This document provides a summary of key conclusions from chapters in a book analyzing national security threats to the United States based on President Obama's final National Security Strategy. It finds that the top threats are: 1) state actors like Russia, North Korea, and Iran that pursue nuclear weapons and military aggression; 2) the rising economic and military power of China; and 3) non-state actors like al-Qaeda and ISIS that use social media and cyber capabilities to finance and carry out terrorist attacks across wide geographic areas. It recommends that the US strengthen cyber infrastructure and monitoring, continue military assistance programs, and use diplomatic and economic tools to address these challenges.