Deterrence is a fundamental pillar of international relations, a strategy designed to shape the behaviour of adversaries through the credible threat of imposing unacceptable costs or denying strategic benefits. Rooted in the theoretical framework of realism, which conceives of the international system as anarchic and states as rational actors that prioritise survival and the maximisation of relative power (Waltz, 1979; Mearsheimer, 2001), deterrence has evolved from its nuclear focus during the Cold War to encompass domains as diverse as the economic, cultural, biotechnological, climatic, energy, cyber and space.

This analysis proposes, among other things, to explore deterrence in its many facets, with a particular emphasis on hard power, grey zone warfare (especially in China and Russia), energy deterrence, cyber deterrence, climate deterrence, soft power and smart power. The doctrinal evolution of deterrence in the United States, the Soviet Union/Russian Federation, China, the United Kingdom, France, India and Pakistan, integrating historical examples and contemporary trends up to October 2025.

Introduction

Realism, as the dominant paradigm in international relations, provides a robust analytical framework for understanding deterrence not only as a military tactic, but as a structural mechanism inherent in the anarchic system. In this context, deterrence is not merely reactive, but proactive, designed to alter the rational calculations of adversaries in an environment where the absence of a central authority encourages perpetual competition for power (Morgenthau, 1948).

The evolution of deterrence reflects changes in the distribution of global power, from the bipolarity of the Cold War to contemporary multipolarity, where actors such as China and Russia challenge the US-led order through hybrid and asymmetric strategies (Costlow, 2025).

This multidimensional expansion of deterrence incorporates not only nuclear weapons, but also cyber, economic and climate tools, which exacerbate asymmetries in relative power and complicate strategic stability (Lieber & Press, 2023).

Furthermore, Russian and Chinese perspectives, influenced by their own realist traditions, emphasise deterrence as an instrument for preserving sovereignty in a world dominated by Western hegemony, integrating elements of unconventional warfare and resource control (Kortunov, 2023; Wu, 2023).. This comprehensive narrative seeks not only to describe deterrence, but also to assess its ethical and strategic implications in an increasingly volatile global landscape.

1. The realist framework and the foundations of deterrence

Realism in international relations provides the theoretical lens through which deterrence is analysed. According to Kenneth Waltz (1979), the international system lacks a supranational authority, forcing states to ensure their own security through the accumulation of power. In this logic, deterrence is a coercive tool that seeks to prevent adverse actions by projecting the ability to impose costs or deny benefits, thus preserving national interests in a competitive environment. John Mearsheimer (2001), from an offensive realism perspective, argues that states not only seek to survive, but also to maximise their power to achieve hegemony, which intensifies the need for credible deterrence strategies. Thomas Schelling (1966), in his seminal work Arms and Influence, defines deterrence as ‘the art of persuading an adversary that the consequences of acting will be more costly than the benefits’ (p. 2). This principle underscores the importance of credibility, which depends on three interconnected elements: capability, willingness, and communication.

Classical realism, represented by figures such as Hans Morgenthau, emphasises that deterrence arises from the inherent human condition of conflict, where power is the primary means of state survival (Morgenthau, 1948).

In the neorealist context, Waltz (1979) argues that the bipolar structure of the Cold War fostered stable deterrence, as nuclear parity between superpowers minimised incentives for pre-emptive strikes.

However, the transition to a multipolar system has complicated this dynamic, with revisionist actors such as China and Russia exploiting asymmetries to challenge the status quo (Mearsheimer, 2014). Russian perspectives, influenced by defensive realism, see deterrence as a means to counter NATO expansion, integrating hybrid elements that combine military power with economic influence (Kortunov, 2023). In China, the doctrine of ‘minimal deterrence’ (威慑最小化) aligns with an adapted offensive realism, prioritising denial of access in disputed regions such as the South China Sea (Wu, 2023).

These variations illustrate how realism is not monolithic, but adaptable to cultural and strategic contexts, where deterrence acts as a balancer in an anarchic system. Recent studies highlight that in a post-bipolar world, deterrence must incorporate non-state and cyber threats, broadening the concept beyond the military (Nye, 2017). This theoretical deepening reveals that deterrence is not static, but evolves with power distributions, requiring constant credibility to avoid miscalculations that could escalate into major conflicts (Jervis, 1985).

1.1. Essential elements of deterrence

Effective deterrence in the realist framework rests on three fundamental pillars:

  • Capacity: A state or entity comparable to a state power within a federation must possess the necessary resources to back up its threat, whether through military (hard power), economic, cultural (soft power), or technological (biotechnological, climatic, energy, cyber, space) power.. Capacity reflects the relative power of a state in the international system, a central concept in realism (Waltz, 1990). In the nuclear context, capacity manifests itself in the strategic triad, which ensures survivability and retaliatory strike capability (Freedman, 2004). However, in emerging domains such as cyber, capacity depends on resilient infrastructure and cutting-edge technologies, where asymmetries can favour non-traditional actors (Nye, 2017). German studies on Abschreckung (deterrence) emphasise that capacity must be demonstrable in order to maintain the balance of power, avoiding gaps that invite aggression (Terhalle, 2023). Italian perspectives, influenced by classical realism, highlight the integration of economic capacity into deterrence, as in European sanctions against Russia (Pantani, 2024).
  • Will: The willingness to use these resources must be perceived as genuine by the adversary. Will is built through historical actions, strategic rhetoric, and consistent signals. For example, US intervention in the Gulf War (1991) reinforced its reputation as an actor willing to use force (Jentleson et al., 1992). In Russian terms, will is demonstrated through ‘active deterrence’ (сдерживание активное), which includes military exercises and hybrid operations to project resolve in pursuing objectives following Clausewitz's maxim that war is the continuation of politics by other means (Kortunov, 2023). China has been arguing at the theoretical-doctrinal level that will is culturally contingent, with Beijing prioritising strategic patience over direct confrontation (Wu, 2023). The erosion of will, as in the withdrawal from Afghanistan (2021), can undermine global credibility, encouraging challenges from rivals (Biddle, 2021).
  • Communication: The threat must be clear, understandable and adapted to the cultural and strategic context of the adversary. Ambiguity or misinterpretation of signals can undermine credibility, as occurred at certain points towards the end of the Second World War and in the events leading up to the Cold War (Martín Menjón, 2022), and in the Korean War (1950-1953), when China underestimated the US willingness to intervene (Jervis, 1985). In French realism, communication is seen as a diplomatic art, integrating narratives to reinforce the so-called ‘dissuasion nucléaire’ (Tertrais, 2024). China has been emphasising that Chinese communication in the South China Sea uses historical symbolism to deter without escalation (Li, 2024). Applied game theory reveals that asymmetric communication can lead to deterrence failures, as in cyber crises (Brams, 2011).

Credibility, as the intersection of these elements, is at the core of deterrence. In an anarchic system, where trust is limited and intentions are opaque, the adversary's perception of the deterrent's capability and willingness determines the success of the strategy. Recent research suggests that in multipolar environments, credibility requires the integration of hard and soft power to counter tactics in the so-called “grey zones” (Hoffman, 2018; Martín Menjón, 2022a). Russian perspectives emphasise credibility through “escalation for de-escalation”, in which tactical nuclear threats reinforce will (Giles, 2025). This interconnection underscores that deterrence is a dynamic process, susceptible to misperceptions at both cognitive and cultural levels, requiring constant adaptation to maintain stability (Jervis, 1985).

1.2. Types of deterrence

Deterrence manifests itself in multiple forms, each tailored to specific contexts and aligned with the realist logic of power maximisation:

