WASHINGTON (Realist English). Since the US and Israeli war against Iran began in late February 2026, President Donald Trump has struggled to clearly define the conflict’s objectives, according to an analytical article in the journal Foreign Affairs.
His rhetoric has swung from demanding regime change to degrading Iran’s military power, and then to ensuring safe passage through the Strait of Hormuz.
Most often, he has focused on Tehran’s nuclear programme – a strange emphasis for a war that has barely touched Iran’s nuclear infrastructure, yet understandable for a politician who withdrew from Barack Obama’s 2015 nuclear deal in 2018 and boasted a year ago that he had “obliterated” Iran’s programme. “The DEAL that we are making with Iran will be FAR BETTER than the JCPOA,” Trump wrote on Truth Social in late April.
However, reaching such an agreement will be far more difficult than the president seems to realise. The main reason: since Trump first tore up the 2015 deal, Iran’s nuclear capabilities have advanced dramatically. Negotiations are currently focused on two elements – the length of a moratorium on enrichment and the fate of accumulated highly enriched uranium. Both are necessary, but both are insufficient. Over seven years, Iran has radically improved its centrifuge production and installation technologies, drastically reducing the time needed to produce bomb‑grade material. Moreover, international inspectors’ knowledge has become riddled with ever more gaps.
For his own image, Trump needs a deal that differs radically from the 2015 JCPOA. A 2026 agreement must go far beyond restricting enrichment and stockpiles. It must create new, detailed procedures allowing inspectors to understand Iran’s real potential and prevent covert movement toward a weapon. If this is not done, regardless of whether the US bombs Iran, how long any enrichment moratorium lasts, or where the uranium ends up, Tehran will emerge from the war even closer to a nuclear bomb than before.
Iran Has Learned to Sprint
As early as June 2025, Iran’s enrichment programme was seriously degraded by US and Israeli strikes during the so-called “12‑day war”: nuclear scientists were killed, underground facilities at Fordow and Natanz were destroyed. Yet Iran’s nuclear problem is more acute today than in 2015. That agreement limited not only the number of centrifuges, but more importantly their types and the ability to conduct research. After the US withdrew from the JCPOA, those restrictions fell away.
In the following years, Iran acquired technological know‑how in centrifuge production and operation – knowledge that cannot be bombed away. By June 2025, its best centrifuges were roughly six times more efficient than in 2015. Furthermore, Iran accelerated installation: in 2015 it could install about two “cascades” (groupings of roughly 170 centrifuges) per month; by 2025 it was doing so nearly three times faster.
As a result, Tehran needs much less time to produce bomb‑grade material, even if it has to rebuild its nuclear infrastructure from scratch. Under the previous JCPOA restrictions, Iran could have covered the distance to a weapon in about a year at a moderate pace. Supporters of the deal argued that this gave enough time to detect a breakout attempt and respond. But between 2018 and 2025, Iran learned to sprint. Consequently, even if Trump were to secure a complete halt to enrichment and the removal of all highly enriched uranium – far more stringent than the 2015 conditions – Iran could still finish the race more quickly.
The authors’ estimate (both have been involved in previous negotiations) is that even if the war destroyed all centrifuges at Natanz and Fordow, Tehran would need closer to six months than a year to install more advanced machines elsewhere and produce enough material for one bomb. The timeline would shorten further if Iran retains thousands of kilograms of lower‑enriched uranium.
Gaps in Knowledge: Covert Sites and Weaponisation Research
Iran’s declared nuclear sites lie in ruins. But there is great uncertainty about whether the country possesses other, hidden facilities. Iran has a long history of clandestine enrichment – both known plants (Natanz and Fordow) were built in secret. In early 2025, Tehran announced plans to build a third underground facility at Isfahan, and pre‑war satellite imagery heightened fears that another large facility might be under construction near Pickaxe Mountain close to Natanz. The IAEA has not visited these sites, and their status – along with that of any other undeclared facilities – remains unknown.
In 2003, after Natanz was exposed, Iran temporarily agreed to the Additional Protocol – a document specifically designed to uncover hidden activities. The 2015 JCPOA explicitly required Iran to implement the Additional Protocol and strengthen oversight of centrifuge production. By tracking each manufactured centrifuge, inspectors could confirm that all were installed in declared, monitored facilities and not diverted to unknown locations.
The centrifuge‑monitoring programme continued after the US withdrawal from the deal, but collapsed in 2021 when Iran halted cooperation in retaliation for the assassination of its nuclear scientist by the Mossad. Since then, Iran has produced tens of thousands of centrifuges. Most were probably installed at Natanz and Fordow, but if even a few hundred were diverted to secret facilities, they could quickly turn low‑enriched uranium into weapons‑grade material.
The JCPOA focused mainly on restricting enrichment rather than weapon assembly – because controlling enrichment is easier than tracking weapon‑related activities (computer modelling, explosive testing, warhead design), which can be carried out in small laboratories indistinguishable from ordinary research facilities. For years, US intelligence assessed that Iran was not conducting key weaponisation work. Section T of the JCPOA sought to limit weapon‑design activities, but the enforcement mechanism was vague.
The nature of the threat has changed, however. Earlier, the main obstacle was obtaining fissile material; now that Iran has accelerated enrichment, it is possible to concentrate on weapon assembly. In 2024, US intelligence agencies quietly removed from their annual report the long‑standing assessment that Iran was not pursuing such work. Preventing and detecting weaponisation is difficult, but the world can no longer avoid it. Securing the necessary access for inspectors would have been challenging under any circumstances, and it is even harder now: Iran claims that IAEA inspections facilitated the espionage that led to the 2025‑2026 strikes on its facilities.
What Constitutes a “Good Deal”?
Ending the war diplomatically remains in the US national interest. But what worked in 2015 is no longer enough. Removing uranium enriched to 60% (what Trump calls “nuclear dust”) would eliminate the most pressing concern. A full five‑year suspension of enrichment, reportedly proposed by Iran, would go beyond some JCPOA restrictions. Yet a deal focused only on enrichment and stockpiles can no longer solve the problem. A good agreement must now address:
- Iran’s improved enrichment technology – faster centrifuges and accelerated installation.
- The potential for covert activity – the possibility of enriching at undeclared facilities.
- The ability to convert uranium into deployable weapons – weaponisation activities.
To achieve this, a new deal must:
- Require Iran to resume implementation of the Additional Protocol, which is designed to help the IAEA find covert facilities.
- Instruct inspectors to make the most complete possible accounting of all centrifuges produced by Iran since 2021, when it ended enhanced monitoring. The fact that many production facilities are now in ruins will severely complicate this task.
- Ensure verifiable information about non‑nuclear research and military activities that could have weapons applications, and grant the IAEA the right to inspect military sites. Iran will resist, but uncertainty about the agency’s authority to investigate suspicious activities must be resolved now, not left for the future.
A Troubling Signal
The Trump administration’s almost complete silence on the role verification and IAEA monitoring must play in any deal is a very troubling sign. Overall, the entire US military campaign has been characterised by a lack of advance planning: neither the likely trajectory of the conflict nor its impact on the global economy, Washington’s closest alliances, or US credibility in general have been sufficiently thought through. It would be a grave mistake if the same lack of attention to detail pervaded the effort to negotiate a new nuclear deal.
Matthew Sharp — Senior Fellow at the Center for Nuclear Security Policy at the Massachusetts Institute of Technology
Nate Swanson — Director of the Iran Strategy Project at the Atlantic Council
