When and how did these talks begin?

Talks that led to a breakthrough interim agreement agreed in November of 2013, known both as the Geneva Accord and the Joint Plan of Action, began in February of that year. Prior to that there had been numerous (unsuccessful) attempts to negotiate a deal with Iran since 2002 when Iranian dissident groups raised the alarm over the country’s nuclear programme by revealing the existence of two facilities that had not been declared to the International Atomic Energy Agency (IAEA), the UN’s nuclear watchdog. Two things have given the current talks real momentum, however. The first was a back channel to Iran opened up by the Obama administration in March 2013 that led to several secret bilateral meetings in Oman. The second was the election in June of 2013 of Hassan Rohani, who 10 years before had served as Iran’s nuclear negotiator, on a platform promising constructive engagement with the international community aimed at lifting harsh economic sanctions and ending Iran's international isolation. The negotiations leading to Thursday’s pact kicked off in March 2014. Several deadlines for a comprehensive agreement were extended. The final deadline has now been set for July 1st of this year, but the White House needed a detailed framework agreement to be in place well before the return of Congress from its Easter break, in order to head off an attempt by Republican critics of any deal with Iran to legislate for new sanctions and thus kill off the talks.

Who are the P5+1? Why not call it the P6?

The P5+1 are America, France, Britain, China, Russia and Germany. The first five are all permanent members of the UN Security Council. Germany is there because it was part of an EU3 including France and Britain, that held an earlier series of negotiations with Iran. The European Union is also represented at the talks by its foreign affairs supremo. The UN Security Council has passed a series of resolutions imposing sanctions on Iran since 2006 following reports by the IAEA regarding Iran's non-compliance with its safeguards agreement under the Nuclear Non-Proliferation Treaty (NPT). Sanctions were first imposed when Iran rejected the Security Council’s demand that Iran suspend all uranium enrichment-related and reprocessing activities.

What did they hope to get out of a deal?

In short, the P5+1 wants to prevent Iran from getting a nuclear weapon, or at least to stop it from being able to get one either very quickly or clandestinely. To that end the negotiators have compromised over allowing Iran to continue to enrich uranium, concluding that complete dismantling of a huge infrastructure was unrealistic. However, they have sought strict limits on Iran’s enrichment programme, the redesign of a plutonium-producing heavy water reactor under construction and a highly-intrusive inspection regime to prevent cheating. Their aim has been to extend Iran’s “breakout capability”—the key yardstick of the time needed to produce enough fissile material for one nuclear weapon—from the current estimate of a couple of months to at least a year, and to maintain it there for a decade or more.

What did Iran hope to receive?

For Iran, the pressing need is to gain relief from sanctions that have ratcheted up in severity and are having a crippling effect on its resource-dependent economy. In particular, restrictions on its oil and gas exports, its ability to import technology to exploit its energy resources, and being cut off from SWIFT, the financial-messaging system used to transfer money between the world’s banks, have taken an increasing toll. Iran would have liked all sanctions to end from the moment of a deal being signed, but relief will be staged on the basis of good faith implementation of whatever limits on the nuclear programme are finally agreed. Sanctions related to other aspects of Iran’s behaviour, such as human-rights issues, support of terrorism and its ballistic-missile programme will not be affected. Furthermore, Mr Obama can only suspend sanctions that Congress has legislated.

What does the deal actually include?

The agreement announced on Thursday night was more detailed than most expected, but nothing is in place until a formal deal is signed before the July 1st deadline. However, under this statement of intent Iran will reduce its installed enrichment centrifuges from 19,000 to 6,000, only 5,000 of which will be spinning. All of them will be first-generation centrifuges: none of its more advanced models can be used for at least 10 years, and R&D into more efficient designs will have to be based on a plan submitted to the IAEA. Fordow, Iran’s second enrichment facility (its main one is at Natanz) which is buried deep within a mountain and thought to be impregnable to conventional air strikes, will cease all enrichment and be turned into a physics research centre. It will not produce or house any fissile material for at least 15 years. Iran has said it will reduce its stockpile of low-enriched uranium (which can be spun further into weapons-grade material) from 10,000kg to 300kg for the next 15 years. Iran’s alternative plutonium path to a bomb also appears to have been satisfactorily dealt with. The heavy-water reactor at Arak will be redesigned and its original core, which would have produced significant quantities of weapons-grade plutonium, will be removed and destroyed. No other heavy-water reactor will be built for 15 years.

