Can Iran still build nuclear weapons after the US bombing?

Times

23-06-2025

The 14 GBU-57 'bunker-busters' dropped by the Pentagon's B2 stealth bombers on Iran's nuclear facilities will have done a lot of damage, with about 200 tons of heavy munitions.
They may not have 'fully obliterated' all three sites at Natanz, Isfahan and Fordow as President Trump claimed, but they probably did cause 'severe damage' in the more modest assessment of the Pentagon.
That does not mean, however, that Iran's nuclear programme is dead and buried. Apart from anything else, somewhere in Iran is probably a deadly cargo of canisters in secure storage.
They contain just over 400kg of uranium enriched to 60 per cent purity — enough, with some extra enrichment, for about nine nuclear warheads. That level of enrichment means the uranium is 60 per cent made up of the U235 isotope needed to make the kind of bomb dropped on Hiroshima in 1945.
In the raw, uranium consists of 1 per cent U235 and 99 per cent U238 isotope. Weapons-grade uranium is 90 per cent U235.
To get from one to the other, a machine — of the sort the Iranians have at Isfahan — converts the uranium to uranium hexafluoride gas.
That gas is then taken to one of the two known Iranian enrichment facilities, at Natanz or Fordow. There it is passed through racks of centrifuges which spin at hundreds of times a second, threshing the heavier U238 to the outside and leaving behind the 'enriched' gas with its greater concentration of U235.
• Who are Iran's allies — and will any help after the US strikes?
The Israelis and Americans will be hoping that the bunker-busters — 12 dropped on Fordow, whose centrifuge chambers are buried 90 metres below ground, and two on the shallower Natanz — will have destroyed those centrifuges. They are sensitive and even the lesser strikes on Natanz by the Israelis at the start of their own bombing campaign may have put them out of use. Questions remain, however.
Did the US mission succeed?
Satellite imagery of the Fordow site in the aftermath of the bombing seems to show some holes in the mountain above it, which may be consistent with damage. One possibility is that the bombs did not manage to break into the chamber but collapsed it enough to have the required effect.
At Isfahan, the unit converting uranium to uranium hexafluoride, and the separate plant that converts the enriched gas back to metal to be turned into a warhead, are both believed to have been easier targets.
•
'The key thing is that the enrichment facilities and metal conversion facilities are now non-operational and potentially destroyed,' said Ian Stewart, a former Ministry of Defence specialist and now director of the James Martin Centre for Nonproliferation Studies at the Middlebury Institute in the United States. 'It will take weeks or months to reconstitute those capabilities.'
Are there hidden centrifuges?
Secondly, there is the question of whether the Iranians have more centrifuges hidden away elsewhere, allowing them to restart the programme fairly quickly.
'We have to assume the Iranians are competent and put aside a spare set of equipment,' Stewart said. 'They may also have set up small numbers of machines in unknown locations. So for planning purposes you have to assume it will take weeks or months for Iran to reconstitute the enrichment capability, not years.'
Iran has, of course, lost key members of its nuclear 'command and control'. Back in November 2020, Mossad, the Israeli intelligence agency, assassinated Brigadier-General Mohsen Fakhrizadeh, the Revolutionary Guards officer seen as the mastermind of the 'dual use' programme: one built overtly for civilian purposes, but compatible with a decision to build a bomb. He was ambushed and shot near his weekend villa outside Tehran by a robot-controlled machinegun on a pick-up truck.
Since the Israeli bombing began on June 13, at least ten prominent nuclear scientists, including Fereydoon Abbasi, a former head of Iran's Atomic Energy Organisation (AEOI), and many of the leaders of the Guards have also been killed.
However, the programme employs thousands of people, many of whom are experts in their fields.
'The Iranian nuclear programme is decades old and draws on extensive Iranian indigenous expertise,' Darya Dolzikova, a senior research fellow at the Royal United Services Institute, said.
'The physical elimination of the programme's infrastructure — and even the assassination of Iranian scientists — will not be sufficient to destroy the latent knowledge that exists in the country.'
Key to the future is the whereabouts of that 400kg of 60 per cent enriched uranium, which Stewart called 'the most valuable asset in Iran right now'.
Iran could fashion it into a large but crude nuclear device that could be transported by lorry, or, with a few centrifuges it had saved, convert some of it into a smaller nuclear weapon.
Will Iran risk all-out war?
Iran may or may not choose to escalate militarily, to try to show that it still has the military teeth and, indeed, necessary level of defiance to risk an all-out confrontation with the United States.
But in the medium term it has a huge question to answer that is both technical and political. Does it tell the International Atomic Energy Agency where those cylinders of enriched uranium are, as it is required to do under the nuclear non-proliferation treaty (NPT) to which — unlike Israel — it is a signatory?
If it does, it will no doubt fear that the information will make its way to Israel or the US. If it does not, and particularly if it withdraws from the NPT, that could prompt the European states — Britain, France and Germany — who are still signatories to the semi-defunct 2015 nuclear deal to trigger a 'snapback' mechanism. That would entail reintroducing more sanctions and renewing the UN ban on the nuclear programme.
The 2015 deal expires in October. President Trump still says he wants a new one — on his terms. An Iran that wanted peace at all costs would probably comply.
But the Iran that exists at present — the Islamic Republic — has so far refused to fold. It may, eventually, agree to more talks. But the United States and Israel will be wary that this is a play for time, until the nuclear deal expires, or just until Trump tires of the whole issue.