But so far, it seems there are a few remaining sticking points that are proving fairly difficult to resolve. The main issue of contention between the Iranian and Western camps is an ongoing investigation by the International Atomic Energy Agency — the U.N.’s nuclear watchdog — into unexplained traces of uranium found at Iranian facilities in the early 2000s. Tehran wants the investigation closed before they’ll accept any deal; the IAEA and U.S. and European governments are so far refusing.