To the amazement of the public, pundits, and even the policymakers themselves, the ideological and political conflict that had endangered the world for half a century came to an end in 1990. How did that happen? What caused the cold war in the first place, and why did it last as long as it did? The distinguished historian Melvyn P. Leffler homes in on four crucial episodes when American and Soviet leaders considered modulating, avoiding, or ending...