UNTIL THE EARLY morning of June 17, when French SWAT teams went over the walls, the riverside compound on this quiet street served as a political headquarters for the most famous (and infamous) group trying to overthrow the government of Iran: the Mojahedin e-Khalq (People’s Mojahedin), which is listed by the United States and the European Union as a terrorist organization. For years the outfit was a pawn of Saddam Hussein. But now the Muj, who are some of the Iranian ayatollahs’ oldest enemies, may be America’s new friends and thus, perhaps, France’s new enemies. The Rajavis fled to exile...