A rchive Date
[ 02-04-2026 ]
Category
[ International Relations ]
sub-Categoy
[ Iran ]
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[https://www.cbc.ca/news/politics/iran-nuclear-bomb-united-states-war-9.7147664
Iran's nuclear constraints were more diplomatic than technical. Then the bombs started dropping
Nuclear scientists say risk of country building a bomb has only grown
Evan Dyer · CBC News · Posted: Apr 01, 2026 4:00 AM EDT
Nuclear weapons experts are warning that the U.S.-Israeli war on Iran, ostensibly launched to prevent the country from obtaining nuclear weapons, may have instead made an Iranian bomb more likely.
That is because prior to the war, Iran was held back not by technical constraints but diplomatic considerations, say two nuclear weapons experts who were involved in past U.S. efforts to sanction and contain the country.
Those diplomatic calculations have changed.
Outcomes that Iran tried for years to avoid - bombing of its cities, assassination of its senior leadership, the destruction of its air force and navy - have now occurred.
The scientists say that the focus on preventing Iran from enriching uranium to what's often termed "weapons grade" has obscured the fact that Iran does not have to attain the levels of enrichment seen in sophisticated nuclear weapons produced by superpowers in order to make a fearsome bomb.
Physicist Steve Fetter, a member of the U.S. National Academy of Sciences Committee on International Security and Arms Control, says Iran's estimated 440 kilograms of 60 per cent enriched material "is already directly usable to produce nuclear weapons."
Fetter headed the national security and international affairs division of the White House Office of Science under U.S. President Barack Obama and was involved in the nuclear deal signed with Iran - torn up by President Donald Trump in his first term.
'Breakout time' likely short
"You can probably make a weapon - a rather large and crude one - at 60 per cent enrichment," agreed plasma physicist Tara Drozdenko, who has worked on nuclear weapons issues for the U.S. Navy and State Department and served under the administrations of Obama and George W. Bush.
"It's just going to be very bulky and big, because you'd need more uranium to get to a sustained chain reaction."
Drozdenko has extensive experience dealing with proliferation issues. She headed the Country/Regime Sanctions Unit at the U.S. Department of Treasury from 2008 to 2012, where she managed more than 20 of the U.S. government's economic sanctions programs, including on Iran and North Korea.
She also represented the United States on NATO's Senior Group on Proliferation.
Drozdenko says Iran chose to stop its enrichment at 60 per cent for political, rather than technical, reasons.
"They would have and could have continued enriching to higher amounts," she said, if that was their aim.
Most of the effort in uranium enrichment is in the early stages. As more non-fissile material is spun out of uranium in the centrifuge, enrichment becomes faster and easier. Getting from 3.67 per cent to 10 per cent requires far more time and effort than getting from 10 per cent to 90 per cent - considered weapons grade.
With Iran already sitting at 60 per cent, its "breakout time" to get to weapons grade is short, say the experts.
The United States and Israel bombed Iran's nuclear facilities last year - which Trump at the time said left the regime's capacity "obliterated."
Some believe the Iranian enriched uranium stockpile is now buried under rubble.
Fetter concurs that even if airstrikes succeeded in destroying all of Iran's centrifuges, that would likely slow rather than stop progress to higher enrichment, unless the existing nuclear material were also rendered unrecoverable.
"Iran clearly has the expertise to build centrifuges at a small facility, and they would only need a small facility to enrich that material if they have access to it, fully to the weapon grade."
The bomb design Iran would most likely aim for, says Fetter, "is a gun-type device, the type of device the U.S. used on Hiroshima," which is "simple and easily within the range of what Iranian scientists and engineers could do."
That bomb used a conventional-explosive "gun" to blast one block of 80 per cent-enriched Uranium-235 into another, thereby creating the critical mass necessary for a fission explosion.
Few technical barriers
"I don't have any reason to dispute what other experts have said," said Drozdenko, "which is that [the Iranians] were months away [from weapons grade] if that had been their intention. But I think that there's been a lot of evidence that they weren't intending to do that, and that the negotiations were going pretty well."
Israel's Benjamin Netanyahu has been issuing urgent warnings about an Iranian bomb for decades. Meanwhile, Iran's rulers have insisted that Tehran has no interest in a bomb, and its supreme leader even issued a fatwa describing nuclear weapons as haram, or contrary to Islam
.
The truth about Iran's intentions seems to have fallen somewhere in between.
Iran did have a real covert nuclear weapons program, code-named Amad, from 1989 to 2003, according to the International Atomic Energy Agency (IAEA). Iran halted the program but sought to maintain the scientific capital and expertise it had already generated, said Fetter.
The scientists say Iran's program after 2003 appeared to be driven by a desire to create and wield diplomatic leverage, meaning Iran was mainly interested in what it could get for not building a bomb.
Under the Joint Comprehensive Plan of Action (JCPOA), what Iran got was relief from sanctions - until the U.S. pulled out in 2018.
Under the JCPOA, Iran gave up its most enriched uranium, then at 20 per cent, and accepted a 3.67 per cent cap. International Atomic Energy Agency (IAEA) inspectors had access to all Iranian nuclear sites and "that put an effective cap on the possibility that Iran could break out and develop nuclear weapons," Fetter said.
He sees the Iranians "very slowly" enriching uranium in the years since as an attempt to "maintain bargaining leverage."
New calculus
The remaining Iranian leadership need only look to the example of North Korea to see a country with real nuclear weapons, rather than just centrifuges and raw material, that has not been attacked and isn't likely to be.
Figures in the Iranian regime who could have argued that holding back from developing nuclear weapons would prevent attack have been left discredited, or been killed.
"This is what I worry has shifted the equation, the decision calculus inside Iran," said Fetter.
"The U.S. has not been a reliable partner in negotiating with them in the last 10 years," said Drozdenko. "We withdrew from an agreement with them about this, and we started a war with them while they were in negotiations."
Despite the huge expense of developing a bomb, and the likely setbacks they face due to the destruction from the war, Drozdenko said Iranian resolve to attain one may only have hardened.
She added that countries other than Iran were likely also recalibrating their thinking on the cost-benefit ratio of nuclear armament.
Fetter says that, if the Islamic republic survives, he doubts the U.S. would be able to prevent a reactivation of its nuclear program using satellite intelligence and airpower alone.
"I just don't see how that is possible. Iran is a very big country. Lots of well-trained scientists and engineers, lots of possible locations where you could have a small-scale enrichment or conversion facility."
Israel had good human intelligence sources on Iran's nuclear and missile programs, as evidenced by its assassinations and other covert operations in the country. But it's not clear how much of that infrastructure remains.
He said talk of sending U.S. troops deep into Iran to retrieve its uranium is "extremely hazardous" and "unlikely to succeed."
"Unless you can somehow destroy the knowhow, kill all the scientists and engineers, unless you are willing to occupy the country, I don't see how you could eliminate this capability," he said.
"In fact, such missions are more likely to move Iran in the other direction: toward a commitment to rebuild the nuclear program."
Evan Dyer has been a journalist with CBC for 25 years, after an early career as a freelancer in Argentina. He works in the Parliamentary Bureau and can be reached at evan.dyer@cbc.ca.
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