ABSTRACT
This chapter examines the evolving partnership between NATO and the European Union, highlighting the interplay between cooperation, competition, and structural inertia. Since the end of the Cold War, NATO–EU relations have undergone multiple phases shaped by geopolitical shifts, the development of the European Security and Defence Policy, crises such as the wars in Ukraine, and the transformative impact of US administrations, particularly Donald Trump's first and second presidencies. Despite shared security objectives, the partnership has often produced limited practical outcomes due to institutional asymmetries, overlapping memberships, diverging strategic cultures, and political cleavages among member states. The chapter traces key milestones in NATO–EU cooperation, from early post-Cold War arrangements and the Berlin Plus framework to enhanced collaboration following Russia's 2014 and 2022 aggressions in Ukraine, including joint task forces and coordinated defence initiatives. It then deals with the impact of the two Trump presidencies (as of April 2025) on Transatlantic relations and on NATO–EU relations. The analysis underscores that while informal and technical cooperation has advanced, comprehensive strategic alignment remains constrained by political disagreements, capability gaps, and differing threat perceptions. The chapter concludes by arguing that the current transatlantic and intra-European dynamics make it increasingly urgent to envision an innovative European security architecture that reconciles autonomy, capability development, and operational coherence in the face of enduring challenges to the liberal world order.
