Iran talks: How close is a final nuclear deal?
This week in Vienna the real business begins.
So far the nuclear talks between Iran and the five permanent members of the UN Security Council along with Germany - the so-called P5+1 - have been, as one insider put it, "about clearing the ground".
On 13 May, talks start in earnest to try to draft an actual agreement that will provide a comprehensive solution to the Iranian nuclear issue.
The ambitious goal is to get this done before the end of July. This is when the six-month interim agreement expires.
Three months of intensive discussions lie ahead.
If the clock runs out and things are going well, then an extension is of course possible.
But alternatively, if a deal is not in sight, then the negotiating track may have run its course and the consequences could ultimately be very serious indeed.
'So far, so good'
Experts and diplomats are unanimous in their view that so far the negotiations have gone surprisingly well.
As nuclear expert Mark Hibbs of the Carnegie Endowment for International Peace notes: "The very fact of the absence of unauthorised leaks to the press about difficulties encountered in the negotiation, and the control that the negotiators have exerted on what we know via gatekeepers, are positive signs that there is political will on both sides to see this through to the end."
Mark Fitzpatrick, the director of the Non-Proliferation and Disarmament Programme at the International Institute for Strategic Studies (IISS) in London, puts it this way: "So-far, so good. The interim agreement is being honoured and talks on a comprehensive deal are exuding good vibes.
"All parties," he adds, "are behaving responsibly."
Mr Hibbs notes that from the outset "because a big challenge was mutual lack of trust, the road map for this negotiation began with confidence-building measures aimed at picking low-hanging fruit.
"They're picking it, but the hardest part may be the last, and there are some potential show-stoppers ahead," he says, with emphasis.
"Negotiators," Mr Hibbs adds, "still have to deal with the legacy of Iran's clandestine activities which the International Atomic Energy Agency (IAEA) believes was related to a nuclear weapons option.
"They will have to agree on how much of a nuclear programme Iran can have at the end of the day and for how long it will be circumscribed, and how sanctions-lifting will be matched with remaining steps by Iran."
All or nothing
It is also crucial to understand the nature of any deal that might emerge.
Whatever nuclear work or research Iran may have conducted in the past, it cannot simple "unlearn" any knowledge it may have acquired.
Thus, it is not going to be possible to arrive at a deal where it can be said for certain that Iran will never be able to develop a nuclear weapon.
So for the major UN players, a successful deal will be one where robust answers can be provided to two key questions:
- Can the international community detect with a very high level of certainty any effort by Iran to seek a nuclear weapon in the future?
- And crucially, how far away would Iran then be from having a nuclear device? Bluntly, how long would it take for Iran to obtain a nuclear weapon?
Everything depends upon a sufficient degree of transparency in Iran's nuclear programme and a sufficient degree of warning before Iran "gets the bomb".
Diplomats close to the talks say that there are areas where the two sides are closer than might be expected and others where they are a long way apart.
But a 95% agreement will not be enough. As one analyst put it: "You cannot bolt the front door and leave a window at the back of the building ajar".
Despite the doubts many had only a year ago, Western diplomats believe that a deal is indeed possible. But they insist that if there is to be agreement then there has to be a lot of movement on the part of the Iranians.
The details to be resolved at the negotiating table are horrendously complicated.
As Mr Hibbs notes: "The talks have got to the point where Iran is ready to include in its nuclear narrative history to the IAEA aspects which have so far not been explained.
"They're on the path to account for Iran's uranium procurement activities; they're dealing with the issue of electronic bridge wires [nuclear detonators] research and development; and if Iran is to be believed then Tehran is prepared to convert the IR-40 Arak reactor away from plutonium production."
The Iranians say the reactor is intended to produce electricity, but its spent fuel could be reprocessed to yield plutonium, potentially giving Iran an alternative route to the bomb.
"What's yet to come is the bulk of incriminating allegations concerning nuclear weapons-related research - how many centrifuges Iran can have at the end; whether Iran can continue to do R&D on far more advanced centrifuge and laser enrichment technology; and whether Iran will agree to an even more robust verification regime than any other non-nuclear weapons state has formally agreed to accept," said Mr Hibbs.
Mr Fitzpatrick believes that because of the complexity of the remaining issues the talks will continue beyond July.
"I see no narrowing of differences on the size of the enrichment programme, the disposition of excess centrifuges, and the duration of limits, to name three," he says.
"It remains very unlikely that the parties will be able to resolve these deeply contentious issues by 20 July. More likely, they will extend the current six-month deal."
But Mr Fitzpatrick says that it is still too early to talk about an extension.
"The focus of the negotiators is rightly on the goal of a comprehensive deal," he notes. "For them to discuss extension of the interim measures would be a forecast of failure. But at some point they will have to."
Even an extension of the talks could raise difficult issues.
Would Iran request further sanctions relief as the price for remaining at the table, and how long could talks continue without success before they became pointless?
Nonetheless, many analysts believe that any future extension of the talks should probably be seen as a positive step; an indication that progress is being made and that the final goal is still in sight.