Iran has vowed to take "revenge" for an alleged act of sabotage at its main Natanz nuclear site that it blames on its archenemy Israel, an incident that could overshadow diplomatic efforts to revive the 2015 nuclear deal abandoned by former U.S. President Donald Trump.
Ali Akbar Salehi, the head of Iran's Atomic Energy Organization, said an act of "nuclear terrorism" caused a power failure at the Natanz nuclear facility on April 11, a day after new uranium-enrichment equipment was unveiled at the site, south of Tehran.
The underground Natanz site is key to Iran's enrichment program and monitored by inspectors of the International Atomic Energy Agency (IAEA), the UN nuclear watchdog, which said it was aware of the reports of an incident but would not comment.
State TV on April 12 quoted Foreign Minister Mohammad Javad Zarif as putting the blame on Israel for the incident, saying the country wanted to "take revenge because of our progress in the way to lift sanctions."
"They have publicly said that they will not allow this. But we will take our revenge from the Zionists," Zarif added. He did not provide any hard evidence of Israeli involvement in the incident.
The European Union warned against attempts to derail talks to return Washington to the Iran nuclear deal.
Russia's Foreign Ministry said in a statement on April 12 that it was closely following the situation surrounding the "serious incident."
It added that it was "alarming how this situation" could impact the talks to revive the deal, which are set to resume in Vienna on April 14.
The EU-hosted talks center on overcoming an impasse between the United States and Iran to bring both parties into full compliance with the 2015 agreement, known as the Joint Comprehensive Plan of Action (JCPOA), which lifted international sanctions on Tehran in exchange for limits on Iran's nuclear program. The U.S. and Iranian sides have publicly clashed over the sequencing of possible U.S. sanctions relief and Iran reversing its breaches of the deal.
"We hope that what happened will not become a 'gift' to the assorted opponents of the JCPOA and will not undermine the consultations that are gaining momentum...to revive these agreements," the Russian statement said.
Multiple Israeli media outlets have quoted unnamed intelligence sources as saying that the country's Mossad spy service had carried out a successful sabotage operation at the Natanz site, potentially setting back enrichment work there by months.
Israel has not confirmed any role in the incident and generally does not comment on clandestine operations, though Prime Minister Benjamin Netanyahu repeatedly has described Iran as the greatest threat facing his country.
The New York Times, citing American and Israeli intelligence officials, reported Israel had a role in what it described as a "large explosion" at Natanz that destroyed an internal power system that supplies underground centrifuges that enrich uranium.
The intelligence officials said the damage to the power system was enough to knock out Natanz's uranium enrichment for at least nine months.
Israel is suspected of carrying out sabotage against Iran in the past, including cyberattacks and assassinations of nuclear scientists.
Last year, a fire broke out at an aboveground part of the Natanz nuclear facility, which the government said was an attempt to sabotage Iran's nuclear program. In November, Iran's top nuclear scientist, Mohsen Fakhrizadeh, was killed in an attack on his car near Tehran. Iran blamed Israel for the assassination.
Israel has intensified a long-running shadow war against Iran, ranging from upping airstrikes on Iran-aligned forces in Syria to a suspected mine attack earlier this month on a ship used by the Islamic Revolutionary Guards Corps off the coast of Yemen.
The reported blackout at Natanz occurred a day after Iran launched new advanced centrifuges at the Natanz facility with the potential to accelerate uranium enrichment, in another breach of the country's commitments in the 2015 nuclear agreement with world powers.
The incident casts additional uncertainty over the upcoming talks in Vienna to revive the nuclear accord long opposed by Israel.
"What we are hearing currently out of Tehran is not a positive contribution, particularly the development in Natanz," German Foreign Minister Heiko Maas said ahead of the Vienna talks.
EU foreign-policy spokesman Peter Stano said the bloc rejected "any attempts to undermine or weaken diplomatic efforts on the nuclear agreement," and insisted that "we still need to clarify the facts" over events at Natanz.
Zarif said Tehran would not allow the incident to affect the discussions, state news agency IRNA reported.
The EU-hosted talks in Vienna center on overcoming an impasse between the United States and Iran to bring both parties into full compliance with the 2015 agreement, known as the Joint Comprehensive Plan of Action (JCPOA), which lifted international sanctions on Tehran in exchange for limits on Iran's nuclear program.
President Joe Biden has expressed a willingness for the United States to reenter the accord abandoned by the Trump administration, which then imposed a raft of sanctions on Tehran under a "maximum pressure" campaign. Iran responded to the U.S. exit from the deal in 2018 by gradually breaching many of the nuclear restrictions.