Post-American Europe: strategic autonomy and the transformation of the transatlantic relationship

Abstract

As debates over a “Post-American Europe” rise and the Atlantic relationship declines, we need to answer a key question: is Europe transitioning towards true strategic autonomy, or is it merely adapting to a declining institutional framework?

This article argues that the view of a true “Post-American Europe” overstates the degree of the current situation, and that the EU is in the process of adapting to a new world order. The analysis of the three main theories of Hegemonic Stability, Complex Interdependence, and the Liberal Leviathan is crucial to understanding the European strategy of adaptation. By treating the American cutback as an independent variable and the European strategic autonomy as the dependent variable influenced by the international environment, the degree of EU cohesion and the defence capacity, it is easily understandable how strategic autonomy has emerged not as a rupture, but as a resilience strategy designed to prevent uncertainty while preserving the foundations of transatlantic security. 

Key Words

Strategic autonomy; Adaptation; Structural transformation; Hegemony; Resilience; Interdependence

I. Introduction

For several decades, European security has been endorsed by American supremacy. The post-WW2 Atlantic order constituted a perfect example of hegemonic stability, deeply rooted in the North Atlantic Treaty Organization (NATO), U.S. deployment and economic interdependence. Yet, debates about a “Post-American Europe” have recently intensified. The United States’ strategic attention has shifted towards the Indo-Pacific area, and domestic policy has become volatile regarding alliance commitments. Simultaneously, Europe has faced a changing international scenario with a revisionist Russia, a growing China and internal fragmentation. 

The question is no longer whether the transatlantic relationship is changing; it has become a question of how and to what extent. Is Europe structurally transitioning towards strategic autonomy, or is it merely adapting to a declining Atlantic framework? 

This article argues that the notion of “Post-American Europe” overstates the degree of structural transformation currently in effect. While American strategy and policies have intensified European debates over autonomy, the empirical evidence doesn’t demonstrate a systemic rupture yet. Instead, European responses reflect a recalibration within an enduring framework of institutionalized interdependence.

Secondly, this article highlights the need to understand European strategic autonomy as incremental and specific to certain dimensions rather than as a binary shift towards independence. The evidence of Europe remaining embedded in NATO’s structure and U.S. capabilities in the military sphere, opposed to resilience-building in economic and industrial policies under the banner of Open Strategic Autonomy (OSA), suggests a pattern of adaptation within the system. 

The structure of the article reflects its analytical progression. The first section establishes the theoretical bases by examining the Hegemonic Stability Theory, Ikenberry’s concept of “constitutional order” in the Liberal Leviathan, and the Theory of Complex Interdependence. The second module operationalizes the concept of strategic autonomy and identifies measurable dimensions across the different domains. The third and fourth empirical units assess recent initiatives in light of these dimensions to then link the findings to the initial theoretical framework. The conclusion finally evaluates whether Europe is genuinely transitioning toward a “Post-American” order or adapting within a resilient Atlantic system.  

II. Hegemonies and Institutional Order 

The Hegemonic Stability Theory, originated in the 1970s, provides the basis to evaluate the idea of a “Post-American Europe”. In its classical formulation, associated with Charles Kindleberger’s analysis of the 1930s economic collapse, the main argument states that the international system is most likely to remain stable with a single dominant State controlling the economy, the military and the main political power. The Hegemon therefore secures trade routes, stabilizes the monetary system and provides security that benefits the entire international structure (the key example for this theory being Britain in the 19th century) (Webb & Krasner, 1989).

Applying the same reasoning to the U.S. after 1945, we can easily identify three core pillars supporting Europe: deterrence because of nuclear power, pre-positioned conventional forces to deter Soviet and later Russian attacks, and institutional leadership through NATO. This structure temporarily eliminated collective action problems between European states and provided enough security to develop economic integration. However, it also significantly lowered the incentive for autonomous stability. 

Nevertheless, later research somewhat opposes the Hegemonic Stability Theory applied to the U.S., arguing the postwar American hegemony differs from other empires. 

