The US war was launched to make an Iranian bomb impossible. Instead, it has made one likely. Eight months on, Iranian officials who once called nuclear weapons forbidden now ask openly why they should not build one. Iran has not yet declared it has a bomb, but it now has more reason to want one and far fewer restraints on building one than at any other point in its history. Unless something changes, it will build one. Why have Tehran’s calculations shifted, and what would happen if it did?
How close is Iran?
US and Israeli bombing may have set back Iran’s nuclear infrastructure, but it has not removed the material that matters most. Before the June 2025 strikes the IAEA estimated that Iran had 440 kg of uranium enriched up to 60% purity, a short step away from the 90% needed for weapons grade; no other country has enriched uranium to such a high level without producing a nuclear weapon.
By the IAEA’s own calculations, about 42 kg of uranium is enough for one weapon if enriched further. Iran’s stockpile is roughly ten times that. No one outside Iran knows for certain where it is now. The IAEA believes much of it sits in tunnels at Isfahan, but its September 2026 report says it cannot establish the stockpile’s size or location. Inspectors were withdrawn after the US bombing in June 2025 and have had no access to any of Iran’s four declared enrichment sites since.
The IAEA also cannot verify if the material has stayed at 60%. In 2023 inspectors found particles enriched to 83.7%, which Iran blamed on “unintended fluctuations”. More recently, on the 12th of May 2026, Ebrahim Rezaei, an Iranian hardliner who is spokesman for the parliament’s national security and foreign policy commission, stated that enriching uranium to 90% was one of Iran’s options if it were to be attacked again.
Iran would not need to wait for a missile to carry such a weapon. A first-generation nuclear warhead is heavy, and shrinking one to fit on a missile is among the hardest steps in building a usable bomb. Iran has largely sidestepped that problem. Its Khorramshahr ballistic missile is reported to carry a warhead of up to 1,800 kg over a range of 2,000 km, far above the 500 kg payload that, under the Missile Technology Control Regime, already marks a missile as nuclear capable. A payload that large could take a crude, unminiaturised warhead. That matters: building a reliable delivery system is often the slower and harder part of becoming a nuclear power, and it is the part Iran has already done. The fissile material and a working warhead design remain the gaps.
Why the bombs haven’t worked
Twice in eight months the United States has bombed Iran’s nuclear programme and twice the programme has survived. After the June 2025 strikes President Donald Trump declared Iran’s main nuclear sites obliterated, but a preliminary assessment by the Defense Intelligence Agency suggested that Iran had been set back by just a few months.
This year’s conflict with the United States and Israel has done little better. Two months into the fighting, US intelligence found only limited new damage and judged that the time Iran would need to build a weapon had not changed. Bombs can destroy buildings, but not a stockpile reported to be buried 80 metres deep, and the strikes have left inspectors with no way of counting it. Iran stayed short of a bomb and was attacked anyway, a lesson Tehran is unlikely to forget.
Tehran’s shifting calculus
The constraint that has weakened most is political. In 2003, Iran’s then supreme leader Ayatollah Ali Khamenei issued a fatwa declaring nuclear weapons forbidden and officials have long cited it as proof of peaceful intent. However, since Khamenei was killed on the first day of the war, on the 28th of February 2026, his son and successor, Mojtaba Khamenei, has not publicly reaffirmed the ruling. Even during his September 2026 interview with Fox News, President Masoud Pezeshkian, whilst stating that nuclear weapons were religiously forbidden, could cite only the late leader and not the new one.
Into that silence has come open debate, a marked shift in a country where advocating nuclear weapons long risked looking like a challenge to the supreme leader. On the 18th of October Ahmad Naderi, a member of parliament’s presiding board, called for Iran to build and test a bomb and suggested the new leader’s fatwa would be different. Other MPs have echoed him, and the secretary of the Supreme National Security Council has refused to rule a bomb out.
Some now go further and suggest the threshold may already have been crossed. On the 3rd of November Kamran Ghazanfari, a hardline MP on parliament’s national security committee, said Iran “may have already achieved this capability” and warned that Iran would answer any nuclear threat from the US or Israel in kind. Iran’s top security official insists no change of policy has been approved, and IAEA reports have indicated that Iran does not yet have a viable weapon design. No one outside Iran can confirm the claim either way, and that is precisely the problem: with inspectors gone, ambiguity has itself become part of Tehran’s deterrent.
