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Iran nuclear monitor Month by month

America and Israel have bombed Iran since 2025 to block Tehran’s path to nuclear weapons. ECFR’s interactive dashboard, updated monthly, assesses current evidence about Iran’s nuclear activities to determine which of six possible scenarios is most likely

Before the strikes After the strikes Download PDF

Author: Ellie Geranmayeh

Last updated: 29 September 2026

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Activity indicating which scenario is unfolding as of September 2026

↓ Scroll down for the introduction

Scenarios and
their implications

If Iran…

Neither rebuilds nor negotiates

Without monitoring, Iran could rapidly enrich its existing uranium stockpile to weapons-grade

Neither rebuilds nor negotiates

Threat Implications

Low

A deal caps and monitors the nuclear programme, buying the West time to react if there are signs of weaponisation

Iran commits to cap its civil nuclear programme under a new deal

Iran—either under the current leadership structure or a new one—reaches an agreement with America on the future of its nuclear programme before it starts rebuilding it in earnest. In the lead-up to an accord, Iranian officials may advance some nuclear activities to signal their intention to preserve the programme. At the heart of such a deal, Iran accepts restrictions on its nuclear activities and enhanced monitoring by International Atomic Energy Agency (IAEA), in return for economic relief and assurances that it will not be attacked.

The agreement could be a narrow US-Iran deal focused on nuclear issues, or a broader grand bargain. It may also connect Iran’s nuclear programme to a new regional consortium that provides greater confidence to the Middle East and the US over Iranian activities and intentions.

Why might Iran take this path?

Following the wars with the US and Israel since 2025, domestic political unrest and seismic economic problems, Iranian leaders might calculate that the best path for regime survival is a deal with the US that provides economic breathing room to ease domestic pressure, and remove the shadow of war and the threat of externally imposed regime change.

Restricting factors

Hawkish voices inside the US administration could derail diplomacy by pushing for maximalist demands, or Congress may spoil the final terms agreed by restricting sanctions relief to Iran.
There could be opposition to Washington implementing the agreement if there is a major human rights crackdown inside Iran, or if Iran conducts attacks against US allies.
Israel could oppose deal-making with Iran and influence the US president against a final accord.
Spoilers in Iran could harden Tehran’s position or push against prioritising talks over the nuclear programme. Instead, they may focus on reconstruction efforts and/or bolstering missile and drone capabilities to deter or prepare for future conflict.
Following widespread US and Israeli assassinations of Iranian leaders, there may not be a strong enough central state in Iran to negotiate and implement a deal with Washington.

Threat Implications

Medium

Without monitoring, Iran could rapidly enrich its existing uranium stockpile to weapons-grade

Iran neither significantly rebuilds its nuclear programme nor meaningfully negotiates

Since the June 2025 attacks, Iran has held off on a major rebuilding of its civil nuclear programme and weaponisation. It has also not entered into genuine negotiations with America on a nuclear deal, despite several mediation attempts. This scenario of not taking any action to rebuild or meaningfully negotiate over its nuclear programme could continue for a prolonged period but is ultimately unsustainable as domestic pressure will likely compel Iran’s leaders either to scale up or cap their nuclear activity.

Why might Iran take this path?

Leaders in Tehran may be unwilling to provide major concessions in nuclear negotiations after the war but may judge that a major rebuilding of its programme will hand Washington another pretext to renew military strikes with a larger coalition of countries.

The ruling elite may prefer to wait to keep its options open for the future of its nuclear programme. The political system may need time to forge a consensus on Iran’s long-term nuclear goals amid internal unrest, a new leadership, economic constraints and Israeli and US military threats.

Iran may continue prioritising strengthening its missile capabilities and conventional arsenal.

Restricting factors

Domestic hardliners, emboldened after the February 2026 war against the US and Israel, could pressure the new leadership to resume nuclear activities to recoup the costs incurred for sustaining the programme and to gain leverage in future talks.

Threat Implications

Medium

Iran could use parts of a rebuilt programme to dash to a nuclear bomb largely undetected, giving the West limited reaction time

Iran rebuilds civil nuclear programme without a US deal but with some transparency

Having been bombed twice amid negotiations with the US, Iran might begin rebuilding its civil nuclear programme regardless of its relationship with current or future US administrations. The leadership is only likely to have the political, practical and financial bandwidth to take this path after a sustainable ceasefire is put in place to end hot conflicts with America. In the absence of a broader nuclear deal with Washington, Tehran could signal the purely civilian nature of its nuclear programme by allowing more IAEA inspections and monitoring of its rebuilding.

