While defense planners have recently proposed a variety of alternatives for America's role in what many see as a New World Coming, few of those proposals go beyond the Cold War paradigm of threat-based strategic thinking. This paradigm focuses on deterring or defeating specific threats, rather than taking advantage of the intrinsic dynamism of the new security environment in order to create conditions that might promote long-term peace, stability, and prosperity. America's challenge today is to foster peace and stability in a dynamic world and to do so with strategic partners and allies willing and able to share the costs just as surely as they reap the benefits. Hence, instead of a strategy oriented on prevention-a negative aim-the United States would do better to lead a 21st-century concert of nations toward creating positive conditions, those that promote long-term peace, stability, and prosperity. Such a strategy would, as a matter of course, preclude a number of threats-perhaps even the majority of them from emerging in the first place and would better position the United States to cope with unexpected emergencies. New Global Challenges and Opportunities. The forces of globalization are creating something of a Janus-faced future for the international community. At one extreme, the future takes on the countenance of a stable world in which national interests merge into the general aim of promoting peace, stability, and economic prosperity. At the other extreme, the future assumes the face of a more dangerous and unpredictable world characterized by shifting power relationships, ad hoc security arrangements, and an ever-widening gap between haves and have-nots. The face of the future that comes into view will undoubtedly have features representing both extremes. The extent to which the United States and other powers work in concert will make a difference in determining which aspect of Janus will become more prevalent. The United States can address the challenges of the new security environment through any one of three broad strategic approaches: preventive defense, neo-isolationism, or a strategy aimed at positive ends. Preventive Defense. Preventive Defense aims at forestalling potential problems by deterring, containing, isolating, and defeating specific threats. Its success depends on developing the correct list of threats; and it generally seeks to preserve or restore the status quo. It provides for deterring and defeating, if necessary-such potential aggressors as Saddam Hussein in Iraq and Kim Jong Il in North Korea. However, a strategy of preventive defense, even if successful in deterring or defeating designated threats, could fail if other threats emerge that military forces are neither equipped nor trained to confront. It also falls short of providing a rationale for taking control of events that might shape the future or of building a broad multinational basis for anticipating and addressing the type of problems commonly associated with today's strategic environment.