In the book Liberal Leviathan, written by G. John Ikenberry, the main argument implies that American supremacy was rooted in multilateral institutions that constrained the hegemon itself. NATO’s decision-making process, integrated command and consultation mechanisms limited unilateral American decisions, resulting in what Ikenberry defines “constitutional order”: a situation only durable because of institutional lock-in (Ikenberry, 2011). This difference is crucial. 

Since hegemony becomes institutionalized, its decline doesn’t automatically dissolve international order and, therefore, assessing if Europe is becoming “Post-American” requires evaluating institutional transformation and not merely rhetorical changes or burden-sharing issues. 

Robert Keohane and Joseph Nye’s Theory of Complex Interdependence deepens this logic, stating that in dense institutional environments the costs of sudden rupture are extremely high. Mechanisms such as security cooperation, intelligence sharing agreements and defence networks are deeply institutionalized and, once the hegemon falls, they become technically and politically difficult to dissolve. This logically brings subordinate actors to choose institutional adaptation over structural abandonment (Keohane & Nye, 2001). From this point of view, we obtain three analytical implications.

First, hegemonic decline in the Atlantic system doesn’t automatically produce balancing. It would be true if we followed a classical realist logic assuming low institutional density and high state autonomy, which doesn’t apply to the saturated framework currently present. 

Secondly, dependency on allies isn’t purely coercive. Since reliance depends on decades of coordinated action, dependency has become an operational as much as a political question. 

Finally, an institutionalized hegemony produces an asymmetrical but reciprocal dependency. The U.S. relies on Europe for a number of resources such as intelligence networks, operational bases, logistical corridors and political legitimacy, making a unilateral retreat extremely complicated. 

III. Strategic autonomy 

Keeping in mind the three theories cited above, we can affirm that a genuine “Post-American Europe” requires a structural transformation deeply rooted in the concept of strategic autonomy; an episodic American cutback or simple political friction are not enough. At its core, strategic autonomy refers to an actor’s ability to pursue security and foreign policy goals independent from external forces (Guerrieri & Padoan, 2024). 

At the European Union (EU) level, strategic autonomy refers to collective action within the Union without external interference in multiple areas. In particular, Security and Defence are crucial to Europe, which aims to maintain the ability to deploy forces, prevent conflicts and manage crises independently of NATO or American military assets (Howorth, 2014). This concern is reflected in initiatives such as Permanent Structured Cooperation (PESCO) and the European Defence Fund (EDF), designed to pool resources and build capacities.

Analytically, European strategic autonomy can be operationalized in three main dimensions: independent military capability, institutional command structures, and policy divergence from American preference. This means Europe should aim to being able to replicate U.S. military functions, to supersede or replace NATO’s command centrality in defence structures, and to systematically depart from American grand strategy. These dimensions make autonomy measurable, which is critical to understanding if Europe is genuinely moving towards a “Post-American Era”. 

In practice, the EU’s pursuit of strategic autonomy has increasingly shifted towards different dimensions, reflecting a contemporary evolution of the concept. As of today, the main European aspiration for strategic autonomy is focused on the economic aspect with the concept of OSA, first introduced by the European Commission (EC) in 2021 in the Trade Policy Strategy (European Commission, 2023). The project focuses on issues such as supply chain security and technological sovereignty, key topics emerged after a concerning series of events: Trump’s protectionist policies, the rise of China in the international market, the Covid-19 crisis and energy shocks caused by the invasion of Ukraine. The core idea is to use trade agreements to diversify risks and strengthen the EU’s position, but the lack of central control makes coordination difficult to manage, resulting in a mere future aspiration (Open Strategic Autonomy: Illusion or Reality? ISPI, 2024). 

IV. Methodology and Methods

To answer whether or not Europe is able to transition towards strategic autonomy, this paper uses an analytical qualitative strategy, focusing on mechanisms and causal processes. The study is guided by the theories outlined in Sections II and III, integrating institutional approaches and contemporary concepts of strategic autonomy. 

