This is the second of two draft volumes on the history of strategic air and ballistic missile defense from 1945 to 1972. It covers the 1955-1972 portion of the larger period, and is organized into five interrelated and progressively more detailed chapters. Chapter I provides a comparison of U.S. and Soviet strategies, Chapters II and III deal with U.S. strategy and Soviet strategy, while Chapters IV and V cover U.S. systems and Soviet systems.