options as a pathway to reducing its reliance on nuclear weapons may be the perception of the adversaries. As mentioned above, adversaries may view such changes as a preparation for a non-nuclear disarming or decapitation strike against them. This could put the conventionally superior nuclear-armed states in an advantageous position against countries which currently see nuclear weapons as instruments to address relative conventional weakness of forces and capabilities. (Examples of countries developing nuclear weapons to address conventional weaknesses include Pakistan versus India, Russia versus the US/NATO, and North Korea versus South Korea and the US.) This may push these adversaries towards increasing and diversifying their nuclear potential and developing doctrinal responses which may be destabilising, such as first- and early use of nuclear weapons or pre-delegation of launch authority. Therefore, if development of non-nuclear options were not accompanied by an overall easing of tensions, it may not lead to reciprocal reductions of the salience of nuclear weapons.

The primary movers for initiating change in nuclear postures may need to be the Western nuclear states, which could be more open than their nuclear adversaries to modifying their postures to maintain credible deterrence in relation to Russia and China, but with a reduced nuclear weapons footprint. This approach could be viewed as a manner of reducing the level of nuclear risks more broadly and contributing to the implementation of the NPT nuclear disarmament commitments. For instance, US doctrine could be modified to state that the deterrence of non-nuclear strategic threats would be implemented mostly through non-nuclear means, and that regional deterrence posture in the Euro-Atlantic and Indo-Pacific would rely primarily on conventional measures – albeit with a nuclear backstop. This would not necessitate any immediate changes in the deployment of US nuclear weapons, as these would be expected to support the task of responding to potential use of nuclear weapons by Russia, China or North Korea.

The current Russian nuclear doctrine lists ‘the totality of the military might’ of Russia alongside nuclear capabilities as contributing to deterrence of aggression. Following the 2025 ‘combat test’ use of the Oreshnik missile in the conventional mode, President Vladimir Putin described the missile as comparable to nuclear weapons in terms of damage. Considering its increased production rates for long-range missiles, Russia would again have the option to reduce the role of nuclear weapons in its posture and rely more on non-nuclear capabilities – although it is unlikely to move in that direction, and instead maintain or increase its reliance on nuclear weapons. India’s investments in conventional systems, including long-range strike and missile defence systems, could also point towards the possibility of its implementing elements of non-nuclear deterrence posture which would aim to influence the decision-making calculus of its adversaries (Pakistan and China) beyond the tactical and operational levels. Not only could China and India confirm their no-first-use pledges, but they could also aim to explain how their nuclear posture development and modernisation programmes relate to this political declaration, thus helping alleviate the concerns about the actual role of nuclear weapons in their policies. 

Chinese investments in conventional, counter-space and cyber capabilities could be seen as potential building blocks of a strategy of minimising the role of nuclear weapons, in line with its no-first-use posture. However, these capabilities can also support a coercive strategy of gaining advantage over adversaries in regional contingencies and limiting or increasing the costs of US engagement, by confronting the US with the choice between a conventional defeat and escalation to the nuclear level. This may influence the states around China to invest in non-nuclear capabilities to deter Chinese attempts at conventional forces-backed coercion, thereby potentially increasing the importance of nuclear weapons for China. 

Over time, the development of non-nuclear deterrence postures may lead to a reduction in sub-strategic nuclear weapons meant to address threats other than large-scale nuclear attack, or to decisions to refrain from development and deployment of new nuclear weapon systems. This could also allow re-allocation of resources from the nuclear to conventional part of the defence budgets. The move towards a minimal nuclear deterrence posture may also allow for diplomatic initiatives aimed at initiating new arms control agreements. 

Taken together, these developments towards strengthening conventional capabilities could influence regional security and decrease the salience of nuclear weapons – albeit at different paces in different regions. Adversaries would also need to engage in a parallel process of initiating dialogues on the consequences of nuclear–conventional rebalancing for strategic stability, and elements of the risk-reduction agenda. The process of reducing the reliance on nuclear weapons would at best be incremental, and each of the countries involved would probably wait to test the consequences of the reductions and the response from other nuclear-armed states before proceeding with the next steps. In case of the US, a consultation and coordination process involving its extended nuclear deterrence allies would need to be conducted to identify the measures which would strengthen non-nuclear deterrence posture. The first moves could be modest, involving changes in terms of doctrine and language used, rather than reductions in stockpiles or withdrawal of particular systems. Any potential follow-up would depend on the reception of the changes by a state’s adversaries and the subsequent assessment of the situation. 

