Donald Trump's ascendancy has seemingly transformed the US's relationships with both its allies and adversaries. How much, however, has been bluster and how far have realities changed? Has Trump ushered in, as he has so often claimed, a new era? This book looks back at Trump's first term of office and brings a new perspective to the debate. It considers Trump's impact on US foreign policy through the analytical lens of policy feedback and, on this basis, assesses the opportunities that were open to him and the constraints that reined in his administration, particularly in its dealings with Russia, Europe, the Middle East and East Asia. The book argues that Trump not only took strategic advantage of the opportunities open to him but changed policy in ways that bound his successor and set the stage for his second administration. Trump has, in other words, presided over changes in the trajectory of US foreign policy that, in certain arenas at least, has been genuinely transformative.