Why might Iran take this path?

Following the 12-day war, Iranian officials vowed to rebuild the country’s nuclear programme “with greater strength” to meet civilian energy and health needs (ie, using nuclear reactors to produce medical isotopes). They also tied nuclear prowess to national pride and resistance to American hegemony. In February 2026, Iranian leaders showed they were prepared to again face war with the US and Israel, rather than accept Trump’s demands to end nuclear enrichment forever. Rebuilding the nuclear programme would increase leverage for future international diplomacy and keep the weaponisation option alive.

Restricting factors

The threat of detection and renewed American or Israeli military strikes will hang over any attempt to reconstitute the programme.
Iranian leaders’ awareness that having an advanced nuclear programme without a US deal and minimal international inspections invited military action in the past but failed to deliver sanctions relief.
Scarce financial resources and nuclear capabilities amid an economic downturn worsened by war and public discontent.
Restored UN sanctions, coupled with America’s tightening enforcement, constrict Iran’s ability to import the goods needed for rebuilding.

Threat Implications

High

Iran acquires a nuclear arsenal and can threaten to attack adversaries

Iran weaponises its nuclear programme

Either under the Islamic Republic or another leadership structure, the ruling class may decide to weaponise Iran’s nuclear programme, most likely in undeclared nuclear facilities rather than at the bombed sites already known to the international community.

To do so, they could take the following pathways:

Route one: If the 60% enriched uranium stockpile and some of the centrifuges survive American or Israeli bombings (and can be accessed), then Iran could enrich uranium to weapons grade. This could allow it to potentially rapidly produce enough weapons-grade uranium for nine to ten nuclear bombs.

Route two: Starting from scratch, Iran would need to enrich natural uranium to weapons-grade, manufacture and assemble new centrifuges, and build new facilities to process yellowcake—the concentrated uranium ore that forms the first step of the nuclear fuel cycle—into uranium gas for enrichment. This route for weaponisation is longer, requiring time and technical competence.

For both these pathways to provide serious deterrence, Iran would need to convert the weapons-grade uranium to metal, fabricate the metal into a core or pit, and fit it with an explosives package. Iran would also still need to invest resources into integrating a warhead and re-entry vehicle into a nuclear-capable ballistic missile delivery system (which could take several months to a year).

Route three: Iran could use its remaining 60% enriched uranium stockpile, convert it into metal without enriching it further, and fit it with an explosives package to produce a “crude” nuclear weapon. This would demonstrate it has entered the nuclear power club, but such a warhead would be far too big to fit on a missile, so its deterrence value would be negligible. Iran would also expose its secret nuclear sites in the process and face American and Israeli bombing in response. This is unlikely to be Iran’s preferred route.

Why might Iran take this path?

Iran’s new supreme leader—or any successor—may view weaponisation as the best insurance policy for regime survival, especially in light of the January 2026 mass protests and repeated wars with America and Israel, which Iranian officials view as intended to provoke regime change.

Restricting factors

American and Israeli deep intelligence and penetration of Iranian nuclear activities make Iranian advances nearly impossible to conceal without first being bombed.
If Iran tries to access its enriched uranium in buried facilities, America and Israel may resort to special ground operations to secure or remove the stockpile.
Rebuilding enrichment capacity from zero demands goods and technology that would be difficult for Iran to procure.
Iranian leaders may consider that the programme’s steep cost and potential to provoke another war could fuel greater public discontent and protests.
Opposition to Iran’s weaponisation from Arab states, China and potentially Russia would isolate Iran and leave it more vulnerable to American and Israeli attacks.
Iranian authorities recognise that nuclear status will not deter all US and Israeli strikes (just as it has not stopped cross-border strikes and skirmishes between nuclear-armed India and Pakistan).
Weaponisation risks provoking an American or Israeli use of tactical nuclear weapons.

In February 2026, Israel and America began pummelling Iran with new airstrikes that killed the country’s long-time leaders and triggered a broader regional war. One of President Donald Trump’s few consistently stated goals for this war was to ensure Iran “never” obtains a nuclear weapon.

