(Bloomberg) -- The escalating conflict between Iran and Israel has refocused the world’s attention on the Islamic Republic’s nuclear ambitions, and whether they’re giving it the capability to fire an atomic weapon.
Iran began ramping up production of fissile material in recent years, after the US pulled out of a deal under which Tehran curtailed its nuclear activities in exchange for sanctions relief. Today, it would likely be able to produce a bomb’s worth of the necessary enriched uranium in less than a week. It would still have to master the process of weaponizing the fuel in order to produce an operable device that’s capable of hitting a remote target.
What has Iran done to gather the makings of a bomb?
Under the landmark 2015 accord, Tehran pledged that for 15 years it would not enrich uranium beyond 3.7% — the concentration of the fissile isotope uranium-235 needed for nuclear power plants. It also promised to limit its enriched-uranium stockpile to 300 kilograms (661 pounds), or about 3% of the amount it held before the deal was struck.
According to inspectors of the International Atomic Energy Agency, Iran was observing the terms of that accord when in 2018 the US withdrew from the deal under then-President Donald Trump. At that point, the curbs on Iran’s atomic enrichment efforts meant it would have needed a year to produce enough fissile material to fuel a nuclear weapon.
Starting a year after the US left the accord and reimposed sanctions — denying Iran the promised economic benefits of the deal — Tehran began to ramp its program back up. It’s accumulated enough enriched uranium to construct several bombs should its leaders choose to purify the heavy metal to the 90% level typically used in weapons. Moreover, it not only returned to enriching to 20% but for the first time progressed to 60%, a level of purity the IAEA says is technically indistinguishable from weapons-grade fuel.
Iran’s engineers are producing the equivalent of about one bomb’s worth of 60%-enriched uranium per quarter, according to IAEA data. That material can be quickly enriched to the 90% levels used in most weapons, to then produce the 15 kilograms of fuel used in a simple warhead.
Why is enrichment so important?
Obtaining the material necessary to induce atomic fission is the most difficult step in the process of making nuclear power or bombs. Countries need to develop an industrial infrastructure to produce uranium-235 isotopes, which comprise less than 1% of the matter in uranium ore but are key to sustaining a fission chain reaction.
Thousands of centrifuges spinning at supersonic speeds are used to separate the material. The IAEA keeps track of gram-level changes in uranium inventories worldwide to ensure it isn’t being diverted for weapons.
Iran has always maintained it was pursuing nuclear energy, not nuclear weapons, but world powers have doubted that claim.
It has built steel-reinforced underground facilities at its two main enrichment sites in Fordow and Natanz, making them harder to target in an airstrike.
What else does Iran need to be capable of launching a nuclear weapon?
In addition to the fissile material, there’s the bomb mechanism and the means of delivering it. It’s likely that Iran already has the technical knowhow to produce a simple gun-assembly implosion device such as the one the US dropped over Hiroshima in 1945. An Iranian pilot would have to survive an incursion into enemy territory to dispatch it. Alternatively, the hardware could conceivably be delivered inside a container shipped over land or packed aboard a ship.
To strike a remote target, Iran needs a warhead that’s made small enough to ride atop one of its ballistic missiles and could survive re-entry into the earth’s atmosphere. Tehran hasn’t conducted tests that would suggest it knows how to make a nuclear warhead.
Iran carried out studies on how to assemble such a device until 2003. According to US intelligence reports, it has probably not resumed those studies. Estimates for how long Iran might need to complete the necessary work range from four months to two years. Its most powerful ballistic missile has an estimated range of as much as 5,000 kilometers (3,100 miles), putting all of Europe within reach.
Could Israel attack Iran’s nuclear facilities?
Israel has long considered the possibility of a nuclear armed Iran to be an existential risk, and sought to curtail its nuclear ambitions by force. It is widely thought to be behind the assassination in Tehran of six Iranian nuclear scientists since 2010, and several attacks on nuclear sites inside Iran.
Israeli officials have implied repeatedly that if Iran were to reach the brink of weapons capability, they would attack its nuclear program using air power. The country tested attack plans during its so-called Chariots of Fire war simulation in 2022.
While Israel successfully destroyed an Iraqi reactor under construction in 1981 and bombed an alleged Syrian nuclear site 2007, the challenges posed by Iran are significantly greater. Its facilities are so numerous that intelligence officials have warned a strike may only delay, not destroy Iran’s ability to piece together the technologies needed to manufacture a nuclear weapon. Moreover, any attack would be complicated because Israel’s most-advanced fighter jets would require aerial refueling in order to strike Iran and return home safely.
IAEA Director General Rafael Grossi said Iran temporarily closed its nuclear facilities as a security measure following its first ever missile attack on Israel, in April. He said he was always concerned about the possibility of an Israeli attack on Iran’s nuclear sites, and called for “extreme restraint.”
--With assistance from Paul Wallace and Ethan Bronner.
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