  • Direct deterrence: Protects territory or interests against a direct threat, such as the US nuclear doctrine against the Soviet Union during the Cold War (Freedman, 2004). In the current context, this includes defences against hypersonic missiles, where Russia and China have advanced technologies that challenge US superiority (Lieber & Press, 2023).
  • Extended deterrence: This involves the defence of allies, such as the United States' commitment to NATO, which reinforces its global hegemony (Huth, 1988). France emphasises extended deterrence in Europe, where the French ‘force de frappe’ contributes to collective security (Tertrais, 2024). The ‘Force de frappe’, also known as the French nuclear deterrent force (‘Force de dissuasion’), is the central pillar of French nuclear doctrine, developed mainly under Charles de Gaulle in the 1960s. This doctrine is based on the principle of independent nuclear deterrence, with the aim of guaranteeing France's national sovereignty and strategic autonomy, especially in the context of the Cold War and the Atlantic Alliance (NATO). The ‘Force de frappe’ represents France's ability to inflict “unacceptable” or ‘lethal’ damage on any potential aggressor, thus deterring any attack by making the cost disproportionate to the benefits. Originally conceived as a ‘strike force’, it evolved into a nuclear triad (air, land and submarine) with an omni-directional, strictly defensive and ‘strictly sufficient’ posture, i.e., without seeking parity with superpowers such as the United States or the USSR, but focusing on damaging the enemy's vital centres (economic, political and military) to protect vital French interests and, by extension, those of Europe. This doctrine was promoted to avoid total dependence on US nuclear protection, arguing that ‘the defence of France must be French’ and that alliances, and this is a key lesson if we are not in a federal structure, do not guarantee absolute commitments in a nuclear context or in any form of conflict, where an ally might hesitate to risk its own destruction out of self-interest, fear or convenience. The Force de frappe was formalised after the first French nuclear test in 1960 and became part of the policy of national ‘grandeur’, contributing to France's withdrawal from NATO's integrated command in 1966, with the ambition of creating a French Western Europe in the context of French détente towards the USSR in 1966, which was later overtaken by events and by US détente towards the USSR in the 1970s (Université de Franche-Comté & Institut Charles de Gaulle, 1985; de Gaulle, 1970; de Gaulle, 2000; Ministère de la Défense; 1972; Gallois, 1960).
  • General deterrence: Prevents long-term conflicts through the constant projection of power, such as that pursued by the United States with its military presence in the Indo-Pacific to counter China (Morgan, 2003). Chinese perspectives see this as containment, responding with area denial strategies (Wu, 2023).
  • Immediate deterrence: Responds to specific short-term threats, such as the Cuban Missile Crisis (1962) (Jervis, 1985). In 2025, this includes responses to Russian ASAT tests, which threaten space assets (Grego, 2017).
  • Nuclear deterrence: Based on the threat of catastrophic retaliation, underpinned by the nuclear triad in powers such as the United States, Russia and China (Freedman, 2004). Evolving developments include hypersonic weapons, reducing response times and challenging stability (Acton, 2020).
  • Conventional deterrence: Uses non-nuclear forces to deny the adversary's objectives, such as Israel's operations against Hezbollah in Lebanon (Covarrubias, 2009). In Asia, India has used this against Pakistan in border disputes (Basrur, 2023).
  • Cyber deterrence: Seeks to prevent attacks in cyberspace through digital retaliation or economic sanctions (Nye, 2017). Challenges include attribution, with Russia and China leading hybrid operations (Giles, 2025).
  • Space deterrence: Protects space assets, such as different types of satellites, from threats such as anti-satellite weapons (ASAT) (Yagües Palazón, 2018). In 2025, Chinese and Russian ASAT tests have intensified space militarisation (Li, 2024; Harrison, 2024). Multidimensional elements with implications for the evolution of air, land and sea combat, etc. (Martín Menjón, 2025a).
  • Economic deterrence: Uses sanctions, tariffs or economic incentives, such as the sanctions against Russia following the invasion of Ukraine (2022) (Gómez, 2023). Also noteworthy is China's use of rare earths for coercion (Hurst, 2023).
  • Cultural deterrence: Uses cultural narratives and soft power to shape perceptions, such as China's narratives of historical sovereignty in the South China Sea (Johnston, 2014). Extensions by Nye include integration with smart power (Wilson, 2008).
  • Biotechnological deterrence: Threatens the use of biological weapons or genetic technologies, although it raises ethical dilemmas (Koblentz, 2017). Advances in CRISPR (genetic editing technology that allows scientists to modify an organism's DNA) have raised proliferation risks (Bügl et al., 2023).
  • Climate deterrence: An emerging form that uses environmental policies or climate technologies to protect resources or delegitimise the adversary (Dalby, 2022). The EU's CBAM (or Carbon Border Adjustment Mechanism, a measure designed to equalise the price of carbon between imports and domestic production in the European Union) exemplifies this (Böhringer et al., 2022).
  • Energy deterrence: Controls access to key energy resources, such as gas or oil, to influence an adversary's behaviour (McGowan, 2023). Russia has used this against Europe (McGowan, 2023), and the United States is potentially preparing to occupy a position of definitive influence over Europe, similar to that of Russia.

Each type of deterrence reflects the realistic logic of competition for power, adapting to the available resources and strategic priorities of each state. In a multipolar world, these types overlap, creating complexities that require hybrid strategies to maintain balance (Hoffman, 2018). Russian and Chinese perspectives emphasise asymmetric deterrence to counter Western superiority (Kortunov, 2023; Wu, 2023).

1.3. Credibility and game theory

Credibility is the psychological and strategic core of deterrence. As Patrick Morgan (2003, 45) points out, ‘deterrence is a psychological game: its success depends on what your adversary believes you will do, not necessarily on what you will actually do.’

Game theory provides an analytical framework for understanding these dynamics, assuming that actors act rationally to maximise their benefits in a competitive system. In a basic model, deterrence is effective if the adversary perceives that the expected costs of acting outweigh the benefits:

Costs x P(Costs)>Benefits x p(Benefits)

Where P(Costs) is the perceived probability that the deterrent will carry out the threat, and P(Benefits) is the probability of success of the adversary (Brams, 2011).

Game theory models applied to deterrence include:

  • Chicken game: Two actors face the risk of a devastating conflict if both persist. Effective deterrence requires the actor with greater relative power to convince the other of their unwillingness to yield. A classic example would be the Cuban Missile Crisis (1962), where US military mobilisation and the clarity of its signals deterred the Soviet Union from escalating the conflict (Jervis, 1985). In 2025, this applies to tensions in the Indo-Pacific, where China uses tactics within grey zones to test US resolve (Hayton, 2022).
  • Signalling game: The deterrent sends signals to demonstrate capability and willingness. Information asymmetry can distort these signals, as in the Gulf War (1990–1991), where the US-led coalition projected a credible threat by mobilising 500,000 troops, deterring Iraq from expanding its aggression beyond Kuwait (Jentleson et al., 1992). Russian perspectives integrate signalling into ‘active deterrence,’ with exercises such as Zapad (Russian Ministry of Defence, 2024).
  • Repeated interaction game: Credibility is built through a history of consistent actions. Israel's response to Syrian threats during the Six-Day War (1967) reinforced its reputation as a conventional deterrent, influencing the perceptions of its adversaries in subsequent conflicts (Huth, 1997). In Asia, the India-Pakistan rivalry illustrates repeated interactions, with nuclear tests reinforcing mutual credibility (Sagan, 2009).

However, realism recognises that cognitive biases and cultural differences can distort perceptions of credibility. Robert Jervis (1985) highlights that leaders can misinterpret signals due to historical or cultural prejudices, as in the Korean War, when China underestimated the US willingness to intervene after UN troops entered, resulting in an unexpected escalation. These failures underscore the difficulty of maintaining credibility in an international system where intentions are opaque and trust is limited.

Recent research in game theory applied to cyberspace reveals that complicated attribution reduces credibility, allowing for grey zone tactics (Baliga & Sjöström, 2020).

For their part, Chinese perspectives are emphasising cultural signalling games, using historical narratives to deter (Johnston, 2014).

In short, game theory enriches realism by providing quantitative tools for analysing credibility, although it must be complemented by psychological and cultural factors to capture the complexity of contemporary deterrence (Lebow, 1981).

2. Hard power: the core of traditional deterrence

Hard power, defined as the ability of a state to impose its will through military force or economic coercion, is the traditional pillar of deterrence in the realist framework (Nye, 2004). In an anarchic system, hard power provides the material basis for projecting credible threats, whether through nuclear, conventional, economic or energy capabilities, among others. Realist logic emphasises that hard power is essential to deter direct aggression and ensure survival, as states assess the relative power of their adversaries in terms of tangible capabilities (Waltz, 1990).

In offensive realism, hard power is not only defensive, but a means of expanding influence, as in the case of Chinese military modernisation (Mearsheimer, 2001), which is shifting towards warning the United States that it will strangle China in key bottlenecks in the Indo-Pacific. Russian perspectives see hard power as a counterweight to Western hegemony, integrating nuclear and conventional forces for ‘active deterrence’ (Kortunov, 2023). In 2025, hard power faces proliferation challenges, with India and Pakistan developing nuclear triads for regional balance (Basrur, 2023; Khan, 2023), which could prompt other actors or alliances of actors to follow suit. This section delves into how hard power evolves in response to disruptive technologies, maintaining its centrality in realistic deterrence.

2.1. Nuclear deterrence and the nuclear triad

Nuclear deterrence, underpinned by the nuclear triad:

1) Intercontinental ballistic missiles [ICBMs];

2) Submarine-launched ballistic missiles [SLBM]; and

3) Strategic bombers.

This is the most extreme expression of hard power.

The triad ensures a state's ability to inflict catastrophic damage, even after a pre-emptive strike, which reinforces credibility in contexts of mutually assured destruction (MAD). Its components are:

  • Intercontinental ballistic missiles (ICBMs): Deployed in land-based silos, such as the US Minuteman III, the Russian Topol-M or the Indian Agni-V, ICBMs offer rapid launch and global reach. However, their vulnerability to pre-emptive strikes and hypersonic weapons poses challenges (Lieber & Press, 2023). In Russia, the modernisation of ICBMs such as the Sarmat improves penetrability against defences (Russian Ministry of Defence, 2024).
  • Submarine-launched ballistic missiles (SLBMs): Nuclear submarines, such as the Ohio class (United States), Vanguard (United Kingdom) and Arihant (India), are virtually undetectable, ensuring a robust second-strike capability. SLBMs, such as the Trident II, are at the core of nuclear credibility (Freedman, 2004). China has advanced with the Jin class, expanding its reach in the Pacific (Li, 2024).
  • Strategic bombers: Platforms such as the US B-2 Spirit or, to a certain extent, the French Rafale, which could be defined as a kind of Swiss Army knife, being a highly versatile “omnirol” capable of performing a wide range of missions (air superiority or air-to-air combat missions; interdiction; ground support; deep strikes; aerial reconnaissance; anti-ship attacks and, if necessary, operate as a nuclear deterrent) without the need for specialised reconfigurations, offer operational flexibility as they can be withdrawn or redirected. However, their vulnerability to modern air defences limits their credibility in high-intensity scenarios (Sagan, 2009). Russia maintains the Tu-160 for global projection (Giles, 2025).

