For almost three quarters of a century, the United States has spent billions of dollars and countless person-hours in the pursuit of a national missile defense system that would protect the country from intercontinental ballistic missiles (ICBM) carrying nuclear warheads. The system currently in place consists of 44 long-range antiballistic missiles stationed in Alaska and California to protect the United States from a possible nuclear weapon carrying ICBM attack from North Korea. After all this effort, this systemis still imperfect, being successful only 10 out of 18 tests. This book will provide an historical description of past efforts in national missile defenses to understand the technical difficulties involved. It will also explain how national security concerns, the evolving international environment, and the complexities of US politics have all affected the story. The book will also describe the current systems in place to protect allies and troops in the field from the threat of shorter range missiles. Finally, the book will describe the current US vision for the future of missile defenses and provide some suggestions for alternative paths.