This book develops an updated classification of US foreign policy approaches and explores the evolving role of presidential leadership in shaping the United States’ strategy amid growing global uncertainty. Focusing on Presidents Barack Obama, Donald Trump, and Joe Biden, it demonstrates how the personality traits, along with the educational and professional backgrounds of US presidents, mold their leadership styles and influence America’s international conduct. The study underscores the complex interplay between presidential personalities and structural constraints in the formation of US foreign policy, highlighting a broader trajectory of America’s declining global influence, exacerbated by inconsistent foreign policies and a retreat from her traditional leadership role. The book examines the implications of Washington’s vacillating policies in the post-unipolar world. It warns that America’s credibility and leadership are at risk unless her future administrations adopt a more resolute and coherent strategy to counter challenges and threats to international peace and security.