What role will nuclear weapons play in the 2020s?

Introduction

“The chief purpose of our military establishment has been to win wars. From now on, its chief purpose must be to avert them.” Bernard Brodie’s statement at the dawn of the nuclear age captures the foundational logic of nuclear deterrence: under the later logic of Mutual Assured Destruction, this type of weaponry should not be designed to be used, but to prevent another large-scale war. However, in the current decade, the role of nuclear weapons is being reassessed in a profoundly transformed strategic environment, characterized by multipolarity, the erosion of arms control treaties, and the emergence of Emergent and Disruptive Technologies (EDTs).

The paper examines whether these advancements have affected the essential function of nuclear weapons in the current decade. It argues that nuclear weapons continue to serve primarily as deterrents despite their increasing complexity and mounting risks. Even if their role in providing diplomatic assurance has expanded, their military utility remains limited.

To this end, the paper explores the concept of nuclear deterrence, then analyzes current geopolitical and technological developments, in order to subsequently assess the implications for the role of nuclear weapons on the global stage.

Nuclear deterrence

A classical definition of deterrence is “the manipulation of an adversary’s assessment of the cost-benefit analysis of taking a given action. By reducing prospective benefits or increasing prospective costs (or both), one can convince the adversary to refrain from taking that action.”[1] James J. Wirtz argues that conventional and nuclear deterrence differ strategically, but that, in both cases, “Regardless of the weapons employed or the strategy adopted, capability and credibility are the key ingredients of successful deterrence.”[2]

The difference between the two types of deterrence lies in contestability. Conventional deterrence is contestable on the battlefield, whereas nuclear deterrence, with its catastrophic consequences, is largely uncontestable. This affects credibility: nuclear weapons are well-suited to retaliatory deterrence, while conventional forces are better suited to punishment and denial strategies.[3]

In light of the new strategic environment, Keith B. Payne emphasizes the critical importance of prudence, which requires flexible and resilient nuclear and non-nuclear deterrence capabilities to deter threats arising from diverse and evolving contexts.[4]

This is important because uncovering an adversary’s intentions must be understood as a psychological process. According to Michael J. Mazarr, this depends on how the adversary’s activity affects our perception of risks and feelings of uncertainty.[5]

We recall the well-known statement by Colin Gray, who said that “to deter, an ounce of will is worth more than a kilo of muscle.”[6] However, will is more unstable than capabilities, which explains why nuclear states maintain their deployment of force and declarative postures in line with their nuclear doctrine.

Significant New Developments in the 2020s

Unlike during the Cold War, the current geopolitical landscape is multipolar, with diverse nuclear actors and EDTs complicating the nuclear order. Deterrence remains relevant, even though its credibility is challenged by new strategic calculations and regional dynamics.[7]

The war in Ukraine has become a game-changer, as it has exposed both the strengths and limitations of nuclear deterrence. On the one hand, Russia has demonstrated how nuclear capabilities can be used to influence the dynamics of conventional warfare in order to deter direct intervention by third parties.[8] On the other hand, it has failed to deter Ukraine’s resistance, even with the threat to use tactical nuclear weapons (TNWs).[9] This has spurred an arms race and raised questions about extended deterrence in other regions, particularly the Asia-Pacific and the Middle East.[10] Since, “one consequence of the war might be that advocates of nuclear weapons scale back their claims and ambitions.”[11]

Although Ukraine serves as a central case study, a broader geographical perspective reveals that deterrence dynamics vary significantly across regions. In South Asia, the India–Pakistan rivalry represents a relatively stable yet inherently dangerous deterrence relationship, characterized by short warning times, risks of conventional escalation, and the persistent possibility of nuclear use. In the Middle East, the conflict between Israel and Iran reflects a particularly complex deterrence environment, where nuclear asymmetry and ambiguity interact with increasingly autonomous regional security arrangements. The emergence of the Makkah Joint Defense Agreement between Saudi Arabia, Türkiye, and Pakistan adds a new layer to this dynamic by linking a major regional power to a collective defense framework that includes a nuclear-armed state.

