Aug. 13 (UPI) -- Britain, Germany and France told U.N. officials that snapback sanctions are on the table if Iran does not sit down to negotiate over its nuclear weaponry. The letter delivered to United Nations Secretary-General Antonio Guterres , signed by the three foreign ministers, indicated the E3 was prepared to enforce severe sanctions if Iran did not agree to limit it's nuclear program and gave Iranian officials until the end of the month. "We have made it clear that if Iran is not