CIA director David Petraeus was surprised when he read the freshly rewritten talking points an aide had emailed him in the early afternoon of Saturday, September 15. One day earlier, analysts with the CIA’s Office of Terrorism Analysis had drafted a set of unclassified talking points policymakers could use to discuss the attacks in Benghazi, Libya. But this new version​—​produced with input from senior Obama administration policymakers​—​was a shadow of the original. The original CIA talking points had been blunt: The assault on U.S. facilities in Benghazi was a terrorist attack conducted by a large group of Islamic extremists, including...