With the rest of the world distracted by wars in Gaza and Ukraine, Iran has moved closer than ever to the ability to produce several nuclear weapons, installing 1,400 next-generation centrifuges in recent weeks inside a facility buried so deep that it is all but impervious to bunker-busting bombs.
The sharp technological upgrade goes hand in hand with another worrisome change: For the first time, some members of Iran’s ruling elite are dropping the country’s decades-old insistence that its nuclear program is entirely for peaceful purposes. Instead, they are publicly beginning to embrace the logic of possessing the bomb, arguing that recent missile exchanges with Israel underscore the need for a far more powerful deterrent.
In interviews with a dozen American, European, Iranian and Israeli officials and with outside experts, the cumulative effect of this surge appears clear: Iran has cemented its role as a “threshold” nuclear state, walking right up to the line of building a weapon without stepping over it.
American officials are divided on the question of whether Iran is preparing to take that final step or whether it will determine it is safer — and more effective — to stay just on the cusp of a weapons capability, without openly abandoning the last of its commitments as a signer of the Nuclear Nonproliferation Treaty.
Most officials spoke on the condition of anonymity because so much about Iran’s nuclear program, from assessments of its status to secret efforts to infiltrate and slow it, is highly classified.
And they caution that while Iran could now produce the fuel for three or more bombs in days or weeks, it would still take considerable time — maybe 18 months — for Iran to fabricate that fuel into a warhead that could be delivered on missiles of the kind it launched at Israel in April.
But Iran’s nuclear expansion comes at the most delicate of moments.
The Iranians are acutely aware that the United States is determined to avoid a broadening of the conflict in the Middle East, and there have been back-channel messages between Washington and Tehran to underscore the dangers. The Iranians themselves, one senior administration official said, know how much they have to lose if the war spreads.
Yet as one European diplomat involved in discussions with Tehran put it, if the Iranians had been enriching uranium at current levels just a few years ago, when the region was not such a tinderbox, Israel would almost certainly be considering military options to strike Iran’s nuclear facilities.
Prime Minister Benjamin Netanyahu of Israel, who came right to the edge of ordering such action on several occasions in the past, has said little about Iran’s recent buildup, preoccupied by the war with Hamas in Gaza and the risk that it will spread to open conflict with Hezbollah on the border with Lebanon. There are now indications from Israeli officials, however, that they are focusing anew on Iran’s recent advances.
They are also focusing on the change in the way Iran talks about its long-running nuclear program, which Israel — sometimes with the active participation of the United States — has tried to cripple in recent years.
As Iranians prepare to go to the polls on Friday to elect a successor to President Ebrahim Raisi, who was killed in a helicopter crash last month along with the foreign minister, top Iranian officials have dropped the ritual assurances that Iran has only peaceful uses in mind for its nuclear program. One official close to Iran’s supreme leader recently declared that if Iran faces an existential threat, it would “reconsider its nuclear doctrine.”
Israel’s defense minister, Yoav Gallant, raised Iran’s nuclear surge in meetings this week with Secretary of State Antony J. Blinken, Defense Secretary Lloyd J. Austin III and the C.I.A. director, William J. Burns, people familiar with the meetings said.
In April, Iran had fired hundreds of missiles and drones at Israel, most of which Israel intercepted. But the attack, which was retaliation for an Israeli strike that killed several Iranian armed forces commanders at Iran’s embassy compound in Syria, was a serious escalation. The Iranians most likely emerged from the experience determined that the country needed a more potent deterrent, American officials and outside experts have concluded.
“Iran is sending a clear message that if the pressure of sanctions continues, if assassination of its commanders continues and if Washington or Israel decides to tighten the noose, it will then break all the chains,” said Hossein Alizadeh, a former Iranian diplomat who defected 2010. He spoke from Britain, where he now lives.
Independent estimates based on production statistics from the International Atomic Energy Agency, which still has limited access to Iran’s facilities, the country has now enriched enough uranium at 60 percent purity — which can be converted to bomb-grade fuel in days or weeks — to make at least three weapons.
David Albright, a nuclear expert, said in an interview that once Iran finishes installing the new centrifuges in Fordow, its underground facility, Iran should be able to double that inventory in a matter of weeks or months.
Even though it would still take more than a year to actually produce a weapon, the question is whether American or Israeli spy agencies would detect the move and be able to stop it.
In a statement issued on Monday, the United States, Germany, Britain and France underscored the dangers.
“Iran is growing its stockpile of high-enriched uranium to levels unprecedented for a state without a nuclear weapons program,” the countries said, adding that “such activity has no credible civilian justification.”
Facilities Left in Place, and a Deal Abandoned
The last time Washington felt it faced a true nuclear crisis with Iran was 2013, when President Barack Obama dispatched Mr. Burns, then a top State Department official, and Vice President Joseph R. Biden Jr.’s national security adviser, Jake Sullivan, to explore the possibilities of a deal with the newly elected Iranian president, Hassan Rouhani.
Mr. Burns and Mr. Sullivan — who today, in very different roles, remain key players in the decision about how to deal with Iran’s expanding capabilities — emerged with a six-month deal to restrain the Iranian program in return for billions of dollars in sanctions relief. An acrimonious, on-again-off-again negotiation followed for a permanent deal, and one was struck in the middle of 2015.