The nuclear triad reinforces deterrence by diversifying launch platforms, reducing the risk of total neutralisation. Historical examples illustrate its effectiveness:

  • Cuban Missile Crisis (1962): The US nuclear triad, with Minuteman ICBMs, Polaris SLBMs and B-52 bombers, projected a credible threat that deterred the Soviet Union from escalating the conflict (Jervis, 1985).
  • Euromissile crisis during NATO's Able Archer exercise (1983): NATO exercises simulating a nuclear attack highlighted the credibility of the Western triad, although they raised fears of escalation in Moscow (Freedman, 2004).

Contemporary challenges include the modernisation of obsolete systems, such as the US GBSD programme (Ground Based Strategic Deterrent, an USAF initiative to replace its Minuteman III intercontinental ballistic missile (ICBM) system. The programme, also known as LGM-35 Sentinel), vulnerability to cyberattacks on command and control systems, and the proliferation of hypersonic weapons, which reduce response times (Acton, 2020; Lieber & Press, 2023).. In India and Pakistan, the emerging triad creates a regional MAD, but with risks of accidental escalation (Sagan, 2009). France emphasises ‘nuclear sufficiency’ to guarantee autonomy (Tertrais, 2024). Until 2025, the triad remains central, but requires integration with non-nuclear domains to counter hybrid threats (Costlow, 2025).

2.2. Conventional deterrence

Conventional deterrence uses non-nuclear forces to deny the adversary's objectives or impose significant costs. From a realist perspective, it reflects the need to project military power in regional or asymmetric conflicts, where the nuclear threat is less credible (Covarrubias, 2009).

I will cite two paradigmatic examples:

  • Israeli operations in Syria (2010s-2020s): Air strikes against Hezbollah and Iranian militia facilities deterred the expansion of Iranian influence in the region, demonstrating the effectiveness of air superiority against this type of adversary (Covarrubias, 2009).
  • US military presence in the Indo-Pacific: The rotation of aircraft carriers and bases in Japan and South Korea deters China from aggressive actions in the South China Sea (Morgan, 2003). China responds with A2/AD to deny access (Wu, 2023).

Conventional deterrence depends on technological superiority, speed of deployment and perceived willingness. However, protracted conflicts, such as the wars in Iraq and Afghanistan, can erode credibility by exposing the limits of political will (Biddle, 2021).

In Europe, NATO integrates conventional and nuclear forces to deter Russia (Giles, 2025). Theses on South Korea highlight conventional deterrence against North Korea, combined with allies (Bowers & Hiim, 2021).

2.3. Challenges to hard power

Hard power faces several challenges in the 21st century:

  • Economic costs: Maintaining nuclear arsenals and advanced conventional forces requires massive investments, such as the $634 billion US defence budget in 2023 (Lieber & Press, 2023).
  • Technological asymmetries: Hypersonic weapons and drones are reducing the technological advantage of the major powers (Lieber & Press, 2023). China and Russia are leading the way in hypersonics, challenging the US triad (Li, 2024).
  • Perception of will: The US withdrawals from Afghanistan (2021) and Vietnam (1975) have raised doubts about its long-term commitment, affecting its credibility (Biddle, 2021). This is evident in Ukraine, which could be understood as a transactional conflict of interests between the US and Russia. This invites tests by rivals such as Ukraine (Giles, 2025).
  • International norms: Excessive use of force can trigger global criticism, weakening the legitimacy of the deterrent (Nye, 2002). The NPT and treaties limit proliferation, but revisionists challenge them (Sagan, 2009).

Despite these challenges, hard power remains at the core of deterrence in the realist framework, as it provides the material basis for projecting credible threats in a system where military power determines survival. Integration with soft power into smart power mitigates some challenges, but realism warns that without hard power, deterrence fails (Wilson, 2008).

3. Soft Power: Deterrence through Cultural Attraction

Soft power, defined by Joseph Nye (2004, 5) as ‘the ability to get what you want through attraction rather than coercion,’ is a key component of cultural deterrence. From a realist perspective, soft power does not replace hard power, but rather complements it by legitimising the actions of a state and delegitimising those of its adversaries, thereby reinforcing credibility in a competitive system (Mearsheimer, 2001). Soft power operates through culture, political values, public diplomacy and global narratives, shaping perceptions to deter without resorting to force.

In Nye's extension, soft power is seen as a multiplier of power in multipolarity, where China uses Confucius Institutes to counter Western narratives (Nye, 1990; Zhang, 2025). Other tools are beginning to be added along Japanese lines in anime, graphic novels, graphic adventures, or what could be the new Hello Kitty characters focused on China, such as Labubu and Mokoko, something we will be working on soon at the Symposium Institute. For their part, from the Russian perspective, soft power is integrated with disinformation to weaken Western cohesion through liberal means (Singer & Brooking, 2021), which allows for the refinement of concepts of power, dominance and hegemony, something to which Europe must either generate its own responses or end up entering with full force. This section explores how soft power is evolving, incorporating digitalisation and climate narratives for deterrence.

3.1. Elements of soft power

  • Culture: This includes cinema, music, literature and sport, such as the global impact of Hollywood, Bollywood and the British Premier League, which has overtaken La Liga, as this competition once did with Italy's Serie A. For example, the World Cup in Argentina (2022) increased its cultural influence in the Global South (Brand Finance, 2022). China exports culture through the Belt and Road Initiative, and increasingly and more forcefully beyond that, in the same way as South Korea and Japan (Zhang, 2025).
  • Political values: The promotion of democracy, human rights and sustainability, such as the American and British narrative that fits in with the neoliberal hegemony of “freedom”, which is somewhat outdated in terms of results in the United Kingdom and the United States, despite the furore with which it is treasured as a great centre of resistance protected by the State that is the Community of Madrid, or the European Union's climate agenda, which reinforces international legitimacy (Nye, 2004; Krüger, 2023). Russia promotes ‘traditional values’ to counter liberalism within, and I would say potentially also to create a doctrine of hegemony, domination and power that fits with the current geopolitical moment and the future of the North America-Europe-Russia space (Kortunov, 2023).
  • Public diplomacy: Public scholarship programmes such as the US Fulbright programme, the Chinese Confucius Institutes or the Institut Français project cultural and educational influence (Nye, 1990). France uses this in Africa for hybrid deterrence (Tertrais, 2024).
  • Global narratives: Campaigns against climate change, such as the Fridays for Future movement, or against disinformation, mobilise global public opinion to put pressure on adversaries (Krüger, 2023). In 2025, digital narratives amplify soft power (Singer & Brooking, 2021).

3.2. Soft power in deterrence

Soft power deters by shaping perceptions and delegitimising the adversary, creating an environment where unwanted actions are politically costly. Historical examples include:

  • US propaganda during the Cold War: Radio Free Europe, Hollywood, and musical and literary trends, as well as art, promoted democratic values, delegitimising Soviet communism and reinforcing the credibility of Western deterrence (Shaw, 2021).
  • Cuba's anti-imperialist narratives: During the US embargo (1960-present), Cuba mobilised support in the Global South with narratives of resistance to imperialism, countering sanctions (Hoffmann, 2022).
  • Campaigns by Greenpeace (1980s-present): Campaigns against industrial fishing in the Arctic combined ecological narratives with international pressure, deterring countries such as Norway from unsustainable activities (Dalby, 2022).

In 2025, soft power becomes digitalised, with China using Weibo for sovereign narratives (Zhang, 2025). Russia employs RT for disinformation, weakening NATO, but achieves this by finding the material and sociological means to do so (Giles, 2025).

3.3. Smart power: integration of hard power and soft power

Smart power, defined by Ernest Wilson (2008) as the strategic combination of hard power and soft power, maximises the effectiveness of deterrence by integrating material capabilities with cultural narratives. From a realist perspective, smart power reflects the need for states to adapt to a multipolar system where influence requires flexibility. Examples include:

  • US containment strategy (1947-1991): The combination of military power (NATO, nuclear triad) with soft power (promotion of democracy through Hollywood and educational programmes) deterred the Soviet Union from expanding its influence (Gaddis, 2005).
  • French cultural diplomacy in Africa: France combines its military presence in the Sahel with cultural initiatives, such as the Institut Français, to deter non-state actors while projecting influence (Tertrais, 2024).
  • China's Belt and Road Initiative: Combines economic incentives (hard power) with cultural soft power (Confucius Institutes) to deter opposition to its global influence (Zhang, 2025). 151

Extensions of Nye see smart power as essential in grey zones, where Russia integrates hybrids with narratives (Wilson, 2008; Giles, 2025).

3.4. Challenges of soft power

Soft power faces several obstacles:

  • Cultural subjectivity: Narratives may not resonate in different cultures. For example, Chinese soft power, based on its ancient culture, faces resistance in the West due to perceptions of authoritarianism (Zhang, 2025).
  • Internal contradictions: Domestic policies, such as polarisation in the United States or repression in China, weaken the credibility of soft power (Brand Finance, 2022).
  • Disinformation: Social media amplifies false narratives, complicating the construction of credibility. An example is Russian propaganda following the invasion of Ukraine (2022), which lost effectiveness due to global condemnation (Singer & Brooking, 2021). However, it remains a form of influence from both the right and the left in the peace narrative: if Europe does not form a federation that allows it to have an army, while the ambitions of the United States do its work by hindering the process in every way possible, then if, when the time comes, Russia finally achieves a political pact with the key to maintaining basic hegemony in defence and security, even if shared with France and the United Kingdom, and if the United Kingdom and France separate, which is better for both the United States and Russia (Brexit), then, thanks to its energy and minerals and its position as a key strategic facilitator, it will be able to maintain its position of strength in the European political landscape.
  • Dependence on hard power: Soft power is most effective when backed by material capabilities. Without hard power, cultural narratives can be perceived as empty (Nye, 2004).

