In a region of troubles, the negotiations over Iran's nuclear program stand out. The first-step agreement, signed in November 2013, broke a decade of futile diplomatic forays punctuated by mutual escalation. The product of a rare confluence of political calendars and actors, it set a framework for a balanced arms-control agreement that could form the basis of a comprehensive nuclear accord. But reasons for caution abound. It is easier to pause than to reverse the escalation pitting centrifuges against sanctions. Mistrust remains deep, time is short, and the process remains vulnerable to pressure from domestic and regional detractors. In bringing the sides together, the accord revealed the chasm that separates them. Success is possible only with political will to isolate the deal – at least for now – from its complex regional context. It will ultimately be sustainable only if the parties, building on its momentum, recognize that their rival's legitimate interests need to be respected. But a far-reaching resolution of differences will be possible only after a relatively narrow, technical nuclear agreement.

This report presents a blueprint for achieving that agreement. It is guided by four objectives: building a firewall between Iran's civilian and potential military nuclear capabilities by constraining the most proliferation-prone aspects of its nuclear program; enhancing transparency by establishing rigorous monitoring and verification mechanisms; ensuring implementation and deterring non-compliance by establishing objective and compulsive monitoring and arbitration mechanisms, as well as by devising, in advance, potential responses to breaches by either party; and bolstering the parties' incentives to remain faithful to the agreement by introducing positive inducements rather than purely negative ones.

A comprehensive agreement based on these principles should be implemented in three phases, the first of which would start with steps that clearly demonstrate the parties' commitment to the process and provide them with immediate tangible benefits, while delaying the heavy lifting until their investment in the process is greater, the costs for withdrawing higher and at least some skeptics have bought into the process.

The detailed recommendations that follow lay out this path in 40 actions. It is a path that carries risks for both sides. There is no guarantee that Iran will remain faithful to its commitments after international attention shifts. Nor is there certainty that the U.S. Congress will accept the deal and provide the president with the necessary authority on sanctions.

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See full text at the International Crisis Group: Iran and the P5+1: Solving the Nuclear Rubik's Cube