From “Can You Tell a Sunni From a Shiite?” in The New York Times:

At the end of a long interview, I asked Willie Hulon, chief of the [FBI�s] new national security branch, whether he thought that it was important for a man in his position to know the difference between Sunnis and Shiites. �Yes, sure, it�s right to know the difference,� he said. �It�s important to know who your targets are.�That was a big advance over 2005. So next I asked him if he could tell me the difference. He was flummoxed. �The basics goes back to their beliefs and who they were following,� he said. �And the conflicts between the Sunnis and the Shia and the difference between who they were following.�O.K., I asked, trying to help, what about today? Which one is Iran � Sunni or Shiite? He thought for a second. �Iran and Hezbollah,� I prompted. �Which are they?�He took a stab: �Sunni.�Wrong.