In 2025, digitalisation exacerbates these challenges, with deepfakes eroding trust (Singer & Brooking, 2021). However, soft power remains vital to legitimise hard power in realism.

4. War in the grey zone: China and Russia's strategies

War in the grey zone, defined as the use of ambiguous tactics that avoid open conflict but pursue strategic objectives, is a key component of modern deterrence. In the realist framework, it reflects the need for states to maximise their influence without provoking direct military escalation, especially in a multipolar system (Hoffman, 2018). China and Russia are leaders in this strategy, combining hard power, soft power and hybrid operations to project power and deter their adversaries.

The grey zone exploits legal and regulatory ambiguities, allowing for gradual advances that avoid massive responses (Mazarr, 2015). Comparative studies find that Russia and China adapt the grey zone to their contexts, with Russia being more aggressive and China more economic (Belo & Bérubé, 2019). 20 This section delves deeper into their tactics, comparisons and challenges up to 2025.

4.1. China: grey zone warfare in the South China Sea

China uses grey zone warfare to assert its influence in the South China Sea and deter the United States and its allies without resorting to armed conflict. Its tactics include:

  • Reef militarisation: The construction of artificial islands and military bases in the South China Sea, such as in the Spratly Islands, projects hard power without firing a single shot, deterring countries such as the Philippines and Vietnam from challenging its claims (Hayton, 2022).
  • Ambiguous maritime operations: The use of maritime militias and coast guard vessels to harass foreign fishermen and ships creates a constant presence that discourages resistance (Zhang, 2025).
  • Cultural soft power: Narratives of historical sovereignty, disseminated through Confucius Institutes and public diplomacy in coordination with local actors in strategic locations such as Okinawa and Taiwan, as well as in Central Asia, among others, legitimise Chinese claims in the region (Johnston, 2014).
  • Economic pressure: The Belt and Road Initiative offers economic incentives to Southeast Asian countries, discouraging them from aligning themselves with the United States (Zhang, 2025).

A prime example is the dispute over the Scarborough Shoal (2012), where China used civilian vessels to expel Filipino fishermen, combining hard power (maritime presence) with soft power (historical narratives), without triggering open conflict. From a realist perspective, this strategy reflects the maximisation of relative power in a disputed domain, maintaining credibility without resorting to total war (Hayton, 2022). In 2025, China has intensified its efforts with drones and satellites, integrating space and cyber capabilities (Li, 2024). Chinese perspectives see the grey zone as “unrestricted warfare”, adapting realism to asymmetries (Wu, 2023).

4.2. Russia: hybrid warfare and the grey zone

Russia employs grey zone warfare as part of its doctrine of ‘active deterrence’ (сдерживание активное), which combines military, cyber and disinformation tactics to deter the West and preserve its regional influence (Kortunov, 2023). Its tactics include:

  • Hybrid operations: In Ukraine (2014), Russia combined irregular forces (‘green men’ in Crimea) with disinformation to annex territory without a conventional war, deterring a direct military response from NATO (Giles, 2025).
  • Disinformation: Platforms such as RT and Sputnik spread anti-Western narratives, weakening NATO cohesion and deterring interventions in its sphere of influence by exploiting contradictions and social weaknesses in its targets (Kortunov, 2023).
  • Energy threats: Russia uses its control over natural gas to put pressure on Europe, such as the supply cuts through Nord Stream in 2022, deterring more severe sanctions (McGowan, 2023).
  • Military exercises: Manoeuvres such as Zapad project hard power, reinforcing the credibility of its conventional and nuclear deterrence (Russian Ministry of Defence, 2024).

The invasion of Ukraine (2022) illustrates the limits of grey zone warfare: although Russia achieved initial gains through hybrid tactics, Ukrainian resistance and Western sanctions weakened its credibility, showing that the grey zone is more effective in low-intensity contexts (Giles, 2025). From a realist perspective, Russia's strategy reflects a pragmatic approach to maximising power in a system where Western military superiority limits its options. By 2025, Russia has expanded into cyber warfare, with attacks such as SolarWinds (Nye, 2017).

The United States is following this narrative on certain points, but not all, as NATO continues to exist for the time being. In this regard, it is a mistake to consider this situation to be solely the fault of Trump. No, ‘Trump’ and those who come after him have the hegemony of the Republican Party. Nor can we forget that the current situation is the result of a historical process in which Reagan was the founder and Clinton followed him, closing certain geopolitical files opened by Reagan, after George W. Bush's attempt Bush to control and define a first attempt to control minerals and energy in Iraq and Afghanistan, which could not continue, in the process of Western ‘Sovietisation’, and of the United States in particular, Obama came along and shored up this flaw in the strategy through the expansion of access to energy in the United States and its zone of influence (in the case of Venezuela, remember Trump and his manoeuvre to impose Chevron to the detriment of European and Asian companies, in which, if they can return to Venezuela in some way, the United States will seek to demonstrate that Venezuela ‘is theirs’ in terms of access to and distribution of energy and minerals) in order to distribute it in a game of cooperation and competition with Russia for markets and, following the same logic, to which are added minerals and control of strategic areas both on land and at sea. So do not expect this to be a parenthesis or that the Democrats will not take the same positions, as long as the game of hegemonic transition does not change.

4.3. Comparison and challenges

Both China and Russia use the grey zone to exploit the ambiguities of the international system, avoiding the threshold of open conflict that would trigger massive military responses. However, their approaches differ:

  • China prioritises economic and cultural coercion, supported by gradual military growth, to deter without provoking (Zhang, 2025).
  • Russia combines aggressive tactics (disinformation, hybrid operations) with nuclear and energy threats, taking greater risks of escalation (Kortunov, 2023).

Challenges include:

  • Risk of escalation: Grey zone tactics can be misinterpreted as direct aggression, as in Ukraine (2022), triggering unintended responses (Giles, 2025).
  • International resistance: Global condemnation of Russian actions and Southeast Asian resistance to Chinese claims limit credibility (Brand Finance, 2022).
  • Technological dependence: The effectiveness of the grey zone depends on cyber and disinformation capabilities, which require constant innovation (Singer & Brooking, 2021).

In 2025, the grey zone has been quantified as a framework for measuring hybrid power, with China and Russia leading the way (Small Wars Journal, 2025).

5. Energy deterrence: control of strategic resources

Energy deterrence uses control of energy resources (oil, gas, rare minerals) to influence an adversary's behaviour, either by restricting access or conditioning supply.

In the realistic framework, energy is a critical resource that determines the relative power of states, especially in a context of growing demand and energy transition (McGowan, 2023).

Energy acts as a power multiplier, with Russia and China using control to create asymmetry (Hurst, 2023), and with the United States emerging as another player. This section explores mechanisms, examples and trends up to 2025.

5.1. Fundamentals of energy deterrence

Energy deterrence operates through two main mechanisms:

  • Punitive deterrence: Imposing costs by restricting access to energy resources. Example: Russian gas cuts to Europe via Nord Stream (2022) sought to deter tougher sanctions following the invasion of Ukraine (McGowan, 2023).
  • Deterrence by denial: Controlling strategic resources to limit an adversary's ability to achieve its objectives. Example: China's control of rare earths (97% of global production in 2010) deters dependent countries from challenging its interests (Hurst, 2023).

5.2. Historical examples

  • Oil crisis (1973): OPEC countries, led by Saudi Arabia, imposed an oil embargo on the United States and its allies in response to their support for Israel during the Yom Kippur War, deterring direct intervention in the conflict (Yergin, 2008).
  • Russian energy sanctions (2006-2009): Russia cut off gas supplies to Ukraine to press for debt repayment and political alignment, demonstrating its energy coercion capabilities (McGowan, 2023).
  • Chinese rare earth restrictions (2010): China limited rare earth exports to Japan following a territorial dispute over the Senkaku Islands, deterring Tokyo from escalating the conflict (Hurst, 2023).

In 2025, Russia has used energy against post-Ukraine sanctions, while China dominates minerals for renewables (Hurst, 2023).

5.3. Challenges of energy deterrence

  • Diversification of sources: Target states can diversify their suppliers, as Europe did after the Russian cuts in 2022, increasing gas imports from Norway, the United States and Qatar (McGowan, 2023), although we are now moving towards a similar situation in Europe in a game between two giants in this regard: Russia and the United States.
  • Energy transition: The adoption of renewable energies reduces dependence on fossil fuels, weakening the credibility of energy deterrence (Hurst, 2023).
  • Economic costs: Energy cuts can damage the deterrent, as in the case of Russia after the loss of European markets in 2022 (Giles, 2025).
  • International norms: Energy restrictions can generate global criticism, affecting the legitimacy of the deterrent (McGowan, 2023).

By 2025, energy deterrence will be transformed by the transition to renewable energies and increased demand for rare minerals (lithium, cobalt) for batteries. States that control these resources, such as China and Australia, will have a strategic advantage. In addition, the integration of artificial intelligence technologies into energy management could amplify states' ability to manipulate energy markets, reinforcing deterrence (Hurst, 2023). In realism, this exacerbates competition for scarce resources (Dalby, 2022).

6. Cyber deterrence: foundations and challenges

Cyber deterrence seeks to prevent attacks in cyberspace through the threat of digital retaliation, economic sanctions or conventional measures. From a realist perspective, cyberspace is an emerging domain of power competition, where attribution capability and perceived willingness are crucial (Nye, 2017).