The perception of an American cutback is the independent variable, as its changes create both incentives and constraints for European actors. The relationship is mediated by three factors: the threatening international environment, the degree of cohesion within the Union, and the European defence and industrial capacity (which determines the ability to translate plans into concrete capabilities). The dependent variable is the degree of European strategic autonomy, measured through the three dimensions explained in Section III: independent military, institutional command structures, and policy divergence from the U.S.

To operationalize these variables, the paper uses a qualitative content analysis examining key documents: the EU Strategic Compass (2022) and NATO Strategic Concepts (2010 and 2022) (The Strategic Compass of the European Union) (NATO 2022 Strategic Concept, 2022) (NATO 2010 Strategic Concept, 2025). These sources provide insight into the main objectives, institutional mechanisms and European alignment with American policies. 

To complement this, the tracing process of European initiatives helps us assess the design, implementation and effectiveness of strategic measures. Major documents include the PESCO, the European Defence Fund (EDF), and the Coordinated Annual Review on Defence (CARD) (PESCO, Member States Driven)  (European Commission, 2025) (Coordinated Annual Review on Defence, 2017). 

While this approach allows an in-depth analysis, it is still limited by the availability of public documents and possibly underrepresents internal deliberations or classified programs. Moreover, the short observation period may lack the evaluation of a long-term evolution. Nonetheless, the methodology provides a robust framework for evaluating whether or not Europe is currently shifting towards an actual “Post-American Era”. 

V. Results

The analysis reveals Europe’s progress is gradual, often specific to distinct areas, and limited by structural and institutional factors. Considering the three levels of autonomy cited previously, the findings demonstrate different levels of development. 

I. Independent military

European States have significantly increased investment in defence and military development, as demonstrated by the PESCO projects and the EDF (European Commission, 2025). However, the gap between European and U.S. military remains significant, especially in areas such as nuclear deterrence and intelligence-sharing. This indicates that military capability in the Union is still partially independent rather than fully operational. 

II. Institutional command structures

EU mechanisms provide limited independence from NATO, particularly for smaller-scale missions. Surely some structures provide a certain degree of freedom in decision-making, but NATO remains the principal framework for European defence operations. The Union’s initiatives are often complementary, not substitutive, and reflect political caution and technical dependency on U.S. assets and coordination. 

III. Policy divergence from the United States

In foreign policies, European positions largely align with major U.S. key points. The principal examples include the sanction regime and the relationship with Russia since the war in Ukraine (an event that increased the transatlantic alignment rather than a strategic divergence). In some areas, such as policies towards China and international trade, the EU is more flexible, but the OSA project remains aspirational (Open Strategic Autonomy: Illusion or Reality? ISPI, 2024). 

Overall, the results suggest the European Union’s strategic autonomy is growing in rhetoric and institutional frameworks, especially in trade and technological advancement, while remaining constrained in the areas of military capabilities and policy divergence. Member States are aware and building towards an era of possible American cutback, yet the Atlantic system survives and shapes operational capacities as much as strategic and political behavior. These findings support the argument of the EU moving towards a managed autonomy within a postwar institutional order characterized by adaptation, rather than towards a true “Post-American Era”.  

VI. Discussion

The empirical findings can be discussed through the lens of the theories presented in Section II: the Hegemonic Stability Theory, the Liberal Leviathan as explained by Ikenberry and the Theory of Complex Interindependence. Viewed together, these three theories can help better assess the European adaptation to a new institutional order. 

The Hegemonic Stability Theory predicts that, when a hegemon steps down, subordinate actors will either compete for leadership or pursue balancing strategies to compensate for the lack of fundamental public goods in the system: security and economic stability (Webb & Krasner, 1989). Logically, this means that perceived American cutback should speed up the process of European defence independence, particularly after the shift of U.S. interests towards the Indo-Pacific area. The empirical results, however, only partially support this idea. It is true that EU Member States have increased defence and activated new instruments such as PESCO and EDF, but they have yet to replace NATO’s structural centrality. Instead, the Atlantic system has been reinforced after the invasion of Ukraine where U.S. forward-deployment has legitimized NATO once again as the primary security framework. 

