A power outage, apparently caused by a deliberately planned explosion, struck Iran’s uranium enrichment facility in Natanz on Sunday in what Iranian officials called an act of sabotage, which they suspected was carried out by Israel.
The blackout added new uncertainty to diplomatic efforts that began last week to save the 2015 nuclear deal, which the Trump administration had rejected.
Iran did not say exactly what caused the blackout at the heavily fortified site that was a target of previous sabotage, and Israel publicly declined to acknowledge or deny any responsibility. But American and Israeli intelligence officials said there was an Israeli role.
Two intelligence officials, briefed on the damage, said it was caused by a large explosion that completely destroyed the independent – and heavily protected – internal power system that powers the underground centrifuges that enrich uranium.
Officials, who spoke of a classified Israeli operation on condition of anonymity, said the explosion severely affected Iran’s ability to enrich uranium and that it could take at least nine months to restore Natanz’s production.
If so, Iran’s leverage in new talks the Biden government is seeking to restore the nuclear deal could be severely affected. Iran has announced that it will take increasingly stringent measures, which are prohibited under the agreement, pending the lifting of the sanctions imposed by President Donald J. Trump.
It was not immediately clear how much, if any, foreword the Biden administration received on the Natanz operation, which took place the same morning that Secretary of Defense Lloyd J. Austin III visited Israel. But Israeli officials have made no secret of their misfortune about Mr Biden’s desire to revive the nuclear deal, which his predecessor renounced in 2018.
Ali Akbar Salehi, the head of the Iranian Atomic Energy Agency, described the blackout as an act of “nuclear terrorism” and said the international community must face the threat.
“This morning’s action against the Natanz Enrichment Agency shows the defeat of those who oppose our country’s nuclear and political development and the substantial gains made by our nuclear industry,” Salehi told the Iranian news media. “The incident shows the failure of those who speak out against Iran and negotiate easing sanctions.”
Israel, viewing Iran as a terrible adversary, has previously sabotaged Iran’s nuclear work with tactics ranging from cyberattacks to outright assassinations. Israel is believed to have orchestrated the killings of several Iranian nuclear scientists in recent years, including an ambush against a key developer of its nuclear program last November.
Israel neither approves nor denies such acts on political grounds.
The explosion in Natanz came barely a week after the United States and Iran, in their first major diplomacy under the Biden administration, participated in the new talks in Vienna aimed at reviving the nuclear deal abandoned by Mr Trump, the it as “the worst deal” and a giveaway for Iran.
Talks to rescue the deal, known as the Joint Comprehensive Plan of Action (JCPOA), are slated to resume this week.
It was not immediately clear how the Natanz incident might affect this. But Iran now faces a complicated calculation of how to react, especially if it concludes that Israel was responsible.
“Tehran faces an extremely difficult equilibrium,” said Henry Rome, Iran analyst at Eurasia Group, a political risk adviser. “It will feel compelled to take revenge in order to signal to Israel that attacks are not free.”
At the same time, Rome said: “Iran must also ensure that such retaliation does not make it politically impossible for the West to press ahead with the re-entry of the JCPOA.”
Behrouz Kamalvandi, a spokesman for the civilian nuclear program, told Iranian state television that the power supply at the Natanz facility had been cut. He said there was no loss or damage. But Iran has sometimes offered such assessments immediately after the sabotage in order to revise them later.
Malek Shariati Niasar, an Iranian lawmaker who serves as spokesman for the parliament’s energy committee, said on Twitter the outage was “very suspicious” and pointed to the possibility of “sabotage and infiltration”.
The blackout came less than a year after a mysterious fire devastated another part of the Natanz facility, about 155 miles south of Tehran, the capital. Iranian officials initially downplayed the effects of the fire that destroyed an above-ground facility for assembling centrifuges, but later admitted it had caused significant damage.
The blackout came a day after Iranian officials praised the inauguration of new, advanced centrifuges housed in a site built after the Natanz fire.
Some Iranian experts rejected initial speculation that a cyber attack could have caused the blackout. The Natanz complex has its own power grid, several backup systems and security layers to prevent such an attack from shutting down its system abruptly.
“It is difficult to imagine that it was a cyber attack,” said Ali Vaez, the Iranian project manager at the International Crisis Group. “The likely scenario is that it will target the facility either indirectly or through physical infiltration.” The intelligence officials said it was actually a detonation of explosives.
While there is no direct dialogue between Iran and the United States during the talks in Vienna, the other participants in the agreement – Great Britain, China, France, Germany and Russia under the chairmanship of the European Union – take part in a kind of shuttle diplomacy.
One working group is looking at lifting the Trump administration’s economic sanctions, while another is looking at how Iran can return to conditions that limit the enrichment of enriched uranium and the centrifuges required to manufacture it.
Iran has said its nuclear ambitions are peaceful.
It has also said that while it intends to steadily resume the nuclear activities banned under the agreement, it could easily reverse course if the sanctions are lifted.
On Saturday, Iranian President Hassan Rouhani celebrated the new centrifuges that will reduce the time it takes to enrich uranium, the fuel for atomic bombs. But Mr. Rouhani also insisted that Iran’s efforts were not aimed at making weapons.
“When the West looks at the morals and beliefs that exist in our country, they will find that they should not be worried and sensitive to our nuclear technology,” Rouhani said in remarks by Iranian news agency Mehr.
The new centrifuges were inaugurated on Iran’s National Nuclear Day, an annual event to demonstrate the country’s advances in nuclear technology despite its economic isolation. The celebrations even included the debut of a music video in which scientists in white robes stood next to centrifuges holding photos of murdered colleagues.
Secretary of Defense Austin was in Israel on Sunday for talks with Prime Minister Benjamin Netanyahu and the country’s Secretary of Defense Benny Gantz.
It was unclear whether they were discussing the Natanz attack.
Speaking at the meeting, Mr. Gantz said, “We will work closely with our American allies to ensure that any new deal with Iran safeguards the vital interests of the world and the United States, prevents a dangerous arms race in our region, and protects the State of Israel . “
The United States and Israel have a history of covert cooperation dating back to the administration of President George W. Bush to disrupt Iran’s nuclear program.
The most famous operation under this collaboration, code-named “Olympic Games”, was a cyberattack that became known during the Obama administration and deactivated nearly 1,000 centrifuges in Natanz. It was believed that this attack slowed Iran’s enrichment activities by many months.
The reporting was written by David E. Sanger, Eric Schmitt, Lara Jakes, Gerry Mullany and Patrick Kingsley.