Cyberspace complicates traditional realism by allowing anonymity, favouring revisionist actors (Baliga & Sjöström, 2020). This section examines fundamentals, examples and trends up to 2025.

6.1. Fundamentals

  • Deterrence by punishment: Threatening cyber retaliation or economic sanctions. Example: The US response to the Russian SolarWinds cyberattack (2020) included sanctions and diplomatic expulsions (Nye, 2017).
  • Deterrence by denial: Developing robust cyber defences, such as firewalls and detection systems, to reduce the likelihood of a successful attack (Taddeo & Floridi, 2021).
  • Deterrence by norms: Promote international norms, such as the UN Report of the Group of Governmental Experts on Cyberspace (2025), to deter attacks through multilateral pressure (United Nations, 2025).

6.2. Historical examples

  • Stuxnet attack (2010): The joint cyberattack by the United States and Israel against Iranian nuclear facilities demonstrated the ability to deter through cyber retaliation, delaying Iran's nuclear programme (Nye, 2017).
  • Russian cyberattacks on Ukraine (2015-2022): Russia used cyberattacks against Ukrainian infrastructure (such as the 2015 blackout) to deter Ukraine's integration with the West, although clear attribution limited their effectiveness (Giles, 2025).
  • US cyber sanctions (2021): Following the attack on Colonial Pipeline, the United States imposed sanctions on Russian actors, combining cyber deterrence with economic deterrence (Drezner, 2021).

6.3. Challenges

  • Attribution: Identifying the perpetrator of a cyberattack is technically complex, reducing the credibility of retaliation (Taddeo & Floridi, 2021).
  • Non-state actors: Groups such as Anonymous or state-sponsored hackers operating in the shadows complicate deterrence (Nye, 2017).
  • Escalation: Cyber retaliation can trigger broader conflicts, such as in a scenario of cyberattacks on critical infrastructure (Baliga & Sjöström, 2020).
  • Technological asymmetry: States with advanced cyber capabilities, such as the United States and China, have an advantage, but weaker actors can cause disproportionate damage (Nye, 2017).

In 2025, AI will exacerbate challenges, with sophisticated threats (World Economic Forum, 2025).

Beyond 2025, cyber deterrence will depend on the integration of artificial intelligence to detect and respond to attacks in real time. Multilateral cooperation, such as UN agreements on cybersecurity, will be crucial to establishing norms that reinforce credibility. However, the proliferation of non-state actors and dependence on digital infrastructure will increase the risks of escalation (Taddeo & Floridi, 2021). Russia and China are leading the way in cyber grey zones (Giles, 2025).

7. Climate deterrence: an emerging domain

Climate deterrence uses environmental policies, climate technologies or ecological narratives to influence the behaviour of states or non-state actors. In the realist framework, climate change exacerbates competition for scarce resources (water, arable land), turning climate deterrence into an instrument for protecting national interests (Dalby, 2022).

Climate as a “threat multiplier” extends realism to non-traditional threats (McDonald, 2021). This section explores fundamentals, examples and challenges.

7.1. Fundamentals

  • Deterrence by denial: Protecting key environmental resources to prevent their exploitation by an adversary. Example: The Indus Water Treaty (1960) between India and Pakistan regulates water use, deterring conflict (Dalby, 2022).
  • Deterrence by punishment: Imposing punitive measures, such as trade restrictions on high-emitting countries. The EU's Carbon Border Adjustment Mechanism (CBAM) (2023) is a prime example (Böhringer et al., 2022).
  • Cultural-environmental deterrence: Mobilising global public opinion through ecological narratives, such as international pressure on Brazil over deforestation in the Amazon (Krüger, 2023).

7.2. Historical examples

  • Conflict over the Nile River (20th century): Agreements between Egypt and Sudan (1959) established water quotas, deterring conflicts over this critical resource (Allan, 2001).
  • UN environmental sanctions (1990s): Resolutions to protect Amazonian biodiversity included threats of economic sanctions, a precursor to climate deterrence (Krüger, 2023).
  • Greenpeace campaigns (1980s-present): Campaigns against industrial fishing in the Arctic combined ecological narratives with international pressure, deterring unsustainable activities (Dalby, 2022).

7.3. Case study: the European Union's CBAM

The CBAM, implemented in 2023, imposes tariffs on imports of carbon-intensive goods from countries that do not meet climate standards, incentivising countries such as Turkey to adopt stricter policies. However, it has generated tensions with China and India, which perceive it as a form of protectionism, reflecting power competition in the realist framework (Böhringer et al., 2022). The credibility of the CBAM depends on multilateral cooperation and the EU's ability to absorb the economic costs of trade retaliation. In 2025, CBAM has expanded, integrating soft power narratives (Krüger, 2023).

7.4. Challenges

  • Attribution: Identifying responsibility for climate change is difficult, as the impacts are global and cumulative (Dalby, 2022).
  • Asymmetry of interests: Developing countries prioritise economic growth over emissions reduction, reducing the credibility of climate threats (Böhringer et al., 2022).
  • Risk of escalation: Climate sanctions can trigger economic tensions, as in the case of the CBAM (Krüger, 2023).
  • Ethics: The manipulation of environmental resources can exacerbate inequalities, affecting vulnerable populations (Dalby, 2022).

Beyond 2025, climate deterrence will gain relevance due to intensifying conflicts over environmental resources. Technologies such as geoengineering (carbon capture, solar radiation management) could become deterrent tools, although they pose ethical and technical risks. Ecological narratives, amplified by movements such as Fridays for Future, will reinforce cultural-environmental deterrence, aligning themselves with soft power (Krüger, 2023). In realism, climate exacerbates anarchy as the basis of international relations, requiring strategic adaptation (Dalby, 2022). 110

8. Biotechnological deterrence: an ethically complex domain

Biotechnological deterrence uses the threat of biological weapons or genetic technologies to deter, although it is limited by international norms and ethical dilemmas. In the realist framework, it reflects competition for power in an emerging domain, where ambiguity can be a strategic tool (Koblentz, 2017).

Advances such as CRISPR have raised the potential, but also the ethical risks (Esvelt, 2023). This section explores fundamentals, examples and trends.

8.1. Fundamentals

  • Punitive deterrence: Threatening to use biological weapons, such as anthrax, to inflict catastrophic harm. The Soviet Biopreparat programme (1970s-1980s) is a historical example (Leitenberg & Zilinskas, 2012).
  • Deterrence by denial: Developing biological defences, such as vaccines or detection systems, to reduce the likelihood of a successful attack. The US BioShield Project (2004–present) illustrates this approach (Gottron, 2020).

8.2. Historical example

The Soviet Biopreparat programme developed biological agents as a deterrent against the United States, using ambiguity to project a credible threat without openly violating the Biological Weapons Convention (1972) (Leitenberg & Zilinskas, 2012).

8.3. Challenges

  • Attribution: Identifying the perpetrator of a biological attack is complex, reducing the credibility of retaliation (Lentzos, 2022).
  • International norms: The Biological Weapons Convention prohibits the development of these weapons, limiting explicit threats (Koblentz, 2017).
  • Risk of escalation: A biological attack could trigger global pandemics, undermining the deterrent (Esvelt, 2023).
  • Ethics: The development of biological weapons is widely condemned, undermining the legitimacy of the deterrent (Lentzos, 2022). Ethics include inequalities and dual use (Bügl et al., 2023).

Beyond 2025, advances in biotechnology, such as gene editing (CRISPR), could expand biotechnological deterrence capabilities, but also increase proliferation risks. International cooperation to regulate these technologies will be crucial to prevent a biological arms race (Bügl et al., 2023). In realism, this represents, once again, a new domain of anarchy (Koblentz, 2017), in which conventional states, I conclude, will not be able to act effectively on their own, requiring the scaling up of core power through federations that can muster sufficient means and resources, not only in this scenario, but in all scenarios.

9. Space deterrence: the domain of the future

Space deterrence seeks to protect space assets, such as satellites, through the threat of retaliation or denial of benefits. In the realist framework, space is a critical domain for power projection, as satellites are essential for communication, navigation and military reconnaissance (Yagües Palazón, 2018).

Space militarisation accelerates in 2025, with ASAT proliferating (Secure World Foundation, 2025). ASAT stands for Anti-Satellite and refers to weapons or systems designed to destroy or disable satellites in orbit. China, along with the United States, Russia and India, is one of the countries known to be developing and testing this type of weaponry.

This section examines fundamentals, examples and trends.

9.1. Fundamentals

  • Deterrence by punishment: Threatening to destroy the adversary's space assets, such as the 2007 Chinese ASAT test, which demonstrated its ability to neutralise satellites (Li, 2024).
  • Deterrence by denial: Developing space defences, such as laser systems or cyber defences, to protect one's own assets (Harrison, 2024).

9.2. Historical example

The 2007 Chinese ASAT test, which destroyed one of its own satellites, sent a clear signal to the United States about its ability to threaten space assets, reinforcing its credibility as a deterrent (Li, 2024).

