Book excerpt: A “second nuclear age” has begun in the post-Cold War world. Created by the expansion of nuclear arsenals and new proliferation in Asia, it has changed the familiar nuclear geometry of the Cold War. Increasing potency of nuclear arsenals in China, India, and Pakistan, the nuclear breakout in North Korea, and the potential for more states to cross the nuclear-weapons threshold from Iran to Japan suggest that the second nuclear age of many competing nuclear powers has the potential to be even less stable than the first. Strategy in the Second Nuclear Age assembles a group of distinguished scholars to grapple with the matter of how the United States, its allies, and its friends must size up the strategies, doctrines, and force structures currently taking shape if they are to design responses that reinforce deterrence amid vastly more complex strategic circumstances. By focusing sharply on strategy—that is, on how states use doomsday weaponry for political gain—the book distinguishes itself from familiar net assessments emphasizing quantifiable factors like hardware, technical characteristics, and manpower. While the emphasis varies from chapter to chapter, contributors pay special heed to the logistical, technological, and social dimensions of strategy alongside the specifics of force structure and operations. They never lose sight of the human factor—the pivotal factor in diplomacy, strategy, and war.