How has it happened that the United States and the Soviet Union have managed to get through more than four decades of Cold War confrontation without going to war with one another? Historian John Lewis Gaddis suggests answer to this and other vital questions about post-war diplomacy in this new book. Gaddis uses recently declassified American and British documents to explore several key issues in Cold War history that remain unresolved: Precisely what itwas about the Soviet Union's behaviour after World War II that American leaders found so threatening? Whether the United States really wanted a sphere of influence in post-war Europe? What led the Truman administration first to endorse, but then immediately to avoid American military involvement on the mainland of Asia? This is a provocative exercise in contemporary history, certain to generate new insights on both past and present aspects of the age we live in.