Diplomats said Thursday that the latest talks in Vienna to save the 2015 Iran nuclear deal were positive despite fresh tensions over Tehran's announcement that it was preparing to ramp up uranium enrichment in response to an attack on a facility it blamed on arch-foe Israel.
The latest round of diplomatic negotiations aimed at ensuring the US's return to the accord lasted for roughly two hours on Thursday afternoon, with Russia's ambassador to the UN in Vienna, Mikhail Ulyanov, tweeting afterwards that the "general impression is positive".
The talks comprised delegations from the remaining parties to the deal following the US exit -- Germany, France, Britain, China, Russia and Iran.
There had been fears that developments in recent days could cast a pall over the talks, with a European diplomat telling AFP ahead of the meeting that Iran's announcement that it would enrich uranium up to 60 percent "puts pressure on everyone".
The move would take Iran closer to the 90 percent purity level needed for use in a nuclear weapon.
Tehran says the enrichment move is a response to Israel's "nuclear terrorism" after an explosion on Sunday knocked out power at its Natanz enrichment plant.
Israel has neither confirmed nor denied involvement, but public radio reports in the country said it was a sabotage operation by the Mossad spy agency, citing unnamed intelligence sources.
- 'Ready to advance' -
Despite the latest developments on the ground, the chair of the talks, EU diplomat Enrique Mora, also struck an upbeat note at the end of Thursday's meeting.
He tweeted that participants had been "ready to advance... despite very challenging events and announcements over the past days".
Another diplomatic source said there had been "no big problems" at the talks, which is now expected to be followed by fresh meetings of experts to discuss possible measures to be taken by Washington and Tehran on sanctions lifting and nuclear issues.
The head of the Iranian delegation, Abbas Araghchi, was more cautious at the end of Thursday’s meeting.
According to a statement from Iran's foreign ministry, Araghchi stressed that Tehran wanted to avoid the talks "dragging on" and that they had to "take place in a well-defined framework and within an acceptable time period".
He also stated that the planned rise in enrichment levels was in order to "meet some of the country's medical needs".
Brussels has rejected this argument, with EU external affairs spokesperson Peter Stano saying there was "no credible or plausible civilian justification" for the move.
US Secretary of State Antony Blinken said late Wednesday that the announcement on uranium "calls into question Iran's seriousness with regard to the nuclear talks".
His Iranian counterpart Mohammad Javad Zarif retorted on Twitter that "Iran's 'seriousness of purpose' in pursuing diplomacy was tested in the three years since Trump withdrew from the nuclear accord".
"Iran -- by remaining in the deal -- passed with flying colors," he said, accusing US President Joe Biden of continuing the "maximum pressure" policy towards Iran followed by his predecessor Donald Trump.
Trump dramatically withdrew from the deal -- known as the Joint Comprehensive Plan of Action (JCPOA) -- in 2018 and went on to re-impose sanctions against Iran, prompting Tehran to retaliate by exceeding the accord's limits on its nuclear activity.
- 'Humiliating attack ' -
The events of the past few days have "reminded both parties that the status quo is a lose-lose situation", and have "added urgency" to the Vienna talks, said Ali Vaez, Iran Project Director at the International Crisis Group think tank.
"It is clear that the more the diplomatic process drags on, the higher the risk that it gets derailed by saboteurs and those acting in bad faith," Vaez added.
In the meantime, the European diplomat said that Tehran is reducing its "breakout time" -- the time needed to acquire the fissile material necessary for the manufacture of a bomb.
Under the JCPOA, Iran had committed to keep enrichment limited to 3.67 percent, though it stepped this up to 20 percent in January.
The UN's International Atomic Energy Agency said its inspectors visited the site at Natanz for "verification and monitoring activities" on Wednesday, and that Iran had "almost completed preparations" to enrich uranium to 60 percent purity.
"It was unrealistic to expect Iran not to respond to such a humiliating attack at the heart of its nuclear programme," the ICG's Vaez said.
"But the only thing that in the past two decades has effectively curtailed Iran's nuclear programme has been diplomacy, not sanctions or sabotage."