Iran-US war: Mohsen Rezaei says ‘not a single gram of enriched uranium will leave Iran’ — what we know so far

Iranian Supreme National Security Council Secretary Mohsen Rezaei ruled out sending Iran’s enriched nuclear material abroad. In a post on X after meeting Pakistan’s army chief Asim Munir in Tehran, Rezaei said, “Not a single gram of enriched uranium will leave Iran.”

Rezaei had made similar remarks during a meeting with Pakistan’s Asim Munir in Tehran. In conversation with Munir, Rezaei described the stockpile as a national asset intended for domestic use, Iran International reported.

“…such materials constitute a major asset and national wealth for the Iranian people, intended for use within the country,” Rezaei was quoted by AFP as saying.

The Iranian leader demanded that all of Iran’s demands be met to move the negotiations forward. These conditions involve lifting pressure, threats and sanctions.

“There will be no negotiations until the United States takes steps to build trust. That process must begin with the full fulfilment of all Iran’s conditions,” Rezaei posted on X.

Iran ‘red line’

The US wants substantial restrictions on Iran’s uranium enrichment capabilities, while Tehran is prioritising relief from the US blockade and sanctions, alongside the restoration of maritime traffic through the Strait of Hormuz, as war in West Asia continues.

Iran has maintained that the uranium enrichment is for domestic purposes and wouldn’t be used to make a nuclear weapon. Leaders of the Islamic Republic have time and again emphasised Iran’s right to enrich uranium.

“Iran will never give up what it regards as its right to enrich uranium,” a senior Iranian official told Reuters early October, pushing back against US demands that Tehran significantly reduce its enrichment capacity as part of any agreement to end the war.

The official reportedly said that the US’ recognition of Iran’s right to enrichment was a “red line” for Tehran. Iran would “never give up its right to enrich,” the official said, although the details and scale of enrichment could be discussed later.

US Vice President JD Vance had earlier told Reuters that Iran would need to make a “meaningful” reduction in its enrichment capacity to satisfy US demands, questioning why Tehran needed uranium enriched to 60 percent if it did not intend to build a nuclear weapon. He said Washington wanted concrete action rather than assurances from Tehran.

What we know about Iran’s uranium reserves

The International Atomic Energy Agency (IAEA) estimates Iran possesses more than 400 kilograms of highly enriched uranium — enough for several nuclear weapons if further refined. These are primarily stored across key known sites in Isfahan, Fordow, and Natanz.

While Tehran denies pursuing nuclear weapons, the UN nuclear watchdog’s chief said concerns over its potential capabilities “have not been fully dispelled.” Tehran has asserted that its enrichment program is only meant to produce fuel for peaceful nuclear reactors.

According to the 2015 Joint Comprehensive Plan of Action (JCPOA) mandate, Iran’s enriched uranium stockpile must not exceed 300 kilograms (kg) of UF6 containing 3.67% uranium-235 (u-235) isotope “or the equivalent in other chemical forms.”

But the IAEA, according to a report by IAEA Director General Rafael Grossi, assessed that Tehran’s enriched uranium stockpile remains in the country.

The IAEA claimed that this stockpile includes 184.1 kg of UF6 containing up to 20% u-235 and 440.9 kg of UF6 containing up to 60% u-235.

According to US assessments, Iran halted its nuclear weapons program in late 2003. This program’s goal, according to US officials and the IAEA, was to develop an implosion-style nuclear weapon for Iran’s Shahab-3 ballistic missile.

The US alleged that before its June 2025 strikes on Iran, Tehran’s number of installed centrifuges, the mass and u-235 concentration of Tehran’s enriched uranium stockpile, and number of enrichment locations exceeded JCPOA-mandated limits.

According to the US Congress, Tehran’s expansion of an enrichment program beginning in 2019 has decreased the time needed to produce enough weapons-grade HEU for a nuclear weapon—an action frequently termed “breakout.”

Iran began limiting its enrichment-related activities and ceasing its work on heavy water-related projects under the internationally-agreed Joint Comprehensive Plan of Action (JCPOA). However, following the USA’s withdrawal from the agreement in 2018, the country began enriching uranium again.

Israel and the United States attacked Iranian nuclear sites in a 12-day June war in 2025, setting back the nuclear program but leaving its fate unresolved. Tehran has since declined to allow IAEA inspectors to resume their inspections.

In October 2025, Iran officially ended the 2015 JCPOA, declaring that all restrictions on its nuclear programme are now void.

What is highly enriched uranium?

Natural uranium consists mainly of two isotopes: U-238 and U-235. The latter is key to the fission reaction necessary for both nuclear power and weapons, but it occurs in low concentrations in raw uranium ore.

The material therefore needs to be enriched to increase the concentration of U-235, which is done using thousands of centrifuges spinning at supersonic speeds to separate the isotopes.