Ballistic missile defense (BMD) has been a key national security priority for some time, even though such interest has been ongoing since the end of World War II. As part of its effort to develop a global ballistic missile defense (BMD) system, the Department of Defense (DOD) has modified three Navy cruisers and 15 Navy destroyers for BMD operations, and has deployed a large BMD radar on a modified floating oil platform. This book provides a brief overview of the history of the BMD efforts undertaken to defend the United States and begins with a summary of the provisions of the 1972 ABM Treaty, which shaped most of the history of the U.S. BMD effort, and includes a review of U.S. programs leading to the current program. This book consists of public documents which have been located, gathered, combined, reformatted, and enhanced with a subject index, selectively edited and bound to provide easy access.