Iran began enriching uranium Friday to its highest-ever purity, edging close to weapons-grade levels, as it attempts to pressure negotiators in Vienna during talks on restoring its nuclear deal with world powers after an attack on its main enrichment site.

A top official said only a few grams an hour of uranium gas would be enriched up to 60% purity — triple its previous level but at a quantity far lower than what the Islamic Republic had been able to produce. Iran also is enriching at an above-ground facility at its Natanz nuclear site already visited by international inspectors, not deep within underground halls hardened to withstand airstrikes.

The narrow scope of the new enrichment provides Iran with a way to quickly de-escalate if it chooses, experts say, but time is narrowing. An Iranian presidential election looms on the horizon as Tehran already threatens to limit international inspections. Israel, suspected of carrying out Sunday’s sabotage at Natanz, also could act again amid a long-running shadow war between the two Middle East rivals.

Mohammad Bagher Qalibaf, Iran’s parliament speaker, announced the higher enrichment on Twitter.

“The young and God-believing Iranian scientists managed to achieve a 60% enriched uranium product,” Qalibaf said. “I congratulate the brave nation of Islamic Iran on this success. The Iranian nation’s willpower is miraculous and can defuse any conspiracy.”

The head of the Atomic Energy Organization of Iran, the country’s civilian nuclear arm, later acknowledged the move to 60%. Ali Akbar Salehi told Iranian state television the centrifuges now produce 9 grams an hour, but that would drop to 5 grams an hour in the coming days.

“Any enrichment level that we desire is in our reach at the moment and we can do it at any time we want,” Salehi said.

It wasn’t clear why the first announcement came from Qalibaf, a hard-line former leader in the paramilitary Revolutionary Guard already named as a potential presidential candidate in Iran’s upcoming June election.

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While 60% is higher than any level Iran previously enriched uranium, it is still lower than weapons-grade levels of 90%. Iran had been enriching up to 20% — and even that was a short technical step to weapons-grade. The deal limited Iran’s enrichment to 3.67%.

The International Atomic Energy Agency, which monitors Iran’s nuclear program, did not respond to a request for comment. Earlier this week, it sent its inspectors to Natanz and confirmed Iran was preparing to begin 60% enrichment at an above-ground facility at the site.

Israel, which has twice bombed Mideast countries to stop their nuclear programs, plans to hold a meeting of its top security officials Sunday over the Iranian announcement.

“Israel is determined to defend itself against any attempt to harm its sovereignty or citizens, and will do whatever it takes to prevent this radical and anti-Semitic regime from acquiring nuclear weapons,” Israeli Foreign Minister Gabi Ashkenazi said in Cyprus.

Iran insists its nuclear program is peaceful, though the West and the IAEA say Tehran had an organized military nuclear program up until the end of 2003. An annual U.S. intelligence report released Tuesday maintained the longtime American assessment that Iran isn’t currently trying to build a nuclear bomb.

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Iran previously had said it could use uranium enriched up to 60% for nuclear-powered ships. However, the Islamic Republic currently has no such ships in its navy.

The threat of higher enrichment by Iran already had drawn criticism from the U.S. and three European nations in the deal — France, Germany and the United Kingdom. On Friday, European Union spokesman Peter Stano called Iran’s decision “a very worrisome development.”

“There is no credible explanation or civilian justification for such an action on the side of Iran,” Stano said. The Vienna talks aim to “make sure that we go back from such steps that bring Iran further away from delivering on its commitments and obligations.”

Diplomats reconvened Friday in Vienna, with more talks planned Saturday, Russian representative Mikhail Ulyanov said. Chinese negotiator Wang Qun earlier called for doing “away with all disruptive factors by moving forward as swiftly as we can on the work of negotiations, especially by zeroing in on sanction lifting.”

The 2015 nuclear deal, which former President Donald Trump unilaterally withdrew the U.S. from in 2018, prevented Iran from stockpiling enough high-enriched uranium to be able to pursue a nuclear weapon if it chose in exchange for the lifting of economic sanctions.

In Washington, President Joe Biden said Tehran’s latest step was contrary to the deal. “We do not support and do not think it’s at all helpful,” he said. But he added that the Vienna talks had not been sidetracked.

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“We are nonetheless pleased that Iran has agreed to continue to engage in indirect discussions with us on how we move forward and what is needed to get back” into the nuclear deal, he said. “It’s premature to make a judgment as to what the outcome will be, but we’re still talking.”

The weekend attack at Natanz was initially described only as a blackout in its electrical grid — but later Iranian officials began calling it an attack.

One Iranian official referred to “several thousand centrifuges damaged and destroyed” in a state TV interview. However, no other official has offered that figure and no images of the aftermath have been released.

In the coming weeks, Iran has threatened to further impede IAEA inspections and potentially destroy video recordings it now holds of its facilities. Meanwhile, it continues to use advanced centrifuges and gain know-how in high enrichment, something that worries nonproliferation experts.

“Because the deal has started to unravel, Iran has begun to acquire more knowledge about how to operate more advanced machines,” said Daryl G. Kimball, the executive director of the Washington-based Arms Control Association. “This particular operation, enriching to 60%, is going to give it even more information.”

Borrowing a term used to describe diluting high-enriched uranium, Kimball added: “That knowledge cannot be down-blended. It cannot be reversed.”