As negotiations over Iran’s nuclear program resume in Geneva this week, observers and policymakers are sharply divided on the role of economic sanctions. Those who want to give negotiations a chance, including U.S. President Barack Obama and Secretary of State John Kerry, believe that the United States and its allies should be willing to ease sanctions in exchange for Iranian cooperation. Those who remain suspicious of Iran’s intentions, including many in Congress, maintain that the United States should double down on sanctions to force Iran to comply with its demands.
History suggests that once imposed, the promise to lift sanctions often offers more leverage than efforts to keep them from leaking. To be sure, there is no question that the sting of economic sanctions contributed to Iranian President Hassan Rouhani’s recent charm offensive. But sanctions were hardly the sole reason he came to the table: The window for negotiations opened only after Mahmoud Ahmadinejad, a president who Iran’s supreme leader, Ayatollah Ali Khamenei, no longer trusted, was replaced by someone he does -- at least for now. Domestic politics in Iran and the United States will determine whether that window stays open or slams shut once more. To keep it open, Rouhani will have to show his audience at home that he can win some relief. And in the United States, Congress will have to allow Obama sufficient flexibility to use sanctions as the bargaining chip they are.
Throughout history, sanctions have rarely caused countries to capitulate outright. Colleagues from the Peterson Institute for International Economics and I analyzed 204 instances of sanctions in the twentieth century (all the cases we could identify). We found that they achieved part of their goals about a third of the time. Indeed, most of the successful examples involved compromise and partial accomplishments. Only in 12 cases did sanctions lead directly to their intended results.
Overall, we concluded, sanctions were most likely to be effective when the sanctioner’s goals