Beyond the Battlefield: US Foreign Policy and European Security Transformation in the Shadow of the Ukraine War

The paper examines the evolving trajectory of United States foreign policy towards Russia, Ukraine, and the broader European security architecture, with particular emphasis on the strategic shifts between the Biden and Trump administrations. It argues that the inconsistency and discontinuity characterising American policy towards Russia over successive administrations created permissive conditions for Vladimir Putin's neo-imperial agenda, ultimately contributing to his decision to launch a full-scale invasion of Ukraine in February 2022. The analysis identifies four defining features of Trump's foreign policy approach—individualism, unpredictability, transactionalism, and the absence of coherent grand strategy—and traces their implications for transatlantic relations and European security. The paper contends that the 2025 National Security Strategy represents a critical inflection point, fundamentally reframing Europe's role within American strategic calculations. While nominally reaffirming alliance commitments, the NSS effectively repositions Europe from strategic partner to subordinate implementer, expected to assume primary responsibility for regional defence whilst Washington prioritises other theatres. This strategic repositioning reflects what the paper terms a shift from a "shared threat–shared strategy" model towards a "sequenced burden-sharing" framework. Crucially, the NSS downplays Russia as a long-term strategic threat in favour of diplomatic stabilisation—a stance that stands in sharp contrast to European strategic documents, including the EU Strategic Compass, which continue to identify Russia as an enduring, primary challenge requiring sustained deterrence. Drawing on alliance theories, particularly on such issues as patron-client dynamics and abandonment-entrapment dilemmas, combined with role theory, the paper analyses how American discursive devaluation of Europe as a strategic actor is reshaping transatlantic hierarchical order dynamics. European responses emerge as partially contradictory: rhetorically reinforcing transatlantic unity whilst simultaneously advancing strategic autonomy initiatives and hedging against American unpredictability—exemplified by the ReArm Europe plan and emerging frameworks for post-war security guarantees for Ukraine. The paper traces emerging fault lines in EU-US relations crystallising around three dimensions: divergent Russia threat assessments, contested burden distribution within the alliance, and tensions over democratic governance norms. Process-tracing of diplomatic interactions following key policy pronouncements reveals patterns of convergence and divergence across these areas. Theoretically, the paper refines strategic autonomy debates by demonstrating that European autonomy imperatives are now driven not solely by retrenchment fears but by explicit American strategic devaluation of Europe—a qualitatively different dynamic with profound implications for the future of Western security cooperation. The analysis contributes to understanding how major power strategic recalibrations generate reactive adaptations in alliance structures during an era of intensified great power competition and contested liberal international order.