Big gaps in intelligence on Iran’s nuke program threaten push for quick deal

President Trump is calling for Iran to “go fast” to secure a new nuclear accord. But for any deal to work, Tehran will have to account for exactly what nuclear program hardware it has produced and stowed away.

There are critical gaps in the world’s understanding of Iran’s nuclear inventory. Tehran in recent years has restricted United Nations atomic agency oversight of its nuclear activities—a key requirement under the 2015 accord, and stifled an agency probe into undeclared nuclear material found in the country. At various points, it has removed cameras intended to monitor key parts of its nuclear infrastructure and effectively banned inspectors from those sites.

As a result, the International Atomic Energy Agency has since September 2023 said that it no longer has fully updated information about a range of Iran’s nuclear work and can’t confirm Tehran’s claim that its program is purely for peaceful purposes. U.S. Special Envoy Steve Witkoff has said the Trump administration’s red line is to prevent Iran from being able to produce a nuclear weapon.

U.S. intelligence officials said last month they don’t believe Iran has made a decision to build a nuclear weapon but U.S. officials think it would only take a few months for Tehran to build one.

Iran has stopped the agency from inspecting nonnuclear sites since 2021, curtailing the IAEA’s insight into Iran’s ability to build a bomb. But IAEA Director General Rafael Grossi said this week the Iranians “aren’t far away” from being able to do it.

U.S. and Iranian officials are set to convene in Rome for a second round of discussions on Saturday, after meeting in Muscat last weekend for the highest-level talks between the two sides since 2017.

This weekend’s talks are expected to include discussion on a timeline for negotiations and potentially a general framework for a new deal, U.S. and Iranian officials have indicated.

Implementing a new deal without having a clear inventory of what nuclear material and infrastructure Iran currently has would be extremely risky. Without that baseline, it is next to impossible to ensure that Iran is complying with detailed limits on its nuclear enrichment under a deal.

“Trump’s given a two-month deadline to get a deal done,” said David Albright, a former weapons inspector who heads the Institute for Science and International Security think tank. “Iran needs to start cooperating more fully with the IAEA in order to develop confidence that any deal is water-tight.”

After Grossi visited Iran this week, officials said it isn’t yet clear whether Tehran will provide the detailed information the agency is seeking about Iran’s nuclear activities. Discussions are continuing. Grossi called on Iran to step up cooperation to show its nuclear program is peaceful.

Iranian Foreign Minister Abbas Araghchi said on Thursday the IAEA can play an important role in resolving the nuclear file. But he warned the agency to steer clear of the “politics and politicization,” Tehran has accused the IAEA of in the past for putting pressure on Iran over its nuclear work.

The U.S. and European powers have repeatedly called on Iran to step up its cooperation with the agency in recent years. They have censured Iran for not doing so at the IAEA three times since November 2022.

The critical gap in IAEA knowledge of Iran’s nuclear program is Iran’s inventory of centrifuges, machines that spin uranium into higher levels of enrichment.

Under the 2015 nuclear deal, Iran installed cameras at factories producing the key parts of centrifuges, part of a strict monitoring regime of Iran’s nuclear sites and related facilities. The idea was to know exactly how many centrifuges Iran had produced to ensure they couldn’t breach limits on fissile material production.

In 2021, three years after the Trump administration quit the nuclear deal, Iran stopped handing over to the agency footage and measurements from the cameras installed at the facilities.

Later that year, following an attack on its Karaj centrifuge site, which Tehran blamed on Israel, Iran went several months without cameras monitoring its centrifuge production. As pressure on Iran’s nuclear program mounted, Iran removed cameras monitoring its centrifuge sites again in June 2022. It only started to replace some a year later.

The IAEA still has frequent access to Iran’s two enrichment sites and is confident Iran hasn’t diverted fissile material from them.

However, the agency said in February that it has “lost continuity of knowledge” of Iran’s production and inventory of centrifuges and their key parts: rotors and bellows. If Iran secretly stowed away a few hundred of its more advanced centrifuges, it would retain a critical component of its ability to produce weapons-grade enriched uranium.

The agency can work to try to rebuild a credible picture of Iran’s centrifuge inventory, experts say. It can carry out a range of inspections and tests to build a picture of how much Iran could have produced and match it against Iran’s declared inventory. But this work could take as much as six months, according to one European diplomat working on Iran’s nuclear file and the agency is unlikely to get a complete picture.

Iran must settle another issue before a deal can be implemented: resolving an IAEA probe into undeclared nuclear material found in Iran.

The issue is a major political challenge for Iran’s leadership. The nuclear material likely originated in past nuclear weapons work Iran did in the 1990s and 2000s, the agency and Western officials think. But Tehran has repeatedly denied it has ever conducted such work. Without detailing why it has the material and where it is now, Iran may not be able to close down the probe.

One of the main criticisms in Washington of the 2015 nuclear deal was that it didn’t force Tehran to detail its past nuclear work. Those concerns remain in Congress, which may have to ratify a new deal.

Trump has said that he wants to negotiate a nuclear deal but has warned he would hit Iran militarily if it refuses a deal. On Thursday he denied he had waved off an Israeli attack to strike Iran’s nuclear plants but said he is “not in a rush to do it.”

Write to Laurence Norman at laurence.norman@wsj.com