Talks to revive the Iran nuclear deal resumed in Vienna amid renewed tensions as Tehran prepares to ramp up uranium enrichment following an alleged sabotage attack on the country's main nuclear site.
Iran and other parties to the 2015 agreement -- Britain, France, Germany, China, and Russia -- last week launched what has been described as 'constructive' talks to bring Washington and Tehran into full compliance with the accord.
But on April 13, Iran announced it would start enriching uranium at up to 60 percent purity, higher than it has ever done before, casting a shadow on the negotiations at which European countries have worked as intermediaries between Washington and Tehran.
Iranian officials say the move comes in reaction to an alleged attack on the Natanz nuclear site two days earlier that they have blamed on archenemy Israel.
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U.S. Secretary of State Antony Blinken said Tehran's 'provocative' announcement on enrichment 'calls into question Iran's seriousness with regard the nuclear talks.'
Britain, France, and Germany expressed 'grave concern' over Tehran's 'dangerous' announcement, saying it was 'contrary to the constructive spirit and good faith' of ongoing efforts to revive the 2015 pact.
Under the deal, abandoned by the United States under former President Donald Trump, Iran had committed to keep enrichment to 3.67 percent. Recently it has been enriching up to 20 percent, saying the deal was no longer enforceable.
While enriching uranium to 60 percent would be the highest level achieved by Iran's nuclear program, it is still short of the 90 percent purity needed for military use. Tehran has repeatedly denied it is seeking nuclear weapons and that its nuclear ambitions are purely for civilian purposes.
Few details have emerged about the April 11 alleged sabotage attack, which Iranian officials said knocked out power at the enrichment plant in central Iran.
Israel has neither confirmed nor denied involvement but multiple Israeli media outlets quoted unnamed intelligence sources as saying that the country's Mossad spy service carried out a successful sabotage operation at the Natanz site.
Lawmaker Alireza Zakani, who heads the research center of Iran's hard-line parliament, said in an interview that 'several thousand centrifuges were damaged and destroyed.' Other officials said that only first-generation machines had been affected.
Citing two intelligence sources, The New York Times has reported that production at Natanz could be set back by at least nine months due to the attack.
Inspectors from the International Atomic Energy Agency (IAEA), the UN nuclear watchdog, have visited the site but have not commented on the extent of the damage caused by the alleged attack.
However, the IAEA did say that Iran had 'almost completed preparations' to enrich uranium to 60 percent purity.
The 2015 nuclear deal lifted international sanctions on Tehran in exchange for limits on its nuclear program. But the Trump administration imposed a raft of sanctions under a 'maximum pressure' campaign after it withdrew from the nuclear agreement in 2018.
Iran responded by gradually breaching many of the nuclear restrictions, saying the deal no longer applied.
U.S. and Iranian officials have publicly clashed over the sequencing of possible U.S. sanctions relief and Iran reversing its breaches of the deal.
Iranian Foreign Minister Mohammad Javad Zarif on April 15 said the Natanz attack had unleashed a 'dangerous spiral' and warned Biden the situation could only be contained by lifting the sanctions Trump imposed.
'No alternative. Not much time,' he wrote on Twitter.
Addressing a cabinet meeting, Iranian President Hassan Rohani reiterated that his country is 'not seeking to obtain the atomic bomb.'
'If others return to full compliance with the deal...we will stop 60 percent and 20 percent enrichment,' he said.
Ali Vaez, director of the Iran project at the International Crisis Group think tank, said that events of the past few days had 'added urgency' to the talks.
'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,' he added.
Eric Brewer, a senior fellow at the Center for Strategic and International Studies, told RFE/RL that 'enriching to 60 percent is a significant Iranian step and will further shorten Iran's breakout timeline.'
However, the Iranian move was 'unlikely to have the intended effect of forcing the U.S. to accept Iran's demands,' said Brewer, who served as a deputy national intelligence officer and was responsible for monitoring Iran's nuclear program.
With reporting by AFP, Reuters, dpa, and RFE/RL's Radio Farda
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