But a last-ditch diplomatic blitz in Vienna in recent days involving Kerry and the other foreign ministers failed to bridge the remaining gaps.
This included eight meetings since Tuesday between Kerry and Zarif and numerous other gatherings in the Austrian capital.
– Gaps on crucial points –
Diplomats said that, despite some progress, both sides remain far apart on two crucial points: uranium enrichment and sanctions relief.
Enriching uranium renders it suitable for peaceful purposes like nuclear power. But at high purities it is also used as the fissile core of a nuclear weapon.
Tehran wants to massively ramp up the number of enrichment centrifuges in order, it says, to make fuel for a fleet of power reactors that it is yet to build.
The West wants the enrichment dramatically reduced, a move which together with more stringent UN inspections and an export of Iran’s uranium stocks, would make any attempt to make the bomb all but impossible.
Iran wants painful UN and Western sanctions that have strangled its vital oil exports lifted, but the powers want to stagger any relief over a long period to ensure Tehran complies with any deal.
– More time on the clock –
The conditions set by last November’s interim deal will remain in place until July, including a continued freeze by Iran of contentious parts of its nuclear activities.
In return, Iran will keep receiving around $700 million (560 million euros) in frozen funds per month, British Foreign Secretary Philip Hammond said, or $4.9 billion by July, adding to some $7 billion received since January.
Another extension — as happened to an earlier deadline of July 20 — however carries risks of its own, including possible fresh US sanctions that could lead Iran to walk away.
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