This volume examines the evolution of US foreign policy since Donald Trump's accession to the presidency and the strategic challenges confronting the United States in a changing geopolitical environment. Trump has delivered on his promises to break with past policies and this has, for the most part, revealed a policy of retrenchment that has jeopardized US alliances. The book focuses on the current state and future of transatlantic relations, on Washington's policy in the Middle East and Africa, on the administration's use of the economic weapon in international relations, but also on the American response to the return of great power competition in the face of an assertive China and resurgent Russia. The contributions gather the inputs of a transatlantic community of scholars combining academics, think-tank fellows, former policy-makers and administration officials from both sides of the Atlantic.