[05]

> I thought a second fusion stage required modeling and testing well beyond basic development

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.

[mindslight]

Aren't there some R&D difficulties there? Like that whole fogbank thing the US forgot how to make? I hear trying to obtain deuterium and I figure it's for development and small-scale experiments, rather than an ingredient for a straightforward bomb recipe.

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?