<p>This paper analyzes the impact of Donald Trump’s first administration’s NATO strategy on transatlantic relations, with a particular focus on his transactional approach to alliance management. While previous analyses have explored the broader implications of Trump’s foreign policy, this study offers a novel contribution by examining the ways in which his NATO strategy reshaped the power dynamics within the alliance and influenced European responses to American demands. Drawing on realist theory and liberal institutionalism, the paper investigates how Trump’s emphasis on bilateralism, burden-sharing, and the threat of US withdrawal disrupted NATO’s traditional multilateral framework. By analyzing key NATO documents, official statements, and policy shifts from both the US and European states, this study highlights the tension between power politics and institutional norms within NATO, demonstrating how Trump’s actions prompted long-term strategic recalibrations in European defense initiatives. The article argues that, while Trump’s policies strained transatlantic cooperation, they also catalyzed European efforts toward greater defense autonomy, with potential implications for NATO’s future cohesion. This study contributes to ongoing debates in NATO studies and US foreign policy by offering new insights into the evolving nature of transatlantic security relations in the post-Cold War era.</p>