This latest product of Harvard's Avoiding Nuclear War Project takes off from the premise that deterrence is not likely to fail soon but will not last forever. The contributing authors thus examine long-term paths to a more stable world, ranging from the technology of strategic defense or more discriminating weapons to the politics of Soviet decline and improved U.S.-Soviet relations. The analysis is careful, the conclusions thoughtfully modest. Not surprisingly, no path is a panacea: the world could be safer, for example, if the Soviet Union declined gracefully like the British Empire, but could be more dangerous if the decline were akin to that of the Austro-Hungarian Empire. The book's editors put their faith, in the short run, in policies and force postures to "lengthen the fuse" to nuclear weapons and, for the long term, in an evolution of U.S.-Soviet relations.