From a Hegemonic Stability Theory perspective, this suggests that American decline remains relative rather than absolute, at least from a European point of view. The hegemon keeps providing public goods to the system with nuclear deterrence, command structure and intelligence and military capabilities and, as long as the goods remain credible and operational, other actors have little to no incentive to balance the lack of a fully committed hegemon. The result is mainly burden-sharing adjustments, not structural change, which brings Europe to respond with an incremental preparation to a new system rather than substitution. The Atlantic system hasn’t entered a post-hegemonic vacuum, it simply expects a recalibration under continued American rule, even if less committed, thus complicating deterministic theories of hegemonic decline. 

If the Hegemonic Stability Theory is not enough to fully explain the persistence of the Atlantic system dependence, Ikenberry’s Liberal Leviathan provides deeper insight. According to this framework, American postwar hegemony was institutionalized in ways that constrained both the hegemon and other allies (through multilateral agreements and NATO rooting the American supremacy in the international system). The findings confirm this theory and highlight European autonomy initiatives to have developed within, and not against, existing institutional structures. Even if Europe expands trade with OSA and other initiatives, it is always done without dismantling the central role of NATO. This illustrates the institutional lock-in established after 1945; decades of interoperability, shared doctrines and joint operational experience naturally create high exit costs for European States. The EU isn’t merely aligned with the U.S., it has been embedded in a shared architecture for security. The durability of the Atlantic system therefore reflects a deep institutional dependency rather than simple asymmetry. Moreover, the reciprocal nature of the system reflects its resilience: since the U.S. strongly relies on European bases, logistics and political legitimacy to project power, the dependence makes sudden disengagement costly on both sides. The findings therefore support Ikenberry’s theory of an institutionalized hegemony being more durable than a traditional empire due to its ability to endure change and evolve without collapsing. 

Finally, Keohane and Nye’s Theory of Complex Interdependence helps clarify why European strategic autonomy has emerged mainly in specific dimensions without producing a systemic rupture. In an environment with dense institutional ties, economic integration and several channels of interaction, the cost of sudden disengagement is prohibitively high. The EU’s OSA project reflects precisely this logic and tries to manage vulnerability with interdependence by diversifying supply chains and trade, strengthening technological advancement and preventing external shocks. This approach clearly recognizes that interdependence can’t be reversed and that resilience must be built in the already existing system. The findings demonstrate how the Union is advancing strategic autonomy projects in economic and industrial domains, where diversification is technically feasible; while in the areas of military and defence the EU remains resistant to rapid change due to the strong asymmetries in the system. The uneven development strongly aligns with the Theory of Complex Interdependence, demonstrating how dimensions with low security sensitivity and high policy flexibility allow experimentation. Importantly, the theory also suggests that autonomy and interdependence are not mutually exclusive, translating Europe’s pursuit of strategic autonomy not as a systemic abandonment of the Atlantic framework, but as an attempt to reduce vulnerability while preserving institutional ties. 

VII. Conclusion

In conclusion, this article examined whether Europe is undergoing a structural transition towards a “Post-American” order or if it is instead adapting within a change by enduring in the Atlantic framework. By linking empirical observations to the already existing theories of Hegemonic Stability, Complex Interdependence and Ikenberry’s Liberal Leviathan, the analysis provides an assessment of continuity and change in the transatlantic relationship. The central conclusion is firm: Europe is evolving strategically but it has yet to cross the threshold into structural autonomy away from the U.S.. 

From the perspective of Hegemonic Stability, the findings indicate that American decline from the EU’s perspective remains relative due to the continuity in supplying goods. This has been enhanced by the war in Ukraine that deeply contributed to NATO’s operational centrality and demonstrated Europe’s reliance on the U.S. Although European spending has increased in defence and military, these measures supplement the American leadership without substituting it and the dynamic predicted by classical hegemonic decline has therefore not materialized fully. 

