The United States has pursued missile defences since the dawn of the missile age shortly after World War II. The development and deployment of missile defences has not only been elusive, but has proven to be one of the most divisive issues of the past generation. The Bush Administration substantially altered the debate over missile defences. The Administration requested significant funding increases for missile defence programs (about 61% above that approved by Congress for FY2001), eliminated the distinction between national and theatre missile defence, restructured the missile defence program to focus more directly on developing deployment options for a 'layered' capability to intercept missiles aimed at US territory across the whole spectrum of their flight path, adopted a new, untried development and acquisition strategy, announced US withdrawal from the 1972 Anti-ballistic Missile Treaty, and is planning to deploy an initial missile defence capability by 2004-2005. The Bush Administration's plans raise a number of issues, many of which are examined in this book. The issues that will continue to receive attention are 1) ballistic missile proliferation; 2) a new acquisition concept for developing missile defence that does not lend itself readily to oversight, system definition, or cost and effectiveness analysis; and, 3) the deployment of a mid-course missile defence system in Alaska and California.