What military equipment does the US make that : - SK actually wants - The US is willing to sell to them - they can't procure from other places or make thems

What military equipment does the US make that : - SK actually wants - The US is willing to sell to them - they can't procure from other places or make themselves? My understanding is the only things that fall into these categories are high-end missile interceptors and jet engines, with large efforts being underway to rectify these issues.