An interactive guide to the Middle East's tangled conflicts All these undertakings hinge on the assurance that Iran will abide by them. Without a uniquely intrusive inspection and verification regime, sceptics would still be right to question their worth given Iran’s past history of lying and cheating over its nuclear programme. Under the terms of the framework agreement, inspectors from the IAEA will be able to inspect any facility, declared or otherwise, as long as it is deemed to be “suspicious”. The agreement also states that Iran will address the IAEA’s concerns about what it calls the Possible Military Dimensions (PMDs) of its nuclear programme. Such powers for the IAEA, which will remain in place indefinitely, are a lot more sweeping than those it has under the normal safeguard agreements that are part of the Nuclear Non-Proliferation Treaty. What needs to happen by July 1st?

Basically, a lot more of the technical detail needs to be filled in. The exact nature of the inspection and verification regime is especially important as are the penalties for non-compliance (such as automatic snapback of US and EU sanctions and new UN resolutions). Because the framework agreement was so specific, some of the heavy lifting has been done. But the negotiator’s watchword is that until everything is agreed, nothing is agreed. Who is hoping the deal falls apart? What are the odds they get their wish?

The deal has many strenuous critics. The Israeli prime minister, Binyamin Netanyahu, has described it in almost apocalyptic terms (although much of Israel’s security establishment is more sanguine about it); Republican hawks in Congress (and even some Democrats) hate the idea of any deal with Iran that does nothing to address its behaviour as a troublemaker in the Middle East and as a sponsor of designated terrorist outfits, such as Hizbullah in Lebanon. The deal is also opposed by hardliners in Tehran who may still be hoping to win over the enigmatic but ailing supreme leader, Ali Khamenei, to their point of view. Elements of the powerful Iranian Revolutionary Guard (IRG), who control military sites which the IAEA will have to gain access to if it is to address the vital PMD issues, may be quite happy to find a way of sabotaging the deal. The IRG may even wish to see sanctions remain in place, as they have provided money-making opportunities for many of its leaders. However, the problem faced by those who would like to see the deal collapse is that they have yet to offer any attractive alternatives. Ordinary Iranians are desperate to get back to having a normal economy, while American voters have little appetite for going to war with Iran to prevent it getting a nuclear weapon. According to a Washington Post-ABC News poll conducted just before the agreement on April 2nd was announced, Americans support the notion of striking a deal with Iran that restricts the nation’s nuclear program in exchange for loosening sanctions, by a nearly two to one margin.

If the deal holds together, what does that mean for the Middle East?

That is hard to say. Overall, if the deal does what it is meant to, it should make the region a bit safer, heading off, at least for now, the prospect of a dangerous nuclear arms race involving Saudi Arabia and perhaps Egypt and Turkey as well. Israel will surely be more secure if Iran’s breakout capability is extended to over a year from just a month or so and its whole nuclear programme becomes vastly more transparent. What a deal is most unlikely to do, at least in the short-term, is to make Iran a more cooperative, less aggrandising player in the region’s geopolitics. If Iran feels richer, there is a risk it may actually interfere more. This is an arms-control deal between adversaries, not a friendship hug. Interests will continue to diverge between Iran and the West. Just possibly, however, if Iran’s economy becomes re-integrated with the world, and a degree of trust is established on all sides by Iran's meeting the obligations they have signed up to, something more fruitful could eventually emerge.

Dig deeper:

The deal with Iran is better than the alternatives (April 2015)

How the deal with Iran will play in America (April 2015)

How the deal looks in Iran (April 2015)