Experts helping to negotiate the Iran nuclear talks have reached a tentative agreement on how and when to lift U.S. and European Union sanctions against Iran — but the nations' foreign ministers must still accept the deal, NBC News has learned. While officials say they have narrowed the gaps on all issues, some sticking points remain ahead of Tuesday's deadline. One of the toughest sanctions issues still unresolved: How the separate United Nations sanctions would be "snapped back on" if Iran were found to have violated any part of the final agreement with the world powers. The U.S., along with Britain, China, France, Germany and Russia, are seeking to work out a deal to keep Iran from developing nuclear weapons. In exchange, economic sanctions levied against Iran — and in place for decades — would be lifted.