The postwar Atlantic order was not designed as a purely hierarchical system, but as a densely institutionalized security community where NATO’s mechanisms have generated path dependency and raised the costs of strategic abandonment. European autonomy has emerged within this architecture confirming the durability of Ikenberry’s constitutional order: American power remains embedded in existing institutions that structure expectations and constrain unilateral decisions. The resilience of the transatlantic relationship therefore reflects institutional entrenchment as much as material capability. 

Simultaneously, the analysis identifies significant shifts in European strategy, particularly regarding economic and industrial domains; the rise of OSA is proof of an expanded understanding of vulnerability in a new era of geopolitical competition and rivalry. Europe’s efforts to diversify economic dependence and strengthen industrial coordination illustrate a strategy of resilience-building within interdependence. In line with Keohane and Nye’s theory, these developments don’t aspire to disengagement but to recalibration within the system where autonomy and interdependence coexist. In summary, Europe seeks to reduce asymmetry and vulnerability while preserving institutional benefits of the transatlantic relationship. 

The broader implication is that strategic autonomy should be viewed as incremental and multidimensional since Europe is neither passively dependent nor fully independent; it is in an intermediate position characterized by managed autonomy and institutional continuity. Military autonomy remains constrained, while economic resilience initiatives demonstrate flexibility, leaving Europe to pursue an uneven trajectory shaped by external threats, internal cohesion and credibility of American commitments. 

Looking forward, the durability of this equilibrium will depend on structural and political variables where a sustained U.S. cutback, combined with deeper EU defence, could accelerate a stronger shift. On the other hand, persistent security threats and ongoing institutional interdependence are likely to reinforce Atlantic ties. For now, the evidence supports the conclusion of Europe not being “Post-American” but in the process of adapting to a new world order. Strategic autonomy has emerged not as a rupture, but as a resilience strategy designed to prevent uncertainty while preserving the foundations of transatlantic security. 

VIII. References

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European Commission. (2025). European Defence Fund (EDF) https://defence-industry-space.ec.europa.eu/eu-defence-industry/european-defence-fund-edf-official-webpage-european-commission_en

European Commission . Making trade policy.  (2023). https://policy.trade.ec.europa.eu/eu-trade-relationships-country-and-region/making-trade-policy_en

Guerrieri, P., & Padoan, P. (2024). “European competitiveness and strategic autonomy” The European Union and the double challenge: strengthening competitiveness and enhancing economic security https://leap.luiss.it/wp-content/uploads/2024/03/WP5.24-European-competitiveness-and-strategic-autonomy-.pdf

Howorth, J. (2014). Security and defence policy in the European Union. Palgrave Macmillan. https://doi.org/10.1111/j.1468-5965.2007.00764_9.x

Ikenberry, G. J. (2011). Liberal Leviathan. Princeton University Press. https://doi.org/10.1002/j.1538-165X.2012.tb02277.x

Keohane, R. O., & Nye, J. S. (2001). Power and Interdependence. Longman Publishing Group. https://doi.org/10.1080/00396337308441409

NATO 2010 Strategic Concept. (2025). https://www.nato.int/en/about-us/official-texts-and-resources/strategic-concepts/strategic-concept-2010

NATO 2022 Strategic Concept. (2022). https://www.nato.int/en/about-us/official-texts-and-resources/strategic-concepts/nato-2022-strategic-concept
Open strategic autonomy: illusion or reality? ISPI. (2024, June 6). https://www.ispionline.it/en/publication/open-strategic-autonomy-illusion-or-reality-175757

PESCO | Member States Driven. Permanent Structured Cooperation (PESCO). https://www.pesco.europa.eu/

The Strategic Compass of the European Union. https://www.strategic-compass-european-union.com

Webb, M. C., & Krasner, S. D. (1989). Hegemonic stability theory: an empirical assessment. Review of International Studies, Volume 15 (Special issue 2), 183–198. https://doi.org/10.1017/S0260210500112999

Artificial intelligence was used solely for brainstorming and discussing the general structure of this article; all research, analysis and writing were conducted by the author.