9.3. Challenges

  • Proliferation of actors: The entry of commercial actors, such as SpaceX, complicates the attribution and regulation of space (Johnson-Freese, 2023).
  • Debris risk: ASAT attacks generate debris that threatens all actors, reducing the credibility of retaliation (Grego, 2017).
  • Technological costs: The development of space weapons requires massive investments, limited to major powers (Harrison, 2024).
  • Ultimately, this brings us closer to the point where the amount of space debris is so high that it causes chain collisions and makes the use of certain orbits difficult or impossible: in other words, we will reach the Kessler Syndrome, also known as the Kessler effect or cascade, which describes a catastrophic scenario where the accumulation of space debris, when colliding with each other, generates more debris, increasing the risk of new collisions in a destructive cycle. Kessler syndrome, which is a growing concern due to the increase in space debris, includes failed satellites, rocket debris and other abandoned objects. These pieces, some the size of a car and others as small as a grain of sand, travel at very high speeds, turning even the smallest objects into dangerous projectiles. The Kessler scenario could render certain orbits, especially low Earth orbits (LEO), unusable due to the high risk of collisions, causing many vital applications, such as communications, navigation, weather observation and scientific research, which depend on satellites in orbit, would certainly be compromised, causing damage to all devices that use them. In addition, the accumulation of space debris hinders the launch of new satellites and makes space exploration in general more difficult. For these reasons, the University of Arizona (United States) and the ESA (European Space Agency) are insisting on the development of technologies for its clean-up and mitigation, estimating that there are around 900,000 objects larger than one centimetre orbiting the Earth, in addition to other debris. According to the UN, this fact endangers future missions and even terrestrial communications.

Beyond 2025, the militarisation of space will intensify with the development of non-kinetic weapons (lasers, cyberattacks) and the proliferation of commercial constellations.

International cooperation to establish space rules will be essential to prevent an arms race (Johnson-Freese, 2023). Russia and China are leading the way, with Russian nuclear ASATs posing a threat (National Security Space Association, 2024).

10. Doctrinal evolution of deterrence: a comparative analysis

The evolution of deterrence among major powers reflects their strategic priorities, capabilities and historical contexts, aligning with the realist logic of power maximisation.

10.1. United States

As a global hegemon, the United States has developed a doctrine of deterrence that integrates hard power, soft power and smart power to maintain its dominance in the international system.

During the Cold War, the doctrine of ‘massive retaliation’ (1950s) evolved into ‘flexible response’ (1970s), which combined nuclear and conventional capabilities to deter the Soviet Union (Freedman, 2004).

The nuclear triad (Minuteman III ICBMs, Ohio submarines, B-2 bombers) ensured mutually assured destruction, as seen in the Cuban Missile Crisis (1962) (Jervis, 1985).

In the post-Cold War era, the United States broadened its focus to non-state and cyber threats, with economic sanctions as a key tool, as in the case of Iran (2018-2025) (Drezner, 2021).

Under the two Trump administrations (2017-2025), economic deterrence took centre stage with tariffs on China and sanctions on Russia, although isolationism weakened US soft power (Abdelhalim, 2025). US soft power, based on Hollywood, programmes such as Fulbright and democratic narratives that are increasingly less credible, and which had historically been robust, has been eroded by internal polarisation and perceptions of hypocrisy (e.g. on human rights, but the list is only growing) (Brand Finance, 2022).. By 2025, the United States is adapting its doctrine to address emerging threats, such as cyberattacks and hypersonic weapons, through the integration of artificial intelligence and the U.S. Space Force (Lieber & Press, 2023).

10.2. Soviet Union/Russian Federation

The Soviet Union based its deterrence on nuclear hard power, with a robust triad (SS-18 ICBMs, Delta submarines, Tu-95 bombers) that ensured parity with the United States during the Cold War.

The Missile Crisis (1962) and the Euromissile Crisis in the context of NATO's Able Archer exercise (1983) illustrate the credibility of its nuclear deterrence (Jervis, 1985; Freedman, 2004).

However, its soft power was limited by its authoritarian image, with exceptions such as its support for anti-imperialist movements in the Global South (Nye, 2002).

After the dissolution of the USSR, Russia adopted a doctrine of “active deterrence”, combining hard power (modernisation of Topol-M missiles, Borei submarines, Tu-160 bombers), hybrid tactics (disinformation, cyberattacks) and energy deterrence (control of natural gas) (Kortunov, 2023). The invasion of Ukraine (2022) weakened its soft power due to global condemnation, but its economic resilience, supported by alliances with China and India, partially offset Western sanctions (Giles, 2025). Military exercises such as Zapad and platforms such as RT reinforce its credibility, although perceptions of internal instability limit its effectiveness (Brand Finance, 2022). By 2025, Russia has integrated tactical nuclear weapons for controlled escalation (Fenenko, 2021).

10.3. China

China has developed a doctrine of ‘minimal deterrence’ (威慑最小化) to protect national interests, such as Taiwan and the South China Sea, combining hard power (DF-41 missiles, Jin submarines, H-6N bombers), soft power (Confucius Institutes, historical narratives) and economic deterrence (Belt and Road Initiative). (Wu, 2023).

During the Cold War, its nuclear deterrence was limited, but military modernisation since the 2000s has strengthened its credibility (Li, 2024). Grey zone warfare, such as the militarisation of reefs in the South China Sea, deters adversaries without provoking open conflict (Hayton, 2022).

China's soft power, based on its ancient culture and donations of COVID-19 vaccines, coupled with new resources, has gained influence in the Global South but faces resistance in the West due to perceptions of authoritarianism (Brand Finance, 2022). However, it is growing through anime, graphic adventures, Labubu, Mokoko and other resources. By 2025, China is expanding its energy (rare earth control) and cyber deterrence, reinforcing its position as a multipolar power (Zhang, 2025).

10.4. United Kingdom

The United Kingdom combines nuclear deterrence (Vanguard submarines with Trident missiles) with cultural and diplomatic soft power to reinforce its role in NATO and the Commonwealth. During the Cold War, its deterrence was subordinate to that of the United States, but it maintained a limited nuclear triad (Freedman, 2004).

After Brexit, British soft power, based on the BBC, universities and pop culture, partially offset the loss of influence in the EU (Brand Finance, 2022). Sanctions against Russia (2022) and cooperation with the Commonwealth illustrate its smart power approach, combining economic sanctions with narratives defending the liberal order (Giles, 2025). Towards 2025, the UK is investing in cyber defence and space technologies to maintain its credibility (Harrison, 2024).

10.5. France

France bases its deterrence on dissuasion nucléaire, which prioritises “nuclear sufficiency” to guarantee strategic autonomy, with a limited triad (Triomphant submarines, Rafale fighters with ASMP-A missiles) (Poirier, 1972). During the Cold War, its independence from NATO reinforced its credibility as a middle power (Tertrais, 2024). In the post-Cold War era, France has expanded its soft power through Francophonie and operations in the Sahel, combining military presence with cultural initiatives (Institut Français) (Tertrais, 2024).

The integration of climate deterrence (CBAM) and cyber deterrence reflects its adaptation to emerging threats (Böhringer et al., 2022). However, colonial perceptions in Africa limit its soft power (Tertrais, 2024). In 2025, France proposes extended European deterrence (Tertrais, 2024).

10.6. India

India adopts a doctrine of ‘minimum credible deterrence’ to counter China and Pakistan, underpinned by a developing nuclear triad (Agni-V missiles, Arihant submarines, Rafale fighter jets) (Basrur, 2023). The Pokhran-II nuclear tests (1998) established its status as a nuclear power, deterring Pakistan after the Kargil War (1999) (Sagan, 2009). Clashes with China in Ladakh (2020) and restrictions on Chinese apps (2020) illustrate its conventional and economic deterrence (Kumar, 2024). India's soft power, based on Bollywood, yoga and a diaspora of 30 million, amplifies its influence in the Global South, as seen after the 2022 World Cup (Brand Finance, 2022). However, asymmetry with China and internal polarisation limit its credibility (Kumar, 2024). In 2025, India integrates climate policy due to water disputes (Dalby, 2022). US actions bring the Indian pole closer and strengthen it in the multipolar world, and US dreams of controlling it remain just that for now, but could turn into a nightmare if they do not understand once and for all what and who India is.

10.7. Pakistan

Pakistan employs ‘asymmetric deterrence’ to counter India's conventional superiority, based on a tactical nuclear arsenal (Nasr missiles) and anti-Indian narratives (Khan, 2023). The Chagai-I nuclear tests (1998) were a response to India, establishing a regional MAD balance (Sagan, 2009). The nuclear threat following the Pulwama attack (2019) deterred India from military escalation, although it led to international sanctions (Khan, 2023). Pakistan's soft power, based on Islamic narratives, resonates in the Muslim world, but perceptions of internal instability and support for terrorism limit its credibility (Brand Finance, 2022). Economic dependence on China (CPEC) and the IMF weakens its economic deterrence (Ahmed, 2025).

10.8. India-Pakistan dynamics

The India-Pakistan rivalry is a paradigmatic case of deterrence in a context of high regional tension. Both maintain nuclear postures (India with ‘no first use’, Pakistan with ambiguity) that create a regional MAD equilibrium (Sagan, 2009). India has economic and cultural advantages, but Pakistan compensates with Chinese support and asymmetric tactics (Kumar, 2024; Ahmed, 2025). The Indus Water Treaty (1960) regulates water use, but climate change increases the risk of conflict, making climate deterrence an emerging domain (Dalby, 2022). In 2025, the emerging triad raises the risk of crisis (Khan, 2023).