Under its terms, 97 percent of Iran’s nuclear fuel was shipped out of the country to Russia, which at the time was working alongside the United States, the European Union, Britain, France, Germany and China to keep Iran from obtaining a weapon.
But there was a weakness in the deal, acknowledged by negotiators at the time.
Iran insisted that it had to hold onto its major enrichment facilities, resisting American and European demands that they be dismantled. So the underground facility at Fordow remained, spinning nonnuclear material — a concession that the lead American negotiator referred to at the time as a “bitter pill.”
So did the main enrichment site at Natanz, which is much closer to the surface and easier to destroy. (Iran is now building a deep-underground facility at Natanz, but it will not be ready, American intelligence officials estimate, for several years.)
While the U.S. and Israeli air forces often practiced what it would take to bomb Fordow, even building a mock-up of the site in the Nevada desert, military officials say it would take repeated, precise strikes by the United States’ largest “bunker buster” to reach down that deep.
For all the recriminations nine years ago from Republicans in Congress about the nuclear agreement, Iran initially stuck to its terms, limiting its production to token amounts of nuclear fuel. I.A.E.A. inspectors came and went with regularity, and while there were arguments about reconstructing the history of Iran’s past activities, the agency’s cameras provided a 24/7 eye on the chain of custody of Iranian fuel.
And, largely out of the sight of inspectors, Iran developed its new IR-6 centrifuges, able to produce fuel far faster than the old IR-1s that it struggled with for years, preparing for the day when, under the provisions of the agreement, it could install the new machinery.
Then President Donald J. Trump abandoned the 2015 accord. He argued that the re-imposition of sanctions would break the Iranian regime and predicted that the country would beg for a new deal.
Mr. Trump was wrong on both counts. The Iranians slowly began reactivating the plants. They removed some cameras and barred some inspectors. And they began enriching to 60 percent purity — putting the country far closer to bomb fuel than when Mr. Burns and Mr. Sullivan were sent off for secret negotiations 11 years ago.
An effort by the Biden administration to reconstruct the key elements of the deal collapsed in 2022. Rafael Grossi, the director general of the I.A.E.A., said after a recent trip to Tehran that the 2015 deal that Mr. Trump pulled out of is now dead.
“Nobody applies it, nobody follows it,” he told a Russian newspaper recently. “There have been attempts to revive it here in Vienna. But unfortunately, although they were relatively close to success, they failed for reasons unknown to me.”
Denials of Weapons Plans Begin to Crack
Iran has insisted that it cannot manufacture or use nuclear weapons because of a 2003 “fatwa,” or religious edict, issued by the country’s supreme leader, Ayatollah Ali Khamenei. The country said the fatwa remained in effect even after Israel stole, and then made public, a huge archive of Iranian documents that made plain the country was trying to design a weapon.
American officials say there is no evidence of a current effort to weaponize Iran’s near-bomb-grade uranium; Israelis argue that such efforts are indeed underway, under the guise of university research.
For Iran, the risks of moving to weaponization are high. While Iran has removed or deactivated some of the I.A.E.A.’s cameras, it is clear that the program is deeply penetrated by Israeli, American and British intelligence services.
The cat-and-mouse game with inspectors and Israeli and Western spies has been going on for years. But the recent nuclear expansion can be traced to the missile launches in April, when Iran and Israel went to the brink of war.
Soon after, three senior officials with close ties to Mr. Khamenei began declaring that Iran’s no-weapons doctrine was reversible if the country faced an existential threat. (Shiite Islam allows clerical scholars to reverse edicts and fatwas to reflect the demands of current times.)
The officials were Kamal Kharazi, an adviser on foreign policy to Mr. Khamenei and a former foreign minister; Abbas Araghchi, a prominent diplomat who served as deputy foreign minister and a nuclear negotiator for the 2015 nuclear deal with world powers; and Gen. Ahmad Haq Taleb, a member of the Revolutionary Guards Corps who serves as the commander for protecting and defending Iran’s nuclear sites.
If Israel threatened Iran’s nuclear facilities, General Haq Talab said in a speech in mid-April, “it’s entirely possible and imaginable that the Islamic Republic will reconsider its nuclear doctrine and policies and reverse its previously stated positions.”
A few weeks later, Mr. Kharazi told Al Jazeera that Iran had the capacity to produce a nuclear bomb, but that it has not decided to do so.
“If Iran’s existence is threatened, we will have no choice but to reverse our nuclear doctrine,” he said.
And in late May, Mr. Araghchi said at a conference in Doha, Qatar, that Israeli attacks “could force others to rethink their security calculations and their nuclear postures.”
The statements seemed coordinated, or at least a reflection of the debate taking shape within Iran’s power circles about whether it was time to weaponize the nuclear program and build a bomb, according to four Iranian officials, including diplomats and members of the Revolutionary Guards. All were privy to the continuing strategic debate.
Sharp divisions remain, but “at this point many Iranians are starting to believe and say out loud that building nuclear deterrence given all the threats we face is not just a military strategy,” said Mehdi Chadeganipour, who served as an adviser to former President Mahmoud Ahmadinejad. “It is pure common sense.”
