Constraining Iran's Future Nuclear Capabilities

March 28, 2019

Weapon Program: 

  • Nuclear


Robert Einhorn and Richard Nephew


The Brookings Institution


The United States needs a new strategy for effectively constraining Iran’s future nuclear capabilities. The Trump administration’s current approach has little chance of succeeding. But simply returning the United States to the Joint Comprehensive Plan of Action (JCPOA) is not a long-term solution. By the time the United States would return to the 2015 deal, key nuclear restrictions would soon expire. Moreover, achieving the wide domestic support needed to make a nuclear deal with Iran politically sustainable in the United States would not be served by simply turning the clock back to before Trump took office. 

The United States needs to pursue a renewed nuclear bargain with Iran, building on the solid foundation of the original and addressing its shortcomings. Diplomacy must play a central role in that effort, which will require: 

  • Mending fences with the Europeans and other key negotiating partners to rebuild the broad international support needed to press Iran to come to the negotiating table and accept meaningful restraints;
  •  Abandoning the current administration’s excessive demands in favor of a more realistic negotiating position that keeps Iran a safe and verifiable distance from the nuclear weapons threshold for an extended period of time, while demonstrating to Iran a willingness to accept an outcome compatible with Tehran’s legitimate interests;
  • Pursuing a new deal focused on the nuclear issue, while actively and effectively—although separately and in parallel—implementing a broad strategy for addressing the other dimensions of the Iranian challenge, including its aggressive regional activities and its missile program; 
  • Improving the incentives (primarily sanctions relief) that would be offered to Iran, both in terms of their scope and their reliability to deliver anticipated benefits, in order to persuade Iran to accept a renewed bargain that goes beyond the JCPOA in important respects, especially in terms of the duration of its nuclear restrictions; and
  • Making every effort to gain wide domestic support in the United States for any new negotiated outcome in order to make it durable and politically sustainable, despite presidential leadership transitions in Washington. 

While diplomacy should take center stage in efforts to constrain Iran’s future nuclear capabilities, diplomacy alone is not enough. The Trump administration’s anti-Iran campaign has put great pressure on Tehran, but it has also reinforced Iranian opposition to U.S. demands and resistance to even engaging with the United States. To promote productive  negotiations—and in the event that negotiations fail—diplomacy will have to be complemented by other policy tools that do not require Iran’s participation or consent, such as  sanctions, counterproliferation measures, and deterrence. These more coercive policy tools can impede and discourage Iran’s movement toward the nuclear weapons threshold and provide incentives for Iran to negotiate seriously. But in the end, nuclear restraint must be Iran’s choice and is best codified in a renewed nuclear agreement.