Kerry Says Working into the Night on 'Tricky' Iran Nuclear Issues

U.S. Secretary of State John Kerry said Monday he and his global counterparts were going to work deep into the night seeking to resolve the remaining "tricky issues" as a deadline loomed within hours.

"There still remain some difficult issues," Kerry told a CNN reporter as he walked in his luxury lakeside hotel in the Swiss town of Lausanne. 

"We are working very hard to work those through. We are working late into the night and obviously into tomorrow."

A deadline for the framework of a deal expires at midnight on Tuesday and officials appealed to all parties to make a huge final effort.

"We've been negotiating since September of 2013," said acting State Department spokeswoman Marie Harf, referring to the first meeting between Kerry and Iranian Foreign Minister Mohammad Javad Zarif "and it's sort of time to see whether they can make these decisions."

With all eyes focused on Tuesday's deadline, Harf said she could not predict what would happen if the outlines of a deal were not agreed in time.

"We have no idea what will happen if we can't get this done by the 31st. Obviously we always are planning for contingencies," she told reporters on a conference call.

"We will have to take a very hard look at where we are and we will have to decide what happens next, and I don't want to predict what that outcome will be."

"We just don't know where we're going to be at this time tomorrow, and we will really have to see tactically and strategically what makes the most sense going forward. I think we will know a lot more this time tomorrow."

But Harf stressed "there's still a path to do this" adding there was still a 50-50 chance of a deal.

Adding to the drama, Russian Foreign Minister Sergei Lavrov left the crunch talks in Switzerland after a series of meetings, Russian media reported.

He will only return if there is a "realistic" chance of a deal, his spokeswoman said earlier.

Lavrov and his counterparts from the United States, China, Britain, France and Germany met with the Iranians in the Lausanne hotel on Monday for their first full session since missing a previous November deadline.

A Western diplomat said it was "yes or no" time, adding that the talks remained blocked on three major issues -- the length of the accord, the lifting of U.N. sanctions and a mechanism to ensure both sides stick to the deal.

Global powers have set a midnight Tuesday deadline to agree the outlines of a deal that they will then try to finalize by June 30. Only then would Iran receive sanctions relief, diplomats said.

- Ample notice -

The global powers want Iran to scale back its nuclear program to give the world ample notice of any dash to make the bomb and end a crisis that has threatened to escalate dangerously for 12 years.

The diplomatically-isolated Islamic republic denies wanting atomic weapons and is calling for the lifting of sanctions that have strangled its lifeblood oil exports and its access to the global financial system.

The threat of new U.S. sanctions, and domestic pressure on Iranian President Hassan Rouhani for his attempts at rapprochement with the West, all but rule out any further extension of the deadline.

"We had a very important meeting, and detailed discussions," Iran's lead negotiator Abbas Araghchi said, while insisting "we have solutions" for most of the remaining issues.

Even before a deal is sewn up, opponents have railed against it, fearing it will not do enough to stop Iran getting the bomb.

These include U.S. President Barack Obama's Republican opponents and Israel, widely believed to be the sole, if undeclared, nuclear-armed power in the Middle East.

Saudi Arabia -- leading an Arab coalition which on Monday carried out a fifth straight night of air strikes on Iran-backed rebels in Yemen -- is also uneasy about any thawing in U.S.-Iran ties.

Israeli Prime Minister Benjamin Netanyahu, in his second broadside in two days, said Monday a deal would be tantamount to Tehran being "rewarded" for its "aggression" in Yemen.

- Jigsaw puzzle -

Western diplomats say some areas in a highly complex jigsaw puzzle are tentatively agreed. But they caution there is a long way to go.

One said Sunday that Iran had "more or less" agreed to slash the number of its centrifuge enrichment machines from 20,000 to 6,000 and to ship abroad most of its stockpile of low-enriched uranium.

This would make it a much more lengthy process to further purify these stocks to weapons-grade.

Iranian officials dismissed the numbers as "speculation", with Araghchi ruling out sending the stocks abroad, although he said "other options" were being examined.

This could include diluting low-enriched uranium or converting it to another form.

In addition to scaling down its nuclear program, the powers want Iran's remaining facilities to be subject to an unprecedented level of inspections by the U.N. atomic watchdog.

Its underground facility at Fordo would also likely be barred from uranium enrichment, diplomats said, although it might be kept open for research purposes.

The United States, EU and others are only prepared to suspend their sanctions, not terminate them, and in a phased manner in order to ensure that Iran does not violate the deal.

The issue of U.N. Security Council sanctions is particularly tricky.

Araghchi said Sunday there must be a "precise framework" for lifting sanctions. The duration of any deal -- the United States wants at least 10 and possibly up to 15 years -- is also a point of contention.

With the world's fourth biggest oil and second biggest gas reserves, the energy industry is the cornerstone of Iran's economy, but it was hit hard by the American and European embargo imposed in 2012.

The sanctions sent the economy of the OPEC member state into recession but it is now reporting growth again.