Conclusions and Recommendations 

Outlining detailed designs for a global security system without reliance on nuclear weapons would be a futile exercise without addressing prospects for their implementation. Instead of suggesting a radical rejection of nuclear deterrence, a more realistic option may be to recommend a gradual narrowing down of the roles played by nuclear weapons. 

Consequently, this paper suggests shifts for decision-makers in four parallel areas: 

• political (reduction of tensions between nuclear-armed states);
• doctrinal (examining both reducing the range of scenarios for nuclear weapons use and options for doctrinal changes);
• military (substitution of nuclear weapons by conventional ones in some roles); and
• risk reduction and arms control. 

The room for manoeuvre in reducing the salience of nuclear deterrence in the current international situation appears limited. Nuclear-armed and nuclear-umbrella states regard nuclear weapons as a central part of their countries’ security. Nuclear deterrence is perceived by all possessor states as the ultimate guarantee or bedrock of national security, especially as protection against nuclear attacks. 

Progress in this regard would therefore probably need to be incremental. For nuclear weapon possessors, the most entrenched function at the core of their conceptualisation of nuclear weapons’ value is deterring nuclear use by an adversary, either against one’s own territory or (when applicable) that of an ally. More fundamentally, nuclear weapons provide an ultimate guarantee or backstop against existential threats to political regimes in extreme circumstances of self-defence. Nuclear-armed states currently see no comparable non-nuclear replacement for that role.

With respect to the second-tier roles of nuclear weapons, nuclear possessors could, as part of a first phase of the process of addressing the salience of nuclear weapons, initiate a national and alliance-level examination of the credibility of use, the potential effects, the legality and the utility of nuclear weapons in various scenarios, to identify which roles could be discontinued or where nuclear weapons could be replaced or supported by other means.

The process of reducing reliance on nuclear weapons can be conceptualised along the following paths, which could be pursued in parallel.

1. Set Policy 

Explicitly reject the role of nuclear weapons as a source of national and international status and prestige and recommit to nuclear disarmament, for example through a P5 policy statement. 

2. Assess the Utility of Nuclear Weapons

Examine the record of the usefulness and effectiveness of nuclear weapons as instruments of deterrence, influence or coercion during crises and conflicts, their utility in hybrid war scenarios, and their utility in dealing with threats emanating from non-state actors. Such assessment can be conducted at national or alliance levels.

Lessons learned so far from the war in Ukraine point to the questionable value and utility of Russian attempts to use its nuclear arsenal for intimidation purposes against both Ukraine and partners providing military assistance.

3. Consider Alternative Deterrence Options

Consider replacing the roles currently earmarked for nuclear weapons in specific scenarios and missions within doctrines and military planning. An across-the-board substitution of nuclear weapons by conventional military capabilities would probably not be feasible or advisable in the current political environment. However, where nuclear possessors envisage a non-strategic/battlefield mission for their nuclear forces, and envisage the use of nuclear weapons to deter non-nuclear attacks, these possessors could review the effectiveness of such threat or use in specific scenarios, examining the nuclear option against available non-nuclear instruments. This could lead to doctrinal adaptations, although participant states may have concerns about the negative implications in terms of weakening the credibility of deterrence and alliance cohesion. 

4. Pursue Nuclear Risk Reduction

As part of the process of reducing the role of nuclear weapons, unilateral, bilateral and multilateral nuclear risk reduction measures would be needed to increase the effectiveness of crisis communication and address the dangers of accidental or inadvertent escalation to nuclear level. In-depth dialogue between the nuclear possessors about their doctrines, re-introducing the discussion on diminishing the roles of nuclear weapons in the NPT and P5 contexts, and using other instruments of engagement such as track 1.5 channels (involving government officials, non-governmental experts and former officials to correctly assess other possessors’ doctrines) may be useful in the process of ‘right-sizing’ nuclear deterrence at the national and alliance level.