My biggest concern with their uranium stockpiles is the true percentage and overall amount. They have only admitted to having 20% because they've been caught with evidence of material enriched beyond 5%. They attempted (lamely) to explain this away by claiming it was for "research and medicine."
So the question seems to be: How long have they had material at 20% and how much do they have? Seems like they've been there for years and probably have enough material for a few weapons.....just my opinion.
I somewhat disagree with your assessment they may have the material, but cannot make it into a deliverable weapon. According to many sources, including the NYT reporter James Risen, the Iranians were able to score a major engineering coup during Operaion Merlin. In that particular CIA op under Clinton, we provided the Iranians with the plans for a W-87 or -88 style warhead.
A former Soviet nuclear scientist was supposed to be their contact and give them plans for a weapon with purposely flawed information. The idea was they would not have the technical expertise to figure it out. Problem was, the operative betrayed us and gave them a blueprint AND appropriate corrections.
Processing the material for it and constructing the weapon with the proper precision and tolerances would seem to be the only missing pieces. I am not sure they need an Oppenheimer or AQ Khan type equivalent for that.
Up to 20% anyone can call it fuel for research, perfectly legal.
Of course we know they are lying and stalling as you said. We have offered to sell them 20% for their legitimate medical uses and they have not taken us up. Could it be that the fuel we sell them couldn't be used for weapons?. Buying it would be far cheaper than making it, so we know what they're up to.
I'm confidant that's all the 20% they have, we have ways of monitoring them that would show if otherwise.
Bottom line they have enough for a bomb and will produce more and more, one bomb or a dozen, they join the countries with nukes and all the glory and honor that brings (sarcasm).
I never said they couldn't make a weapon, I said using uranium for fuel makes that very hard. That's because uranium weapons require a casing of rare earth metals to create "reflectors" that greatly affect the blast yield. They have little of that and are embargoed. Even if they have it, the weapon would be far too heavy for any missile they have or aircraft. They would have to deliver by boat or train, that would be clumsy.
They are many years away, if ever, from delivery. If they had chosen plutonium like Pakistan, it would be another story.
Iran will create enough ruckus just by lighting off a test weapon. Iran knows there would be hell to pay when they do and their political leadership is deeply divided over that. The Saudis and Israel and Iraq would join forces if Iran did so and Iran knows they would be pariahs among muslims and not gain the religious supremacy they are desperate for.