As Washington and Tehran remain divided over whether international inspectors can verify Irans compliance with its nuclear non-proliferation commitments, former officials say the scale, scope, and level of site access will be critical to the success of any future monitoring process.

The details of those arrangements have not yet been defined, although Rafael Grossi, Director General of the International Atomic Energy Agency, said the UN watchdog would work to determine the when, how, and where of inspections very soon.

But experts say that does not mean the agency has not already prepared a list of priorities for any potential future inspections.

Laura Rockwood, a former IAEA negotiator on Irans nuclear file, told Radio Free Europe/Radio Liberty: They almost certainly have a plan for what they will do when they go back, what the priorities are, and where they want to go first, second, and third.

Rockwood, who took part in high-level negotiations on Iran during a 28-year career at the IAEA before retiring in 2013, added: The key thing is finding out exactly where the enriched uranium is. I would be willing to bet they have a plan ready for the day they need to return.

Uranium downblending could open new disputes

While US President Donald Trump has said Iran agreed to the highest level of nuclear inspections, Tehran insists it does not plan to allow such inspections.

Article 8 of the US-Iran memorandum of understanding states that both sides agreed to a minimum methodology under which Irans stockpile of highly enriched uranium would be downblended on site under IAEA supervision.

But the details of how this step would be carried out could themselves become a source of disagreement.

Matthew Sharp, who served as director for Iran nuclear issues at the US National Security Council from 2021 to 2022, told Radio Free Europe/Radio Liberty: If IAEA inspectors are able to measure and characterize both the highly enriched and low-enriched material before downblending, then simple calculations will provide a good understanding of the final product. They would then want to take measurements to verify the product and seal it for future accounting.

Sharp, now a senior fellow for nuclear affairs at the Center for International Studies at MIT, added: But if Iran carries out the downblending process itself and then presents the product to inspectors, it would be extremely difficult to know how much highly enriched uranium Iran started with. That could create uncertainty over whether all of the 60%-enriched uranium or other enriched material was actually downblended, or whether some of it remained outside our knowledge.

For now, the location of roughly 450 kilograms of Irans highly enriched uranium remains unclear. Following US and Israeli airstrikes, the stockpile may be buried under rubble inside a fortified facility beneath a mountain, or Iranian authorities may have moved some or all of it elsewhere to conceal it.

But if the material can be successfully located and downblended, the next step would be preventing Iran from re-enriching it later.

Monitoring enrichment is the hardest test

The memorandum states that both sides agreed to discuss the issue of enrichment and other agreed relevant issues related to the nuclear needs of the Islamic Republic of Iran, based on a satisfactory framework to be agreed in the final agreement.

Experts told Radio Free Europe/Radio Liberty that verifying such a commitment would have to involve the IAEA.

Kelsey Davenport, Director for Nonproliferation Policy at the Arms Control Association, said: Any suspension of uranium enrichment is relatively meaningless if it cannot be verified, and if the IAEA does not receive the access needed to ensure there are no covert enrichment-related nuclear activities taking place elsewhere in the country.

She added: The level of access, the provision of information to the IAEA, and how quickly Iran complies with agency requests for access will all be extremely important.

Davenport said that once enrichment levels are reduced to below 5%, the material becomes safer to move abroad and could be stored in an international fuel bank in Kazakhstan.

The idea of removing downblended uranium from Iran appears to have attracted interest among US officials. During a recent background call with reporters, one official said dilution inside Iran represents the minimum, adding: We will push for more than that.

A senior US official said Washington would rely heavily on the IAEA and US technical teams to verify implementation. We are not in the trust business, the official said.

The IAEA has previously verified Irans compliance with its commitments under the Nuclear Non-Proliferation Treaty, which Tehran ratified in 1970, as well as under the 2015 Joint Comprehensive Plan of Action.

Lessons from the past will shape future monitoring

Experts say many lessons have been learned from previous experience, highlighting the importance of the IAEAs Additional Protocol, which provides broader verification and monitoring tools.

Rockwood, now a senior fellow at the Vienna Center for Disarmament and Non-Proliferation and the principal author of the protocol, said: Under the Additional Protocol, instead of routinely being limited to nuclear material and facilities, we gained access to information and sites related to the entire nuclear fuel cycle, including centrifuge production.

She added: If you know roughly how many centrifuges they can manufacture, then you want to know where they are, and we can request that kind of access under the Additional Protocol.

Iran signed the Additional Protocol in 2003 but never sent the IAEA the formal letter required to bring it into force.

Tehran applied its provisions provisionally between 2003 and 2006, and again for a period during implementation of the JCPOA. But Rockwood noted that there were many indications of Iranian non-compliance during that time.

She said that situation may continue, with additional complications.

Iran has suspended IAEA access to sites that were struck by US and Israeli attacks on its nuclear facilities in June last year. That disrupted what Rockwood calls continuity of knowledge, meaning the agency lost the ability to track what Iran possesses and where those materials are located.

The scale of the damage also remains unclear, which could further complicate access to the sites, along with the possible presence of unexploded ordnance in some locations.

There will be uncertainty, and there will probably be more uncertainty than there was before. In fact, I expect that to be the case, Rockwood said. Yes, it will be an extremely difficult task.