The biggest unanswered question after the signing of the interim 14-point Iran-US Memorandum of Understanding is what becomes of Iran's stockpile of highly enriched uranium.
While the agreement ends hostilities and sets a framework for broader negotiations, it postpones the hardest technical issue: how Iran's nuclear programme will be brought under international oversight.
The United States has at times demanded that Iran halt all uranium enrichment. Iran insists it will not relinquish what it sees as its right to enrich uranium. The MoU addresses this issue through a dilution mechanism conducted under international supervision.
The fate of Iran’s nuclear programme, which US President Trump cited as his main reason for going to war, may carry the greatest potential to unravel the deal.
Trump has touted Iran’s commitment to never develop a nuclear weapon, but this largely repeats long-standing pledges by Tehran. Where the negotiations could falter is over what to do with Iran’s stockpile of near-bomb-grade uranium. Trump has said he wants it shipped out or destroyed. Iran wants neither, though it has indicated a possible willingness to dilute the material.
What does the MoU actually say?
The nuclear provisions are set out towards the end of the 14-point agreement.
Point 8 is the key section. Iran reaffirms it "shall not procure or develop nuclear weapons." The two sides agree that the fate of Iran's stockpiled enriched uranium (and other nuclear-related issues, including Iran's nuclear needs) will be "immediately addressed" in the final agreement to be negotiated within 60 days.
A minimum methodology specified is down-blending of highly enriched uranium on site under International Atomic Energy Agency (IAEA) supervision. US officials described this as a "floor, not the ceiling," calling Iran's concession to discuss diluting the stockpile a "major win," while noting they will push for more in final talks.
The enriched material stays in Iran for now, with further details on enrichment levels and other issues deferred.
This maintains a "status quo" approach in the interim rather than fully dismantling capabilities, unlike stricter prior demands.
What exactly is ‘downblending’?
Downblending simply means mixing highly enriched uranium with uranium that contains a much lower concentration of the fissile isotope U-235.
The uranium is not destroyed or discarded; instead, it is converted into material suitable for civilian nuclear fuel rather than weapons use.
The process is not new. Iran itself carried out limited downblending of its 60 percent-enriched uranium in 2024, according to confidential IAEA reports seen by Reuters, although inspectors said Tehran later resumed production of highly enriched uranium.
The process is already well understood and has been used in previous arms-control agreements, including after the Cold War and during earlier Iran nuclear arrangements.
What is the IAEA offering?
The MoU leaves most implementation details to the IAEA.
The IAEA said on Thursday that it was ready to begin defining the "concrete steps" needed to implement a US-Iran deal to end the Middle East war.
"Now it's for us to sit down with our American colleagues, our Iranian colleagues, and start formulating the concrete steps that will have to be taken," IAEA chief Rafael Grossi told reporters in Geneva.
"This is a very complex operation and it's not a secret so we will have to be very, very detailed," Grossi said, adding that the outcome would depend "on the political will of both sides".
"Anything can work when two sides decide that they want something to be done," he said, adding that they were looking to his organisation to tell "them what is needed".
The IAEA estimates that Iran had 440 kilogrammes of uranium enriched to 60 percent, close to the level needed for a bomb, as Israel and the United States launched their first attacks in June last year.
Iran suspended cooperation with the IAEA then and inspectors have not seen the material since.
The UN nuclear watchdog's governing board last week approved a Western resolution demanding that Iran immediately provide information and access to its uranium stockpile and production facilities.
Tehran slammed that resolution as "counter-productive" at a time when talks were going on, and charged it was "politically-motivated", something Grossi vehemently denied.
Regional unease
Israel and Arab states, especially Gulf countries like Saudi Arabia and the UAE, have long expressed deep concerns about Iran's nuclear programme.
Key issues include Iran's secrecy and non-compliance history, stockpiles of near-weapons-grade (60 percent) uranium, which shortens "breakout" time to weapons-grade material (90 percent) and potential for a nuclear-armed Iran to embolden regional proxies, shift power balances, or trigger proliferation.
These countries view highly enriched uranium as a direct threat, not just a civilian energy matter. The MoU's deferral of full resolution keeps tensions alive, as neighbours worry about any deal that leaves significant enrichment infrastructure or stockpile intact under Iranian control.
Downblending is a standard process that is reversible in theory but effectively neutralises weapons potential if done thoroughly and monitored.
Typically done at enrichment facilities under IAEA seals, cameras, and inspector oversight, experts note it can be done "on site" without export, as referenced in the MoU.
Stockpiles require significant effort and verification to prevent diversion. Analyst reports emphasise IAEA monitoring as critical to build confidence, given past Iranian non-compliance. Some view it as a concession, others see it as insufficient if enrichment resumes at scale.
Overall, the MoU buys time with a ceasefire and outlines a path, but leaves the most difficult nuclear details to final negotiations.
