This book examines the interplay between political culture and diplomatic strategy in the U.S., revealing the transformation of American political culture and its impact on the country’s foreign strategy. The theoretical pivot of this study is an analysis of the dynamics of political culture and the mechanisms of the interaction between political culture and diplomatic strategy. Given this premise, the core chapters revisit the historical transformations of American political culture and analyze the responses and countermeasures taken to attempt to reverse the perceived decline in American hegemony during the presidencies of George W. Bush, Barack Obama, and Donald Trump, factors interwoven with security, economic, and institutional crises. The discussion describes the landscape and evolution of contemporary American political culture and the correlated adjustments of U.S. global strategy over the course of the twenty-first century. Given the myriad of challenges and political legacies left by its predecessors, the author gives a pessimistic prognosis of the prospect of resolving America’s political plight by the Joe Biden administration. The title will be a valuable reference for academic and general readers interested in American politics, U.S. diplomatic strategy, and international relations.