Probably more than at any point in its history, the United States enjoys a commanding, and growing, military advantage over other states in the international system. The troubling and counterintuitive result is that such undisputed superiority is not making the United States safer. Rather, it is spurring an underground network of trade in unconventional technology and weapons that is both increasing American vulnerability to catastrophic acts of WMD terrorism and potentially decreasing the credibility of US commitments to resolve regional crises and conflicts in its favor.

Part I introduced this dilemma, with chapter 1 observing that there is a crisis of confidence regarding the durability of deterrence. It examined reasons why the United States may be unwilling to adopt a purely reactive posture in international affairs, including the stability–instability paradox and the possibility of states providing terrorists with sanctuary or WMD. Chapter 2 then applied a theoretical lens to the puzzle, explaining how asymmetries of interest and brinksmanship techniques can confer a strategic advantage beyond what one would expect from a pure comparison of military capability. It explained that estimations of resolve are directly linked to subjective variables such as risk-sensitivity and degree of commitment, each based on psychological factors that may not be strictly rational. Thus, even were the United States fully committed to a particular course of action, deterrence may not function as it expects, particularly in last resort situations or when dealing with millenarian regimes.