> Are you being intentionally dense? Why wouldn't they be building it in their own territory if nobody was stopping them?

They actually could. This has been an ongoing discussion in South Korean politics for years. Nuclear Submarine shipbuilding is a large undertaking and it requires a lot of security to prevent sabotage in ways that other types of shipbuilding just don't have to put up with. So it is in many ways cheaper and more secure to just rely on the US for nuclear shipbuilding as we already have the infrastructure and we are on the opposite side of the world from any adversaries who would have interest in sabotage.

> Besides, I already replied to your other comment that South korea is not allowed to enrich uranium by the US.

This is not true. There are mutual agreements that set the limits on enriched uranium for military purposes but they are flexible agreements that can be renegotiated or broken off as needed. The US has them with everyone including our allies and our adversaries. It's essentially just a tool to say "hey you need to discuss this publicly within your country first before you can change it". Nothing more or less.

> Why wouldn't they be building it in their own territory if nobody was stopping them?

Because they don't have the facilities to build a nuclear sub, and America does, since America has built over 200+ nuclear submarines in the past?

Building a nuclear sub, and fueling it, are two separate things.

No, I am not being dense. From your continued lack of citations I am starting to assume there is no law stopping the RoK from enriching uranium (though I have been trying to find one). Uranium enrichment facilities are expensive. If you have a partner nation who is willing to sell you the enriched uranium that just makes sense. Again, it being the property of another nation, they have the right to judge who should have access it it and what they might do with it. If RoK wanted to spend a percentage of their GDP on enrichment facilities they could. They don't have an urgent reason to. Further they don't have any deposits of any uranium to begin with so they would still need to partner with another nation anyways, so I ask you - Why would RoK want their own enrichment facilities?