For decades, Western governments saw Iran’s advancing nuclear programme, combined with its anti-Western stance and threats to Israel, as a danger to global stability. Israel and America assert they tried to stop that progress in June 2025 with the “12-day war”, but they clearly failed to settle the issue despite Trump’s claim that they had “obliterated” Iran’s nuclear programme. Pentagon officials later assessed that the strikes had set Iran back by only a year or two. The head of the UN’s International Atomic Energy Agency (IAEA), Rafael Mariano Grossi, judged that Iran’s technical capabilities remained largely intact and Tehran was still primed to weaponise its nuclear capabilities should it have decided to do so. Compounding this, the strikes backfired on oversight: Iran retaliated by further blocking monitoring of its nuclear programme through the IAEA.

The second US and Israeli air bombing campaign since February 2026 has—thus far—not significantly altered the nuclear balance. What it has changed is Iranian leadership dynamics. The assassinations of senior figures who helped establish the Islamic Republic of Iran in 1979 have brought to power a hardened, more militarised elite—one that is less bound by the late supreme leader’s religious ban on nuclear weapons. After being attacked twice while negotiating with Washington, Iran’s rulers may now see nuclear arms as survival insurance.

Yet the Islamic Republic’s future is far from certain. In January 2026, nationwide turmoil shook the country as political repression and economic misery eroded public tolerance towards the ruling elite. The regime survived by using unprecedented brutal force. The recent wars, including the US blockade of Iranian energy exports, have further damaged Iran’s economy. Against this backdrop, America and Israel have encouraged Iranians to revolt, hoping this can trigger regime collapse.

Faced with these crises, Iran’s nuclear programme could follow several paths. This ECFR interactive project explores the range of realistic scenarios ahead, tracing the actions that could indicate which scenario is unfolding and the warning signs policymakers should look out for. Any assessment of what comes next also requires an understanding of the state of Iran’s programme before the bombs fell.

The nuclear programme before June 2025 →

About the project

This regularly updated Iran nuclear monitor is developed in consultation with nuclear security experts, drawing on open-source intelligence, IAEA statements and satellite imagery analysis. Indicators track distinct, observable activities or declarations of intent—for example, diplomacy, enrichment or official nuclear policy—that collectively allow readers to assess which of the six scenarios is most strongly reflected by current evidence. The scenarios are designed to span the spectrum of most realistic outcomes for Iran’s nuclear programme following the US-Israeli strikes of 2025, ranging from a negotiated cap to covert weaponisation. No single indicator is conclusive on its own; the monitor is designed to be read across the full matrix. It is updated periodically as new intelligence and reporting become available.

Project team: Edited by Kat Fytatzi; digital and web design by Nastassia Zenovich; web development by Martin Tenev.

Acknowledgements

This project was brought to life through an extensive collaborative effort with ECFR’s Kat Fytatzi, Nastassia Zenovich and Martin Tenev. The author is deeply grateful to Kelsey Davenport, Director of Nonproliferation Policy at the Arms Control Association for her technical guidance on nuclear matters, which has been invaluable to the assessments presented here. Thanks are also due to the experts who provided peer reviews for this project, ECFR’s Dina Khadum and Sarah McCool for their excellent research support, and Julien Barnes-Dacey and Jeremy Cliffe for their guidance and commitment to our vision.

This project was realised with the support of Ploughshares and Fondazione Compagnia di San Paolo. Scientific Advisor: Fondazione CSF

Best experienced on a larger screen

Iran nuclear monitor Month by month

Iran commits to cap its civil nuclear programme under a new deal

Why might Iran take this path?

Restricting factors

Iran neither significantly rebuilds its nuclear programme nor meaningfully negotiates

Why might Iran take this path?

Restricting factors

Iran rebuilds civil nuclear programme without a US deal but with some transparency

Why might Iran take this path?

Restricting factors

Iran rebuilds an underground nuclear programme without a US deal

Why might Iran take this path?

Restricting factors

Iran loses control of its nuclear programme due to strikes or strife

Why might Iran take this path?

Restricting factors

Iran weaponises its nuclear programme

Why might Iran take this path?

Restricting factors

About the project

Acknowledgements