US strikes could have halted Iran’s ability to enrich the uranium needed to make a viable nuclear weapon. But that’s not the same as preventing its ability to make a nuclear bomb.
It would be sensible to wait until the dust has settled before judging whether the US strikes on Iran were, in Donald Trump’s, words, “a spectacular military success”. And when dropping bombs that weigh more than 13 tonnes each, there’s going to be a lot of dust, states a Sky News analysis.
If nuclear facilities at Isfahan, Natanz and Fordow were destroyed—as the US claims—or even crippled, it would certainly halt Iran’s ability to enrich the Uranium needed to make a viable nuclear weapon.
But that’s not the same as preventing Iran’s ability to make a nuclear bomb. To do that, they need “weapons-grade” uranium; the necessary metal-shaping, explosives and timing technology needed to trigger nuclear fission in the bomb; and a mechanism for delivering it.
The facilities targeted in the US raid are dedicated to achieving the first objective. Taking naturally occurring uranium ore, which contains around 0.7 per cent uranium 235 — the isotope needed for nuclear fission—and concentrating it. The centrifuges you hear about are the tools needed to enrich U-235 to the 90 per cent purity needed for a compact “implosion”-type warhead that can be delivered by a missile.
And the reality is Iran’s centrifuges have been spinning for a long time.United Nations nuclear inspectors warned in May that Iran had at least 408kg of uranium “enriched” to 60 per cent. Getting to that level represents 90 per cent of the time and effort to get to 90 per cent U-235. And those 400kg would yield enough of that weapons-grade uranium to make nine nuclear weapons, the inspectors concluded.
The second element is something Iran has also been working on for two decades. Precisely shaping uranium metal and making shaped explosive charges to crush it in the right way to achieve “criticality”, the spark for the sub-atomic chain reaction that releases the terrifying energy in a nuclear explosion.
In its recent bombing campaign, Israel is thought to have targeted facilities where Iranian nuclear scientists were doing some of that work.But unlike the industrial processes needed to enrich uranium, these later steps can be carried out in laboratory-sized facilities. Easier to pack up and move, and easier to hide from prying eyes.
Given that it’s understood Iran already moved enriched uranium out of Fordow ahead of the US strike, it’s far from certain that Iran has, in fact, lost its ability to make a bomb.And while the strikes may have delayed the logistics, it’s possible they’ve emboldened a threatened Iran to intensify its warhead-making capability if it does still have one.
Making a more compact implosion-based warhead is not easy. There is debate among experts about how advanced Iran is along that road. But if it felt sufficiently motivated, it does have other, less sophisticated nuclear options.
Even 60 per cent enriched uranium, of which – remember – it has a lot, can be coaxed to criticality in a much larger, cruder nuclear device.This wouldn’t pose as much threat to its enemies, as it would be too heavy to fit on even the best of Iran’s long-range missiles. But it would, nonetheless, elevate Iran to the status of a nuclear power.
The US launched a nuclear program with Iran in 1957. Back then, the Western-friendly monarch—the Shah—ruled Iran and the two countries were still friends. With backing from the US, Iran started developing its nuclear power program in the 1970s. But the US pulled its support when the Shah was overthrown during the Islamic Revolution in 1979, CNN reports in a write-up on the origins of Iran’s nuclear programme.
Since the revolution, which transformed Iran into an Islamic Republic, Western nations have worried the country could use its nuclear program to produce atomic weapons using highly enriched uranium. Iran has maintained that it does not seek to build nuclear weapons. It is a party to the UN’s Nuclear Non-Proliferation Treaty (NPT), under which it has pledged not to develop a bomb.
At the heart of the controversy over Iran’s nuclear program is its enrichment of uranium – a process used to produce fuel for power plants that, at higher levels, can also be used to make a nuclear bomb.
In the early 2000s, international inspectors announced that they had found traces of highly enriched uranium at an Iranian plant in Natanz. Iran temporarily halted enrichment, but resumed it in 2006, insisting it was allowed under its agreement with the UN’s nuclear watchdog, the International Atomic Energy Agency (IAEA).
It prompted years of international sanctions against Iran. After years of negotiations, Iran and six world powers in 2015 agreed to a nuclear deal that limited Iran’s nuclear threat in return for lighter sanctions.
The deal required Iran to keep its uranium enrichment levels at no more than 3.67 per cent, down from near 20 per cent, dramatically reduce its uranium stockpile, and phase out its centrifuges, among other measures. Uranium isn’t bomb-grade until it’s enriched to 90 per cent purity. And nuclear power plants that generate electricity use uranium that is enriched to between 3.5 per cent and 5 per cent.
It’s unclear how close Iran might be to actually building a nuclear bomb, if at all, but it has made significant progress in producing its key ingredient: highly enriched uranium. In recent years, it has sharply reduced the time needed to reach weapons-grade levels – now requiring just about a week to produce enough for one bomb.
In 2018, Trump pulled out of the Iran nuclear deal and initiated new sanctions on the regime to cripple its economy. Tehran in turn said it would stop complying with parts of the agreement, and started increasing uranium enrichment and uranium stockpiles, and using advanced centrifuges. It removed all of the IAEA equipment previously installed for surveillance and monitoring activities.
The Biden administration then kicked off more than a year of indirect negotiations with Iran aimed at reviving the deal, but those broke down in 2022. In 2023, the IAEA said uranium particles enriched to 83.7 per cent purity—close to bomb-grade levels—were found at an Iranian nuclear facility. Its stockpile of uranium enriched up to 60 per cent had also grown to 128.3 kilograms, the highest level then documented.
And last year, the US shortened Iran’s so-called “breakout time” – the amount of time needed to produce enough fissile material for a nuclear weapon – “to one or two weeks.”
An IAEA report sent to member states late last month said Iran’s stock of 60 per cent purity enriched uranium had now grown to 408 kilograms. That is enough, if enriched further, for nine nuclear weapons, according to an IAEA yardstick.
The IAEA has long accused Iran of violating its non-proliferation obligations, but on Thursday – for the first time in almost 20 years – its board passed a resolution officially declaring Iran in breach of those obligations. Iran promised to respond by escalating its nuclear activities.
Enrichment is a process that increases the amount of uranium-235, a special type of uranium used to power nuclear reactors or, in much higher amounts, to make nuclear weapons.Natural uranium is mostly uranium 238 – about 99.3 per cent, which isn’t good for power or bombs. Only about 0.7 per cent is uranium 235, the part needed to release energy.
For nuclear energy use, that tiny amount of useful uranium-235 needs to be concentrated. To do this, uranium is first turned into a gas, then spun at high speeds in machines called centrifuges. These machines help separate uranium-235 from the more common uranium-238. That is what enrichment is.
Uranium used in nuclear power plants is typically enriched to about 3.67 per cent. To make a nuclear bomb, it needs to be enriched to around 90 per cent. Iran has enriched uranium to 60 per cent – not enough for a bomb, but a major step closer to weapons-grade material.
Centrifuges are essential for enriching uranium. The more advanced the centrifuge, the faster and more efficiently it can separate uranium-235 from uranium-238 – shortening the time needed to produce nuclear fuel or, potentially, weapons-grade material. Iran has spent decades improving its centrifuge technology, starting with its first-generation IR-1 model in the late 1980s. Today, it operates thousands of machines, including advanced models like the IR-6 and IR-9.According to the Arms Control Association, Iran’s current centrifuge capacity could allow it to produce enough weapons-grade uranium for a bomb in less than two weeks.
