Book excerpt: As the 21st century approaches, the international community continues to grapple with the consequences of major shifts in the security environment. The world we now live in is a paradox: political integration and community fragmentation; expanding transnationalism and rising nationalism; unimaginable wealth and unspeakable poverty, high-tech militarizes and low-tech conflicts, decreasing military spending and expanding use of defense resources. In this complex environment, the United States is debating its global role and security priorities for the 21st century.