	Introduction

Since the mid-1980s, many decision makers and others have demonstrated serious interest in deploying ballistic missile defense (BMD) systems capable of defending the United States from ballistic missile attack. In fact, efforts to counter ballistic missiles have been underway since the dawn of the missile age at the close of World War II. Since 1985, the United States has spent more than $120 billion on a range of BMD efforts. This short report provides a brief overview of the history of the BMD efforts undertaken to defend the United States. It begins with a brief summary of the provisions of the 1972 ABM Treaty, which shaped most of the history of the U.S. BMD effort, and includes a short review of U.S. programs leading to the current program. Throughout this period, Congress tendered strong support for the ABM Treaty. National Missile Defense Acquisition

President George W. Bush entered office prepared to advance long-range BMD deployment as a key national security objective. Russian opposition has been strong, and European support is mixed.
For some time now, ballistic missile defense (BMD) has been a key national security priority, even though such interest has been ongoing since the end of World War II. Many current BMD technologies date their start to the 1980s, and even earlier. This effort has been challenging technically and politically controversial. For a 25-year review of the major BMD technology thrust, see CRS Report RL33240, Kinetic Energy Kill for Ballistic Missile Defense: A Status Overview , by [author name scrubbed].
More than $120 billion has been spent on a range of BMD programs since the mid-1980s; Congress appropriated $9.4 billion for FY2007 and $9.9 billion for FY2008. This report provides a brief overview of U.S. BMD efforts to date. It may be updated periodically.