Across these cases, a common pattern emerges: increasing uncertainty and heightened risks of escalation driven by regional tensions and evolving strategic calculations. This uncertainty is further reinforced by concerns about the reliability of extended deterrence, particularly in light of fluctuating U.S. foreign policy commitments. As a result, debates about alternatives to the U.S. nuclear umbrella have intensified, especially in Europe. In this context, France has garnered renewed attention due to its independent nuclear arsenal and its potential role in strengthening European deterrence. While French nuclear doctrine remains strongly tied to national sovereignty, these discussions highlight its growing relevance within the European security architecture.

Overall, these developments show that nuclear deterrence in the 2020s is not uniform, but is increasingly shaped by regional dynamics, strategic cultures, and threat perceptions.

Some authors believe that this new arms race and the goal of deterrence are changing the nuclear order—which encompasses the set of practices and norms that govern the use of such capabilities according to certain logics.[12]Despite this, it does not mean “slouching toward a nuclear Gomorrah,” since, according to Stephen Herzog, “the foundation of international nuclear governance is more robust than is often assumed.” Even so, mistrust among nuclear powers is putting several traditional multilateral arms control agreements under strain. The ABM Treaty of 1972 and the INF Treaty of 1987 were already dysfunctional before the war. At the same time, New START—intended to bring transparency and limits to strategic launchers and deployed warheads—is set to expire after 2025.[13] Other treaties, such as the Comprehensive Test-Ban Treaty (CTBT) and the Outer Space Treaty, are being called into question as the nuclear taboo erodes.[14]

The challenge posed by nonproliferation is based on assurance. These terms are often mistakenly used interchangeably with “extended deterrence.” Extended deterrence refers to “influencing adversaries to prevent attacks on allies,” whereas assurance is “directed at convincing allies.” As stated by Jennifer Bradley, “Just as deterrence is a cognitive function in the mind of the adversary, assurance is a cognitive function in the mind of the ally.”[15] This assurance is increasingly being questioned, particularly with regard to the U.S. security umbrella. A notable example is the Republic of Korea, which signed the Washington Declaration and agreed to the establishment of the Nuclear Consultative Group (NCG) in April 2023. This followed Sun Yeok’s openness to the idea of the ROK developing its own nuclear capabilities. Through the NCG, assurance was intended to be provided through conventional-nuclear integration (CNI).[16] Japan and Australia, traditionally opposed to the buildup of nuclear capabilities, are also discussing the possibility of nuclear-sharing agreements.[17] Russia has also shifted its position on nuclear sharing by providing protection to Belarus through the deployment of tactical nuclear weapons on its territory.[18]

The newly established Makkah Joint Defense Agreement between Saudi Arabia, Türkiye, and Pakistan provides a further illustration of this trend. Signed in August 2026, the agreement establishes a collective defense framework under which an armed attack against one signatory is treated as an attack against all three. Although the agreement is formally defensive and does not explicitly identify an adversary, its significance lies in the combination of Saudi economic power, Turkish military capabilities, and Pakistan’s nuclear deterrent. Rather than relying exclusively on the U.S. security umbrella, Saudi Arabia is therefore participating in the construction of an alternative regional security architecture. This reinforces the importance of assurance as a component of deterrence: when the credibility of external guarantees is questioned, states may seek to diversify their security arrangements rather than immediately pursue independent nuclear capabilities. The agreement consequently illustrates how the role of nuclear weapons in the 2020s is becoming increasingly embedded in complex regional deterrence relationships.

