This book reconstructs and explains the arms relationship that successive U.S. administrations developed with the Shah of Iran between 1950 and 1979. This relationship has generally been neglected in the extant literature leading to a series of omissions and distortions in the historical record. By detailing how and why Iran transitioned from a primitive military aid recipient in the 1950s to America's primary military credit customer in the late 1960s and 1970s, this book provides a detailed and original contribution to the understanding of a key Cold War episode in U.S. foreign policy. By drawing on extensive declassified documents from more than 10 archives, the investigation demonstrates not only the importance of the arms relationship but also how it reflected, and contributed to, the wider evolution of U.S.-Iranian relations from a position of Iranian client state dependency to a situation where the U.S. became heavily leveraged to the Shah for protection of the Gulf and beyond - until the policy met its disastrous end in 1979 as an antithetical regime took power in Iran. This book will be of interest to students and scholars of Middle East studies, US Foreign Policy and Security studies and for those seeking better foundations for which to gain an understanding of U.S. foreign policy in the final decade of the Cold War, and beyond.