By 2025, deterrence faces a complex landscape due to multipolarity, disruptive technologies and environmental dynamics:

  • Disruptive technologies: Hypersonic weapons, artificial intelligence, biotechnology and space capabilities are redefining deterrence, requiring constant modernisation (Lieber & Press, 2023; Bügl et al., 2023).
  • Multipolarity: The rise of China, India and blocs such as the BRICS challenges Western hegemony, requiring smart power strategies (Åslund, 2023).
  • Climate and energy deterrence: Competition for environmental and energy resources (water, rare earths, lithium) will make these domains critical areas of deterrence (Dalby, 2022; Hurst, 2023).
  • Grey zone: China and Russia's hybrid tactics will continue to challenge international norms, requiring coordinated responses (Hoffman, 2018).

The ethical challenges are significant:

  • Nuclear deterrence: The threat of mass destruction poses moral dilemmas due to its catastrophic impact (Holmes, 1989).
  • Biotechnological deterrence: The development of biological weapons violates international norms and poses proliferation risks (Lentzos, 2022).
  • Climate deterrence: Manipulation of environmental resources can exacerbate global inequalities (Dalby, 2022).
  • Economic and energy deterrence: Sanctions and energy restrictions cause civilian suffering, as in Iraq (1990–2003) or Ukraine (2022) (Gordon, 2010; McGowan, 2023).
  • Soft power and the grey zone: The manipulation of narratives and disinformation pose ethical risks, especially in authoritarian regimes (Nye, 2002; Singer & Brooking, 2021).

Ethics in biotechnology includes dual use and inequalities (Jagota, 2025). 93

13. European deterrence: credibility vis-à-vis Russia in a context of shared interests between Moscow and Washington

European deterrence, understood as the ability of the European Union (EU) and its Member States to project credible threats that deter aggression, for example from Russia, faces profound structural challenges in an international system where Russia and the United States may share common strategic interests, such as containing China or stabilising and managing global energy routes, as well as strategic minerals and the security of trade and logistics routes.

This scenario applies directly to the conflict in Ukraine, but also to potential flashpoints such as Moldova (with the enclave of Transnistria), Georgia, the Baltic States (Estonia, Latvia and Lithuania) or even Belarus, if a change in Lukashenko's leadership or his succession were to move Minsk away from Moscow towards a more pro-European orientation, something that was possibly undermined by the interference of Poland and Lithuania (which are not exactly Brzezinski or Litvinov, respectively) in the process that Lukashenko was following in moving away from Moscow, which was a breach of Moscow's red line stretching from Kaliningrad to Transnistria and Crimea.

In the realistic framework, the credibility of European deterrence depends on the intersection of capability, will and communication, but it is undermined by historical dependencies on the United States, military and technological gaps, and internal divisions in economic, industrial and defence policies (Waltz, 1979; Mearsheimer, 2001). Added to this is the post-Cold War process that led Russia and the United States to define amity lines and red lines in the isthmus of the European peninsula, while Russia has been seeking for 35 years to enter into a political agreement underpinned by several pillars of European security and beyond, from a position of intended hegemony in security and defence in conventional and unconventional means, with an evident pact of entente with France and the United Kingdom at the continental European level, and with the United States outside Europe, which in turn finds itself immersed in the situation of understanding that its geopolitical survival depends on controlling Europe by adapting the Russian means of approach from the Soviet era, but adapted to US strategic needs.

The fact that the United States has been obsessed with keeping a European federal process with a European army under control has been the key element of tacit understanding and favouritism towards the Russian European strategy, since without a European army in a federal Europe, the political and security pact is established on terms that are more favourable and strategic for Russia. And this, with all due respect to propagandists and ideological diehards of Cold War fantasies rather than realities, is what has existed, exists and will continue to exist until it is resolved: this is what has happened in Ukraine (2014, 2022), Georgia (2008), Belarus (2021, resolved with the possible help of the strategic stupidity of Poland and Lithuania in favour of Moscow), Transnistria (1990-1992), the general scenario in the South Caucasus as far as Russian interests are concerned, among other actors, or the Chechen war and the pact that turned Chechnya into a principality under the rule of political Islam, the same Islam that Moscow claimed to be fighting in Syria alongside Iran (sic), until events came to a head in December 2024 (for more information, see this link to a recent publication).

This analysis examines, in this part, the historical context, current vulnerabilities and potential for optimising deterrence, incorporating a SWOT analysis (strengths, weaknesses, opportunities and threats) based on trends up to August 2025.

To delve deeper into this dimension, it is relevant to integrate the contributions of Franz-Stefan Gady, an analyst associated with the International Institute for Strategic Studies (IISS) and the Centre for a New American Security (CNAS), whose work focuses on modern warfare, hybrid deterrence and military dynamics in Eastern Europe. Gady has consistently argued that European deterrence against Russia requires a radical transformation, moving away from US-dependent approaches and towards autonomous capabilities that prioritise mobility, resilience and strategic credibility.

In his analysis, credibility is not based on static or symbolic deployments, but on the ability to generate unacceptable costs for Moscow through a concentrated and rapidly deployable ‘mass of manoeuvre’ capable of responding to threats in Ukraine, the Baltics or Georgia without committing key units to prolonged missions (Gady, 2025a).

This perspective highlights Europe's historical failures in conflicts such as the Balkans or Georgia, where a lack of unity and logistical dependence on Washington diluted perceived resolve, allowing Russia to exploit internal divisions.

Gady criticises the emphasis on troop deployments in Ukraine as an ‘illusory solution’ that ignores lessons from the Cold War and recent conflicts, arguing that such forces would tie up European resources without effectively deterring Russia, especially in a context where Putin perceives any Western presence as a provocation to his sphere of influence. Instead, he proposes a ‘proportional deterrence’ approach that integrates mechanised forces with cyber and intelligence capabilities, inspired by initiatives such as the NATO Readiness Initiative, but adapted to European autonomy (Gady, 2025a).

With regard to Ukraine, Gady emphasises that Europe must clarify whether the country is essential to its continental security; if so, it must invest in a rapid reaction force of at least 25,000-30,000 troops, with rotations reaching 90,000, combining traditional peacekeeping forces from the Global South in demilitarised zones with robust European brigades equipped with tanks.000 troops, with rotations reaching 90,000, combining traditional peacekeeping forces from the Global South in demilitarised zones with robust European brigades equipped with tanks, artillery and air defences (Gady, 2024).

This strategy would prevent the erosion of credibility due to war fatigue or political divisions, such as those observed in France and Germany post-2022.

As for potential scenarios such as Moldova or Belarus, Gady warns that a pro-European shift in Minsk could trigger Russian interventions similar to Crimea, requiring Europe to develop capabilities for hybrid operations that combine conventional deterrence with cyber warfare, without relying on US support that could be conditioned by shared interests between Washington and Moscow (Gady & Kofman, 2023).. His work on Ukraine's attrition strategy against Russia highlights how Europe could learn from Kiev in integrating drones and electronic warfare to deny Russian advances in the Baltics or Georgia, transforming deterrence from defensive to limited offensive (Gady, 2023).

Gady quotes several sources that reinforce his realistic view of European deterrence. Among them, he highlights Jim Mattis, former US Secretary of Defence, for his leadership in the 2018 NATO Readiness Initiative, which proposed deploying 30 battalions, squadrons and ships in 30 days, a model that Gady sees as the basis for an autonomous European ‘maneuvering mass,’ praising its focus on speed and concentration of forces (Gady, 2025a).

He also praises General Mikhail Kostarakos, former chair of the EU Military Committee, for his accurate diagnosis of the lack of European ‘strategic enablers,’ such as logistics and intelligence, which Gady uses to argue against hasty deployments in Ukraine (Gady, 2025a)..

The International Institute for Strategic Studies (IISS), where Gady is an associate, is cited positively for its data on Polish military capabilities (14 brigades), which serve as an example to reinforce Poland as a defensive pivot against Russia (Gady, 2025a).

In addition, Gady favourably mentions Emmanuel Macron for his initiative to form European coalitions to station forces in Ukraine, seeing it as a step towards strategic autonomy, although he warns of its limitations without logistical support (Gady, 2024).

Italian Defence Minister Guido Crosetto is praised for his willingness to participate in peacekeeping missions, highlighting Italy's commitment as a model for coalitions of 5-8 nations (Gady, 2024).

Gady also cites positively reports from the Congressional Research Service (CRS) on systems such as Strategic Mid-Range Fires, praising their usefulness in adding layers of conventional deterrence in post-ceasefire scenarios, even if Europe must develop autonomous equivalents (Gady, 2024).

The key is that Europe must adopt a “combined warfare” approach to credibility against hybrid threats (Gady & Kofman, 2023; Gady & Gressel, 2025), and move forward on the path towards the EU being able to mitigate vulnerabilities by prioritising investments in mobility and resilience, transforming its stance from reactive to proactive in a multipolar system.

13.1. Historical context and strategic dependencies

European deterrence, understood as the ability of the European Union (EU) and its member states to project credible threats that deter Russian aggression, faces profound structural challenges in an international system where Russia and the United States may share common strategic interests, such as containing China or stabilising global energy routes.

This scenario applies directly to the conflict in Ukraine, but also to potential flashpoints such as Moldova (with the Transnistria enclave), Georgia, the Baltic states (Estonia, Latvia and Lithuania) or even Belarus, if a change in Lukashenko's leadership or his succession were to move Minsk away from Moscow towards a more pro-European orientation.

In the realistic framework, the credibility of European deterrence depends on the intersection of capability, will and communication, but is undermined by historical dependencies on the United States, military and technological gaps, and internal divisions in economic, industrial and defence policies (Waltz, 1979; Mearsheimer, 2001). This analysis examines the historical context, current vulnerabilities and potential for optimising deterrence, incorporating a SWOT (strengths, weaknesses, opportunities and threats) analysis based on trends up to August 2025.