The trend toward emerging dual-use technologies (EDTs), such as hypersonic weapons, cyber capabilities, and AI, may have a much greater impact on the future of nuclear deterrence now than in previous debates.[19] Several authors have noted that EDTs create vulnerabilities in nuclear capabilities, as they can make an attack on an enemy’s nuclear forces and infrastructure—such as early-warning and command-and-control systems—more credible. This entails “a negative effect on crisis stability, by neutralizing or at least minimizing the so-called stabilizing effect of nuclear weapons.”[20]

Keir A. Lieber and Daryl G. Press further explore this issue by analyzing the survivability of nuclear arsenals—traditionally based on hardening and concealment—which are increasingly being eroded by significant advances in weapon accuracy and a revolution in remote sensing technologies. This development has profound implications: the combination of enhanced precision and improved surveillance makes nuclear attrition strategies more viable, enabling a counterforce scenario in which a first, disarming strike (attrition, eliminating most of an adversary’s capabilities) becomes markedly more plausible, thereby weakening the retaliatory logic of nuclear deterrence. Nevertheless, vulnerabilities can also be reduced through EDTs: “The new era of counterforce will not be static; it will be characterized by vigorous efforts to develop countermeasures, as well as equally vigorous efforts to overcome them.”[21]

How has the role of nuclear weapons changed?

In 1983, Robert S. McNamara wrote an article titled “The Military Role of Nuclear Weapons: Perceptions and Misperceptions.” In it, he noted that there are three incompatible views on the role of nuclear weapons: (1) TNWs can be used in a limited way for combat; (2) They have no military utility and their function is deterrence to prevent the enemy from using them first; (3) What maintains the deterrence against a conventional attack is the threat of using them first. According to McNamara, a strategic first strike is not possible because it implies MAD. He also considers the use of TNWs to be militarily useless and politically suicidal, as they would facilitate a bloody escalation. McNamara’s statement on the role of nuclear weapons is clear: “Nuclear weapons serve no military purpose whatsoever. They are totally useless, except only to deter one’s opponent from using them.”[22] It is now necessary to consider whether new geopolitical dynamics and the development of EDTs have altered that exclusive role of deterrence.

Despite this, the discussion over the utility of TNWs remains highly contested. Classical strategic thinkers, such as André Beaufre[23] and Michael Qinlan,[24] argue that TNWs contribute to the credibility of deterrence by filling the “gap” between conventional forces and strategic nuclear retaliation. From this perspective, limited nuclear options are necessary to make deterrence more flexible and therefore more credible in scenarios where full-scale retaliation would be disproportionate. In fact, this logic is reflected in NATO’s longstanding reliance on dual-capable aircraft and forward-deployed nuclear capabilities,[25] as well as in the ongoing modernization of systems such as the U.S. Navy’s Trident force, which includes modifications to the W76 warhead.[26] These developments suggest that TNWs, rather than disappearing, remain integrated into operational planning as tools for escalation control and signaling. As part of their deterrence strategy, even nations like France emphasize the importance of air-launched nuclear weapons as a “last warning” capability. This implies that TNWs are still part of the broader discussion regarding whether limited nuclear use enhances or jeopardizes strategic stability.

According to Duchy and Bradley, TNWs play a primarily cohesive role within NATO, with a secondary military impact, since their direct military function has diminished due to U.S. conventional superiority. However, they serve as a visible signal of the U.S. defense commitment to Europe. Just as TNWs decreased between 1980 and 2000 following the INF Treaty, the current trend is reversing due to weakening treaties and states’ need for assurance. Nevertheless, the role of TNWs varies depending on nuclear doctrine. For Russia, the use of TNWs is intended to force a de-escalation strike—that is, to en network s through compliance. This stance stems from Russia’s conventional inferiority compared to NATO and China’s numerical superiority.[27] One of the first instances of coercion through TNWs has been observed in Ukraine. During the Ukrainian offensive on Kherson, Russia reportedly signaled the possible use of TNWs to Western capitals, illustrating their limited but non-negligible coercive role. This supports Per Duchy and Bradley A.’s argument that the military role of TNWs is secondary, though not entirely absent, contrary to McNamara’s view.[28]

Regarding the possibility of a first strike, Tom Sauer describes how an operation would be carried out to disable the enemy’s retaliatory deterrence through the use of EDTs. The first step would involve neutralizing early warning systems. This can be achieved by generating noise to interfere with satellites, spoofing, electromagnetic interference, cyberattacks, or a precision strike against radar systems. Second, cyber and kinetic weapons would be used to neutralize the enemy’s nuclear forces. ICBMs are vulnerable to cyberattacks, and there is debate over whether submarines—currently considered nearly invulnerable—might be susceptible to hacking. In fact, submarines may already be vulnerable to detection by sensors on autonomous underwater drones or swarm robotics. Finally, C2 will be the element most isolated from the internet, but cyberattacks remain plausible—both disabling and enabling. Therefore, states “will be under immense pressure to safeguard their own nuclear forces and systems in a crisis, and as a result, use them, possibly even preemptively.”[29]

