The stakes are high. Both Russia and China are increasingly challenging the United States and its allies. Iran is ramping up its nuclear program. North Korea can now hit the United States with nuclear-tipped missiles. Al Qaeda and other terrorist groups may step into the vacuum created by the U.S. departure from Afghanistan. Nations like Libya and Yemen are in chaos. The U.S. military faces the twin challenge of maintaining its combat advantage in the information age while facing looming budget constraints. The National Security and Defense program aims to help policymakers and the public better understand these and other threats facing the United States and the options available for responding to them.