For Iran's nuclear program, a month is longer than it sounds

Mint

01-07-2025

The furious debate over whether U.S. strikes obliterated Iran's nuclear program or only delayed its progress toward being able to build a nuclear weapon by a few months skips over a key component in the equation: Iran's political calculation.
If Iran were to make the decision to build a nuclear weapon, it would be betting that it can complete the job and establish deterrence before the U.S. and Israel intervene—through military action, economic pressure or diplomacy—to stop it.
A longer timeline increases the risk of being spotted or struck again, which could dissuade Iran from taking such a gamble in the first place. So measured on the Iranian nuclear clock, a delay of a few months could translate into a lot longer than it sounds if it keeps Tehran from moving ahead.
'If they start their breakout effort, and it takes them three more months, that's a lot of time to respond. It gives you time to detect it. It gives you time to mount a response," said Michael Singh, managing director at the Washington Institute for Near East Policy and a former senior official at the National Security Council. 'It's not nothing."
The 2015 international nuclear deal negotiated by the Obama administration, which granted Iran sanctions relief in exchange for limits on its nuclear program, was designed to keep Iran a year away from being able to produce enough fissile material for a nuclear weapon.
President Trump pulled the U.S. out of that agreement in his first term. Iran scaled up its nuclear work a year later and by May this year, it was producing enough fissile material for a nuclear weapon every month.
Before the war, the general assumption was it would take Iran a few months to make a crude weapon as powerful as the bomb dropped on Hiroshima and deliverable by truck or ship, and one to three years to make a warhead that could be fit atop a missile.
Some analysts are concerned thatthe attacks by Israel and the U.S. may have convinced hard-liners in Tehran that the only way to preserve the regime is to make a run at developing nuclear weapons.
'If Iran decides to weaponize, it will take more time than it would have otherwise," said Alan Eyre, a former State Department official and member of the U.S. negotiating team under the Obama administration that worked on the 2015 nuclear deal with Iran. 'But, paradoxically, we might have strengthened their resolve to seek a nuclear weapon now."
'They're going to be figuring out how to reconstitute some sort of defensive strategy, or at least create a new one, because the one they had doesn't work anymore," he said.
Nuclear experts and U.S. officials say Iran could have stashed away enough centrifuges and material to race for a bomb. Rafael Grossi, head of the International Atomic Energy Agency, in an interview with CBS's 'Face the Nation" on Sunday, said Iran has the industrial and technological wherewithal to resume enriching uranium in a few months.
U.N. atomic energy agency chief Rafael Grossi said Iran can resume enriching uranium in a few months if it wants.
'The capacities they have are there," Grossi said. 'They can have, you know, in a matter of months, I would say, a few cascades of centrifuges spinning and producing enriched uranium, or less than that. But as I said, frankly speaking, one cannot claim that everything has disappeared and there is nothing there."
Grossi's agency is responsible for inspecting Iran's nuclear sites but hasn't been able to visit the sites since the Israeli strikes on Iran began June 13.
Iran's options now include trying to reconstitute a covert nuclear program and produce a bomb as fast as possible. A second option would be to agree to a diplomatic path that limits their ability to build a weapon by ending its enrichment of uranium, which the Trump administration has pushed.
Iran could also try to split the difference: engage in nuclear diplomacy while quietly advancing its nuclear program. That would mean working in secret at sites hidden from international inspectors, which would make the task more cumbersome.
Trump and his administration say the U.S. airstrikes using 14 30,000-pound bombs and a salvo of cruise missiles have destroyed the facilities at Fordow, Natanz and Isfahan. If so, Iran would need new, hidden enrichment sites, as well as facilities to turn enriched uranium into metal for a bomb core and manage a covert program that can get nuclear scientists to the site without being spotted.
'Iran will never obtain a nuclear bomb, because Operation Midnight Hammer obliterated their nuclear capabilities," White House deputy press secretary Anna Kelly said when asked about Iran's prospects for rebuilding its nuclear program.
Iran has worked for decades on know-how relevant to developing nuclear weapons and has mastered most of the aspects of building a bomb, according to the IAEA and Iranian and Israeli officials.
The Trump administration says it destroyed Iran's nuclear facilities at Fordow.
Before the war, Iran had amassed a large stockpile of highly enriched uranium large enough for 10 nuclear bombs if further enriched. It would have taken about a week to convert enough of the 60% material into 90% weapons-grade enriched uranium for one nuclear weapon, according to the IAEA.
Iran had also tested out many of the components needed to build a bomb and kept that knowledge alive for a new generation of scientists through experiments and studies ostensibly designed for peaceful purposes.
The fate of the fissile material stockpile and how many centrifuges Iran still has remain unclear. Some may have been moved from Iran's nuclear sites before the U.S. attack.
The IAEA's inspectors lost the ability to track Iran's manufacturing of centrifuges due to restrictions Iran imposed in response to Trump's withdrawal from the 2015 deal.
Inspectors have also spent six years seeking the whereabouts of a vast array of equipment from Iran's decades-old nuclear weapons program that Tehran dispersed in 2018. It could include lines for making uranium metal and equipment for testing high explosives and other key equipment for making a bomb.
Iran's pre-2003 nuclear program aimed to produce a small arsenal of nuclear weapons deliverable by missile. Experts believe Iran has yet to seriously work on miniaturizing a nuclear weapon and integrating it onto a missile, which could take one to three years.
'This process of actually making a warhead is not just a physical process. It also comes down to the engineering," the Washington Institute's Singh said. 'There's a little bit more art, rather than just science, to that part of it."
The office of the U.S. Director of National Intelligence assessed in March that Iranian Supreme Leader Ayatollah Ali Khamenei hadn't reauthorized the program to develop a nuclear weapon he suspended in 2003.
What Khamenei decides in the wake of the attacks is now the biggest consideration in any timeline.
'We don't know if that is an actively running clock," said Eric Brewer, a deputy vice president at the Nuclear Threat Initiative and a former senior official at the White House National Security Council and National Intelligence Council. 'These timelines are in some ways evolving, and they depend upon what choices Iran makes next."
Write to Jared Malsin at [e-mail] and Laurence Norman at [e-mail]