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Iran Conflict 2026
4JUN

Tehran texts diverge from Washington's five points

3 min read
11:25UTC

Iran's counter to the US five-point proposal, reported by Haaretz on 18 May, offers domestic uranium dilution and a 10-year moratorium against Washington's 20-year demand, while Bulletin of the Atomic Scientists satellite analysis estimates up to 540 kg of 60%-HEU may already sit at Isfahan, 100 kg above the MOU's surrender figure.

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Key takeaway

Two governments are bargaining over a stockpile no inspector can count.

Haaretz reported on 18 May 2026, citing a regional source, that Iran's counter to the US five-point proposal offers domestic dilution of its enriched-uranium stockpile rather than transfer outside the country, and a 10-year enrichment moratorium against the US 20-year demand 1. The US text, relayed by Tasnim and Fars and aggregated by Euronews, would require Iran to operate one nuclear site and surrender its enriched-uranium stockpile 2. Iran's own 10-point counter-proposal, transmitted on 10 May, was rejected the same day .

The verification problem sits underneath both texts. François Diaz-Maurin, nuclear-affairs editor at the Bulletin of the Atomic Scientists, published satellite analysis on 18 May of a truck with 18 blue containers at the south tunnel entrance to Iran's Isfahan complex on 9 June 2025. The Bulletin estimated the load could carry up to 540 kg of 60%-enriched uranium, above the 440 kg figure the US MOU was built to recover 3. A former Israeli intelligence official had already assessed that the June strikes left Iran's nuclear capacity intact ; the Bulletin's satellite work corroborates the inventory side of that claim.

The gap means more than 100 kg of weapons-relevant material. The IAEA, locked out of Iran since the unanimous Majlis suspension vote on 11 April , has lost what its inspectors call continuity of knowledge. Neither the Bulletin's upper-bound estimate nor any Iranian dilution programme can be independently checked. A signed deal pegged to a 440 kg surrender therefore leaves up to 100 kg unaccounted for under an Isfahan mountain that no inspector can enter. The headline demand of the entire US framework may already be priced against a stale inventory, which is the kind of architectural problem that does not get fixed by adjusting timelines.

Deep Analysis

In plain English

Nuclear negotiations between Iran and the US are deadlocked on two specific technical questions. First: where does Iran's stock of near-weapons-grade uranium go? The US wants it removed from Iran entirely. Iran wants to dilute it inside the country. Second: how long does Iran agree not to enrich uranium? Iran proposes 10 years; the US demands 20. A separate problem: a scientific organisation called the Bulletin of the Atomic Scientists published satellite images suggesting Iran has 540 kg of near-weapons-grade uranium hidden at its Isfahan facility 100 kg more than the amount the US deal was based on. UN inspectors have been locked out of Iran since April, so nobody can verify either the stockpile amount or any dilution Iran claims to do.

Deep Analysis
Root Causes

Iran's Supreme National Security Council shaped the domestic-dilution counter-proposal around three structural constraints, each distinct from political preference.

First, the IAEA lockout since 11 April means Iran cannot credibly commit to verified dilution on any timeline without re-engaging inspection architecture a concession Tehran would need to extract something substantial in return, not offer as a default starting position.

Second, the 540 kg Bulletin estimate, if accurate, means Iran holds 23% more weapons-usable material than the US MOU assumed. Proposing domestic dilution of an acknowledged 440 kg figure while holding an unacknowledged 100 kg buffer allows Tehran to appear to comply with the US demand while retaining a residual deterrent capability below the MOU's baseline.

Third, the 10-year versus 20-year moratorium gap reflects Iran's assessment of domestic political durability: a supreme leader who took office in March 2026 cannot credibly bind Iran for 20 years without a constitutional mechanism that does not currently exist.

Escalation

Iran's domestic-dilution counter combined with the Bulletin's 540 kg estimate makes a verifiable agreement structurally harder than the parties' public positions suggest. A deal that cannot be verified against a stockpile estimate with a 100 kg uncertainty range is not a deal; it is a pause.

What could happen next?
  • Risk

    The 100 kg discrepancy between the US MOU's 440 kg baseline and the Bulletin's 540 kg estimate means any domestic-dilution agreement cannot be verified without IAEA access which Iran has blocked since 11 April.

    Immediate · 0.83
  • Consequence

    Iran's domestic-dilution proposal is structurally designed to avoid the Libya-model precedent of foreign transfer; accepting it would mean the US concedes the sovereignty argument that has blocked every prior arrangement.

    Short term · 0.75
  • Risk

    A 10-year moratorium accepted without resolving the 100 kg verification gap gives Iran a decade to develop delivery systems before a politically-configured restart, narrowing the window for a follow-on agreement.

    Long term · 0.68
Sources:Bulletin of the Atomic Scientists·CBS News
Mentions:Iran →United States →Bulletin of the Atomic Scientists →Isfahan →IAEA →Haaretz →Euronews →Majlis →IRNA →South Africa →Arms Control Association →Tehran →Tasnim →Gaddafi →Libya →Washington →FAR →François Diaz-Maurin →
First Reported In

Update #102 · Iran signs Hormuz toll; Trump posts a cancelled strike

Bulletin of the Atomic Scientists· 19 May 2026
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Causes and effects
Caused by
Haaretz: strikes left Iran nuclear capacity intact
The IAEA lockout documented in ID:3398, which removed continuity of knowledge, is the structural condition under which Bulletin's 540 kg Isfahan estimate cannot be independently verified or refuted.
Occurred 18 May 2026
Read story →
This Event
Tehran texts diverge from Washington's five points
Both governments are now negotiating from texts that point in opposite directions, against a stockpile estimate the IAEA cannot verify because of an eight-month inspections lockout.
Led to
Khamenei orders the uranium to stay
Iran's pre-war offer to export half its 60%-enriched uranium (ID:3434) is directly reversed by Khamenei's 21 May uranium-stay directive.
Occurred 21 May 2026
Read story →
Brent reprices around Khamenei's uranium directive
Iran's pre-war dilution proposal (ID:3434) was the diplomatic-optimism premise the market had been pricing; Khamenei's reversal of it on 21 May is what the IEA-spread closure registers as the new structural floor.
Occurred 22 May 2026
Read story →
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