offers the first comprehensive assessment of the geopolitical implications of "global aging"-the dramatic transformation in population age structures and growth rates being brought about by falling fertility and rising longevity worldwide. It describes how demographic trends in the developed world will constrain the ability of the United States and its traditional allies to maintain national and global security in the decades ahead. It also explains how dramatic demographic change in the developing world-from resurgent youth bulges in the Islamic world to premature aging in China and population implosion in Russia-will give rise to serious new security threats. While some argue that global aging is pushing the world toward greater peace and prosperity, warns that a period of great geopolitical danger looms just over the horizon. Neither the triumph of multilateralism nor democratic capitalism is assured. The demographic trends of the twenty-first century will challenge the geopolitical assumptions of both the left and the right.