This issue brief, authored by Richard Nephew, Program Director for Economic Statecraft, Sanctions and Energy Markets at the Center on Global Energy Policy, examines the possible application of new sanctions against Iran if a deal is not achievable between Iran and the P5+1. Nephew concludes that new sanctions would be a far riskier strategy to pursue than a successful negotiation and outlines the best way to design a sanctions regime if, unfortunately, it is needed. The brief reviews the logic of sanctions and how they can be best calibrated to achieve desired effects, drawing on lessons from past sanctions experience. Nephew is a former director for Iran at the U.S. National Security Council and was a member of the U.S. nuclear negotiating team with Iran from August 2013 to December 2014. The views expressed here are his own.