The position you're taking only really works if you start from "Iran will always work towards having a nuclear bomb, no matter what." And yeah, if that's your starting place, you've figured out where that path ends up. You're never going to be satisfied with anything Iran says because your fundamental premise is that they can't be trusted to not pursue a nuclear bomb.
By walking away from the deal, we gave Iran a clear message: "you might as well pursue a bomb because we are always going to act like you are, no matter what you actually do."
No, it's a position that assumes some people there have an interest in a nuclear bomb, and some suspicion is warranted - which means a safe deal needed to have them some distance away from a bomb.
After all, if they just wanted nuclear power, they could have trivially had it without all this fuss. It was always so much cheaper to buy LEU than endure all these sanctions.
Understanding that Iran is religiously opposed to the creation of nuclear weapons with only the caveat that the fatwa declaring the development, acquisition, and use of nuclear weapons against Islamic law may be rescinded in the event of an existential threat to the republic, it naturally follows that people hold that belief because they intend to present an existential threat to Iran.
Isotope separation by centrifuge as a physical process follows the laws of diminishing returns, getting rid of all the uranium variations save the rare target weight takes more and more time as percent purity increases.
"Just a step away" was more a hard bridge to cross back when third party inspectors were at the enrichment centres and leaving locked and logged "long soak" spectrometer instruments behind. It's hard to enrich to greater levels without leaving a ratio fingerprint behind in the gamma spectrum.
https://en.wikipedia.org/wiki/Nuclear_program_of_Iran#Secret...
"The revelation that Iran had built major nuclear facilities in secret, without required disclosure to the IAEA, ignited an international crisis and raised questions about the program's true aim."
You are aware the deal was entirely dependent on Russia, and the follow-on Biden wanted to sign (but couldn't since Iran wouldn't fully cooperate with IAEA) involved Russia even more heavily? There's no other place that both sides accept can store the enriched Uranium or supply fuel rods to Iran.
>Isotope separation by centrifuge as a physical process follows the laws of diminishing returns
It's the other way around. Going from 3 to 20 percent is much harder than 20 to 60 which is harder than 60 to 90. Going to 99.9999% would be tough, but is unnecessary even for nukes.
>"Just a step away" was more a hard bridge to cross back when third party inspectors were at the enrichment centres
They were allowed to enrich to that level under the deal starting in 2031, inspections would have tested if the enriched material was diverted.
Even if they could be effective at such short notice, it would have taken the US being distracted by some other crisis and being unable to act in the short period between detection and weaponization to lead to a nuke.
