From grassroots terrorism to the nuclear ambitions of hostile nations, the United States faces increasingly complex threats to its national security. Combating these threats continues to demand a reshaping of the nation's security structure, military forces and defense expenditures. In this study, Anthony Cordesman offers a detailed analysis of critical challenges affecting U.S. national security and how failures in adapting to these challenges have exacerbated the strains on available resources. He systematically identifies the most glaring obstacles to successful national security...