From what I understand, your basic nuclear weapon (WWII tech) isn’t technically difficult to build because the principles are well known. The uranium is the difficult part.

Sure you could extract the fuel rods, but how many weapons will you get out of it? Is having a handful of low yield bombs worth the international sanctions?

I think you’re better off having strategic strike capability with cruise missiles from submarines. They are a lot more flexible and you can have a lot of them without the other nations getting too upset.

These submarines have 95% enrichment fuel. You only need ~10kg to make a high yield weapon with the right design.

You're going to get multiple weapons with the fuel stored in a single submarine.

Cruise missiles are vulnerable. They can be intercepted and shot down, and they give your position away. Low reward, high risk. Nuclear deterrence can certainly be worth it.

I doubt they will use 95% uranium. [This guy](https://theconversation.com/how-do-nuclear-powered-submarine...) says it is about 50%. Still that is the level Iran is being sanctioned at.

The US uses 93-97% uranium as a matter of public record.

Other countries use more weakly enriched uranium, the US and UK are the exception, so I understand the error in the article above.

See this better source ; https://fas.org/blogs/secrecy/2019/06/naval-reactors-leu/

I wasn't questioning your numbers but thanks for the reference. I think they are being purposedly vague about this. Transferring weapons grade uranium would be a real threat to the NPT.

Well, it's pretty clear, the US is going to provide weapons grade uranium to Australia. Yes it's highly sensitive under the NPT, but the US doesn't care at all.

If the uranium had lower enrichment, it wouldn't be able to last 25 years, so it's certain that this is weapons grade.

Pretty much, yes. Enrichment is the hard part and US subs have fuel enriched enough for a gun type nuke.

I wonder if the subs have enough quantity of fuel to make a respectable explosion. Like if they need to ditch 8 subs to make a bomb, it is pretty low risk if I were China.

If you run the number, you'll find that a sub is going to have at least a half a ton of highly enriched uranium, perhaps even more than a ton.

You wouldn't even need to ditch a single sub to make multiple warheads, certainly not if you use an implosion design as any country can pretty easily do nowadays.