European deterrence has evolved in a context marked by conflicts that highlight its dependence on the United States. The war in Transnistria (1992) illustrated post-Soviet instability in Moldova, where Russia maintained influence through peacekeeping forces, while Europe lacked unified mechanisms to intervene (King, 2000). The Balkan wars (1991-2001) exposed internal divisions within the EU, with NATO-led interventions dependent on US intelligence and logistics, undermining European credibility as an autonomous actor (Daalder & O'Hanlon, 2000). The conflict in Georgia (2008) demonstrated Russia's ability to act quickly in its ‘sphere of influence’, with Europe responding with limited sanctions and French mediation, but without credible military deterrence (Asmus, 2010). In Ukraine, since the annexation of Crimea (2014) and the large-scale invasion (2022), the EU has provided humanitarian and economic aid, but military deterrence has depended on US supplies, with Washington providing 75% of total military aid until 2025.

Broader scenarios, such as Libya (2011), where French- and British-led intervention required US logistical support; the Palestinian-Israeli conflict, influenced by energy routes in the Eastern Mediterranean; or the Gulf Wars (1991, 2003), highlight Europe's dependence on US maritime security.

The EU does not autonomously sustain its vital routes, such as the Strait of Hormuz or the Suez Canal, delegating this task to the US Navy. This allows China, in this context, to pursue its strategic imperative following the announcement of its pivot towards Asia and the need to secure the flow of trade, energy and minerals through the Indo-Pacific bottlenecks, expanding its influence through the Belt and Road Initiative, potentially putting pressure on Europe in the Indo-Pacific (European Commission, 2021). To this must be added all the bottlenecks that remain within the space between the Black Sea, the Suez Canal and the Strait of Gibraltar, with support from the Macaronesia islands and the Gulf of Guinea, the GIUK gap and the Danish straits. This dependence is exacerbated by the military gap: Europe lacks a comprehensive range of weapons, intelligence and logistics systems, lessons not learned from 35 years of conflict, from the Balkans to Ukraine (Bruegel, 2025), compounded by the technology gap.

13.2. Structural vulnerabilities and internal divisions

The credibility of European deterrence is eroded by institutional and economic factors. The euro functions as a monetary unit, but the absence of fiscal and banking union limits the ability to finance collective defences, with fragmented national budgets (European Central Bank, 2023). The EU is not a federation with full economic and industrial integration, lacking cross-cutting policies on technology and defence, resulting in duplication and inefficiencies (European Defence Agency, 2024). This triggers arms spending and the inefficiency of European military action, benefiting the arms industry without addressing the vital deficiencies identified over the past 35 years. There is no unified European army with comprehensive planning for high-intensity conflicts, dependent on NATO and, therefore, on the United States (NATO, 2025), which above all does not want to see a political federation in Europe, a banking, monetary and fiscal union, or a European army that guarantees the security of all routes and access to all markets and resources. Russia counts on this for its own logic and ambitions.

The countries of Eastern Europe (Poland, Hungary, the Czech Republic, Slovakia, Romania, Bulgaria, the Baltic states) prioritise US acquisitions. Added to this is the influence of failures in Iraq and Afghanistan, and Obama's transition of the United States as an energy power, competing or cooperating with Russia for European markets (U.S. Energy Information Administration, 2025), which, particularly with the ambitions of Poland and Lithuania, have so far been one of the basic gateways in Europe to compete with Russia in this space and on these terms, which date back to the Soviet era and have continued with the Russian Federation.

This sustains the US arms industry, with 63% of EU military budgets earmarked for US companies in 2024, including AI adapted to defence. Despite a possible US pact with Russia, these countries are demanding more US purchases, fearing abandonment (The Guardian, 2025), which has also come about because of US strategic needs and the way Russia fits into them. Obviously, once part of the work has been done, Poland and Lithuania find themselves sidelined, including from the 18 August meeting in Washington D.C., which Lithuania understands and is now trying to repair its relations with China, which were particularly damaged in November 2021... because I fear that neither Lithuania nor Poland are Russia, nor all that Russia can offer to the US strategy as a whole.

To quantify this: from 1990 to 2025, Eastern Europe has imported US arms worth an estimated $150-200 billion (SIPRI Arms Transfers Database, 2025), with peaks post-2014: Poland spent $12 billion on F-35s and Patriots (SIPRI, 2025); the Baltics spent $5 billion on HIMARS and Javelins. In energy, agreements with US companies exceed $100 billion, including LNG ($64 billion in 2024 for the EU, 40% to Eastern Europe) and nuclear (Westinghouse in Poland and the Czech Republic, $20 billion) (Reuters, 2025; IEEFA, 2025). This prioritises the United States over European companies such as EDF and Siemens, weakening industrial integration, and part of that money comes from the European Union's own plans.

Russian-German energy interests, such as Nord Stream, have had a negative influence: Germany depended on Russian gas (55% of imports pre-2022), delaying sanctions and undermining European unity against Russia (Clean Energy Wire, 2024). This created divisions, with the East viewing Germany as complacent, eroding collective credibility (OSW, 2022).

13.3. The Azerbaijan-Armenia bottleneck and its implications

Additionally, the United States has created a land ‘bottleneck’ in the South Caucasus through its role in the Armenia-Azerbaijan peace agreement (August 2025), establishing the ‘Trump Route’ (Zangezur corridor), which connects Azerbaijan with Nakhchivan via Armenia, operated under Armenian sovereignty but with exclusive US development rights for 99 years (Reuters, 2025). This affects land routes from Central/Eastern Asia, the South Caucasus and Turkey to Europe, boosting the Middle Corridor and the Belt, but excluding Russia and Iran, reducing their influence on energy and trade transit (Al Jazeera, 2025). For Europe, it offers route diversification but increases dependence on the United States for security, potentially weakening autonomous deterrence if Washington prioritises shared interests with Moscow (SpecialEurasia, 2025).

13.4. SWOT analysis to optimise European deterrence

A comprehensive study of European deterrence reveals:

  • Strengths: Combined economy of $18 trillion (2025), larger than Russia ($2 trillion), allowing investment in dual-use technology (AI, cyber); cultural and normative soft power to delegitimise Russian aggression; alliances such as NATO and partnerships with the Indo-Pacific (European Commission, 2025).
  • Weaknesses: Budgetary fragmentation (EU defence spending: 1.9% of GDP vs. 3.5% in the United States); dependence on US arms imports (64% NATO-Europe); lack of fiscal union for sustainable financing; gaps in intelligence and logistics (Bruegel, 2025; Taurillon, 2025). Russia is in an extraordinary position in the military-industrial sector.
  • Opportunities: Increased post-Ukraine defence spending (17% in 2024, $693 billion including Russia); industrial integration via the European Defence Fund ($8 billion 2021-2027); energy diversification (REPowerEU, reducing Russian dependence to 10%); cooperation with the United States for technology transfer without total dependence (SIPRI, 2025; Clean Energy Wire, 2024).
  • Threats: Shared interests between the United States and Russia (e.g., containing China), reducing support for Ukraine; potential Russian escalation in the Baltics/Moldova; Russian hybrid cyber/energy warfare; Chinese influence on maritime routes (ISS Europe, 2025; Taurillon, 2025).

To optimise, the EU must:

1) Create a European army with unified command and integrated budgets (minimum 2% of GDP, which in my estimate amounts to around €430 billion per year);

2) Advance fiscal/banking union for financing;

3) Prioritise European acquisitions (e.g. FCAS, MGCS). Ultimately, euros should stay in Europe, which includes stopping sending money en masse to US financial centres, but this requires a European federal power and a credible European project to invest in;

4) Develop autonomous intelligence and cyber defence;

5) Diversify energy/trade routes, including the Caucasus;

6) Strengthen smart power for anti-Russian narratives (ECFR, 2025; RAND, 2025).

This would increase credibility, reducing risks in scenarios such as Belarus or Georgia.

14. Conclusion

Deterrence, in a realistic framework, is a dynamic instrument of power that reflects the competition for survival and hegemony in an anarchic international system.

Credibility, underpinned by capability, willingness and communication, is at the core of its effectiveness, applying in domains as diverse as nuclear, conventional, economic, energy, cyber, space, biotechnology and climate.

Hard power provides the material basis, while soft power and smart power amplify influence through cultural narratives and hybrid strategies.

War in the grey zone, led by China and Russia, illustrates the evolution of deterrence towards ambiguous tactics that avoid open conflict.

The perspectives of the United States, Russia, China, the United Kingdom, France, India and Pakistan show how deterrence strategies are adapted to historical and regional contexts, integrating hard power and soft power to maximise relative power.

By 2025, deterrence will face unprecedented challenges due to multipolarity, disruptive technologies and competition for environmental and energy resources. The integration of artificial intelligence, multilateral cooperation and cultural narratives will be crucial to maintaining credibility without provoking unnecessary escalations. However, the ethical dilemmas associated with nuclear, biotechnological, climate and energy deterrence require a balance between national security and global responsibility. Ultimately, deterrence will remain a strategic art that combines power, perception and persuasion in a world where competition defines international relations. This evolution underscores the resilience of realism as an analytical lens, adapting to new domains while maintaining its focus on power as the primary currency (Mearsheimer, 2014).

In this scenario, Europe must start from a federal position that transforms its basic pillars in terms of industry, industrial capacity, control of supply chains, control of trade routes, and control of supply routes, and have the means for a structured, organised and credible deterrence, adequately identifying global actors, their interests, and anticipating their next moves.

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