Talk about missed deadlines. In Vienna an historic deal on Iran's nuclear programme was supposed to be signed by today. Exit the French foreign minister, Laurent Fabius, who says he won't return to town until late on Wednesday. He listed the main eleventh-hour sticking points: curbing Iran's ability to develop its nuclear program, the pace at which sanctions are lightened, and the UN watchdog's access to military sites. Is failure an option in these negotiations that started 12 years ago?