However, several authors disagree with this view. Lieber and Press note that increased precision reduces hardening protection but does not prove that all systems can be neutralized. His own analysis relies on broad assumptions about future technological capabilities and does not prove that a fully effective first strike is achievable. Similarly, Andrew Futter does not deny that disruptive technologies pose challenges, but he criticizes the tendency to believe that these technologies alone will render nuclear deterrence obsolete. Human decisions are more important than technology alone for nuclear stability, and oversimplifying technology can lead to a failure to understand the difference between theory and practice.[30]

So, despite new geopolitical dynamics and EDTs, McNamara was essentially right: nuclear weapons remain primarily an instrument of deterrence. The potential military use of TNWs is still very limited and occurs only in situations of vital interest, and EDTs are not yet capable of undermining strategic stability. This does not mean, as James M. Acton points out, that the risks have not increased, especially in relation to the entanglement arising from dual-use command, control, and communication systems.[31] Likewise, it is important to examine whether the role of deterrence has changed, taking into account the traditional dual purpose of strategic deterrence: preventing aggression while promoting global nuclear stability.[32]

With regard to the preventive use of nuclear weapons, this is most clearly evident in recent conflicts, where such weapons have shaped the scope and limits of aggression without actually being used. In the case of Ukraine, Russian military doctrine emphasizes that nuclear deterrence applies when Russia’s territory or vital interests are in danger. This has allowed for direct non-intervention by third parties, which illustrates how nuclear weapons can enable conventional aggression while simultaneously limiting its horizontal expansion. As in the Cold War, this avoids interstate escalation while the war takes place in a third state. Likewise, although the war has only occurred in Europe, tensions have arisen in the Asia-Pacific region.

Avner Cohen argues that Israel’s nuclear posture is designed not to deter low-level or asymmetric attacks, but to prevent large-scale aggression by regional adversaries or coalitions that might threaten its survival. [33] The escalation resulting from the Hamas attack on October 7, 2023, reinforces this distinction. As Tsili Lahav, head of Israel’s economic mission in Spain, noted, Israel is “a two-bomb state.” Hypersonic missiles are capable of bypassing the Iron Dome. Therefore, equipping just a few of these missiles with nuclear warheads could lead to the destruction of an extremely small state. Hence, Operation Night Hammer sought to disable the Iranian nuclear program before it became operational, at all costs. Consequently, while nuclear deterrence plays a vital role in ensuring survival, it proves insufficient to deter limited, asymmetric, or subconventional forms of aggression.[34]

Conclusion

This analysis shows that, despite significant geopolitical and technological changes, the fundamental role of nuclear weapons in the current decade remains that of nuclear deterrence.

The war in Ukraine and tensions in the Asia-Pacific region demonstrate how nuclear deterrence serves to prevent regional conflicts from escalating into broader confrontations that could affect the vital interests of nuclear powers. Nuclear weapons therefore serve primarily as instruments of strategic deterrence and as a means of limiting the intervention of third states, rather than as instruments of direct combat. As for TNWs, although they currently have a very limited military effect as instruments of compellence, they play a diplomatic role in providing assurance. However, other measures, such as NCGs, have also had to be established.

EDTs pose unprecedented challenges to strategic stability by increasing the vulnerability of early warning systems (EWSs) and nuclear arsenals, while potentially hindering command and control (C2). Despite this, EDTs have not replaced the logic of deterrence, since the risks posed by these technologies ultimately remain shaped by human perception.

In conclusion, in order to ensure strategic stability in this decade, we must recognize that nuclear weapons have not lost their relevance; rather, their role has become more complex. Above all, this requires prudence and constant strategic adaptation.