The photos of the facilities are literally all over the internet. The IAEA knew about it and knew Iran was enriching weapons grade uranium. This isn't Iraq 2.
Edit: If you mean "Verification and monitoring in the Islamic Republic of Iran in light of United Nations Security Council resolution 2231 (2015)" [1], that report explicitly mentions up to 60% which is not weapons grade.
[0]: https://www.newsweek.com/tulsi-gabbard-iran-nuclear-weapon-2... [1]: https://www.iaea.org/sites/default/files/25/06/gov2025-24.pd...
It turns out there's a big gap between most peaceful purposes and weapons grade, and this was in that gap.
> Uranium with enrichments ranging from 40% to 80% U-235 has been used in large amounts in U.S. thermonuclear weapons as a yield-boosting jacketing material for the secondary fusion stage
Source: http://nuclearweaponarchive.org/Nwfaq/Nfaq6.html#nfaq6.2
edit: phrasing. it feels like we're going around in circles nitpicking based on a poor framing and the tendency for innuendo on this topic
Also, you can use 60% enriched uranium in the primary stage at the cost of a much larger, less efficient, and dirty device.
All modern nukes are two stage designs, Iran would be insane not to have a fusion stage. It would basically be a Hiroshima style dirty bomb with just 1.5% fissible mass actually fissioned.
Hiroshima was pretty terrible as it was. And I thought the capability that everyone focuses on because it gets nations a seat at the nuclear table was just basic fission weapons. But please correct me if I am wrong.
The bottleneck is UF₆ centrifuges, not the modeling. They're definitely aiming for a fission-fusion design: "The sources note that Iran has attempted to produce deuterium-tritium gas on its own inside Iran - with the help of Russian scientists - but has so far been unable to do so, and due to pressures by the Iranian leadership to accelerate the weapons production program, decided to try to purchase this substance abroad." [0]
India and Pakistan did their first tests ~30 years ago, a lot has changed since then and if you're building a nuke in '25 might as well spend some cash on a simulation cluster and buy some multiphysics simulation software from Russia..
[0] The sources note that Iran has attempted to produce deuterium-tritium gas on its own inside Iran - with the help of Russian scientists - but has so far been unable to do so, and due to pressures by the Iranian leadership to accelerate the weapons production program, decided to try to purchase this substance abroad.
Maybe I'm just putting too much weight on the trials and tribulations of developing the first fusion bombs, and the details of solving or working around those problems is widely known in the right circles these days? Plus advancements in simulation accuracy?
Yes, 60% enriched Uranium is not weapons-grade, but it can be made weapons grade very quickly. Once you've gotten to 60%, you've done 99% of the work - U-235 starts as such a small percentage of natural Uranium that most of the process is spent at very low concentrations.
It can simultaneously be true that Iran isn't "imminently creating a bomb" and also that they're actively working towards a breakout point where they could build a dozen bombs in very quick succession once they did decide to go forwards with the process.
I don't personally think they were rushing towards a bomb at this moment, but Israel isn't really in the mood to wait around until they decide to do so.
Do you have a citation for this?
60% is just a stepping stone towards 90%.
To get 1kg of U-235 requires 1.11kg at 90% purity, 1.67kg at 60% purity, and 140.6kg at natural 0.711% purity.
Was what Iran doing illegal?
Because this is what underlies all of this -- is the premise that Iran is behaving in an unacceptable and illegal fashion and therefore a legal response with violence is justified.
This all presupposes that Iran is breaking the law with their production of nuclear weapons. Are they breaking the law with their production of nuclear weapons?
Was Iran's activities funding militias in Lebanon, Syria, Iraq and Yemen, which launched attacks against Israel and US forces "legal"? Which of the US' activities were "legal"? It's all mostly a bad joke.
However Iran has the stated intention of destroying the state of Israel, and actively incites it's proxies to attack Israel, and this could be seen as a valid justification for taking action. Not a lawyer though.
Is the US funding of Ukrainian militias "legal"?
Not that we would or should but the US could attack any number of countries today and only if one or more countries stopped the US would the victor be able to say it’s illegal.
Geopolitics operates in an explicitly anarchic arena.
Besides, there is no non-military need for enriching uranium beyond a few percent, so it's very clear what those 60% mean.
Has the Iranian government ever explained why they are enriching uranium?
Say you have 10 ton of 2.5% enriched uranium to safeguard. If you turn it to 60% HEU, now you have only ~400kg of fuel to safeguard against air raids. Density of uranium is ~19 ton/m³, so that would correspond to just 21 liters of HEU, one bucket worth, what would make it very easy to transport and hide. That would make it possible to split it and store in safe locations, for example, inside some deep boreholes, far apart to each other, making it impervious to attack, for the duration of hostilities. Once they pass, it can be recovered and diluted back to 2.5% with natural uranium, reconstituting your original 10-ton fuel amount.