The case for restraint is weakening. Mohammad Mokhber, a former vice president and now an adviser to the supreme leader, insists control of the Strait of Hormuz is enough of a deterrent, yet closing the strait has not stopped a US naval blockade. Critics warn any dash for a bomb would be detected and struck first, but that fear carries less weight for a country already being struck. Bombed, blockaded and referred to the UN Security Council, Iran has little left to lose by building the weapon it is being punished for. The question in Tehran has shifted from whether a bomb can be discussed in public to whether one should be built.
Change within the region
The likeliest danger is not an Iranian nuclear strike but bolder conduct beneath a nuclear umbrella. Strategists call this the stability-instability paradox: once a state possesses a nuclear deterrent, rivals grow wary of hitting it hard, which allows it to push further with proxies and economic coercion.
Iran is already testing those limits without a nuclear weapon. After the opening strikes Iran closed the Strait of Hormuz, setting off what the International Energy Agency has called “the largest supply disruption in the history of the global oil market” and hit Washington’s Gulf partners, including Saudi Arabia. Then, on the 10th of October a missile fired by Ansarullah, the Iranian backed Yemeni movement widely known as the Houthis, struck Riyadh airport in Saudi Arabia killing 12 people and injuring 309 others. Currently, such moves and support carry the risk of retaliatory strikes from America or Israel. However, with a bomb in reserve, closing the Strait of Hormuz or striking critical Gulf infrastructure would become near impossible to punish, and Iranian officials have already threatened to broaden their targets if the conflict resumes.
The proliferation cascade
An Iranian bomb would be unlikely to remain the region’s only one. Saudi Crown Prince Mohammed bin Salman stated in 2018 that the Kingdom would follow suit as soon as possible if Iran built a nuclear weapon. Riyadh has since signed a mutual defence pact with nuclear-armed Pakistan in 2025 and in July 2026 agreed a civil nuclear deal with Washington that critics have warned could open the door to Saudi nuclear proliferation.
Saudi Arabia would not need years to follow. Unlike Iran, it would not have to build a bomb; it could buy one. The Kingdom already has the means of delivery: Chinese-built DF-3 ballistic missiles, a system originally designed to carry a nuclear warhead, supplemented since 2007 by the more accurate DF-21, which was reportedly modified at US insistence so it could carry only conventional warheads. With Chinese help it has also begun building ballistic missiles of its own. Israeli analysts have long judged that, lacking its own nuclear infrastructure, the Kingdom would prefer to purchase an off-the-shelf nuclear deterrent, and Pakistan is the obvious supplier. In 2013 BBC Newsnight reported a senior NATO official’s claim that nuclear weapons made in Pakistan on behalf of Saudi Arabia were sitting ready for delivery, a report Islamabad dismissed as baseless. Yet days after the 2025 pact was signed, Pakistan’s Defence Minister Khawaja Asif said Pakistan’s capabilities “will be made available” to Saudi Arabia under the agreement. If Iran crosses the threshold, a Saudi bomb could follow in months, not years.
Turkey is the other candidate. In 2019 President Recep Tayyip Erdogan suggested that he doesn’t accept being told Turkey isn’t allowed to possess nuclear warheads when others do. The war has also demonstrated to Gulf states that American bases didn’t stop Iranian missiles from targeting and reaching them. A campaign intended to prevent one new nuclear state may yet create the conditions for several.
A treaty running out of credibility
The global cost may prove the most lasting. Iranian lawmakers are pushing for a fast tracked bill to leave the Non-Proliferation Treaty (NPT). If it passed Iran would become only the second nation ever to do so, after North Korea in 2003, and something Russia, Tehran’s closest major partner, has stated it does not want.
The deeper damage lies in the lesson others would draw from Iran’s experience. Libya and Iraq abandoned their nuclear weapons programmes and were subsequently the targets of military action that toppled their leaders. In comparison North Korea created and kept its weapons and has faced no such military action. Pyongyang has cited the fates of Saddam and Gaddafi as proof that abandoning a nuclear weapons program is potentially disastrous. If Iran reaches the same conclusion, every insecure government watching will learn that the treaty protects only those strong enough not to need it.
