The Iran deal may be the most significant agreement on Middle Eastern affairs since the Oslo Accords of 1993. It could prove the signature achievement of Iran's President Hassan Rouhani and the defining foreign policy legacy of U.S. President Barack Obama. It is not a perfect deal for the West as it does not roll back Iran's nuclear program nor end all its enrichment. It is not the best possible deal for Iran because sanctions will be phased out only gradually over five to eight years and can be restored rapidly if the agreements are violated; and because the International Atomic Energy Agency (IAEA) will have more intrusive access than to any other country that has not been defeated in war.
But it is a good deal because it is acceptable to all parties — the essence of diplomatic negotiations. The Joint Comprehensive Plan of Action will be translated into a new U.N. Security Council resolution that will replace and supersede six earlier sanctions resolutions imposed on Iran over its nuclear program.
The P5+1 (China, France, Russia, United Kingdom, United States, plus Germany) were guided by three sets of considerations: to deter, dissuade and delay nuclear weaponization by Iran; to detect any efforts at nuclear breakout by Iran; and if Iran is caught cheating, to have sufficient time to coax and/or coerce it back into the non-nuclear box. That has been achieved through a reasonably regime involving robust transparency, inspections and consequences.