[Jack Hydrazine]

Sounds like the S. Koreans need ASROC.
http://en.wikipedia.org/wiki/RUR-5_ASROC
https://www.youtube.com/watch?v=hRqjTKzS1JU

[doorgunner69]

I suppose the question might be, like the Japanese, do they have the components of a nuke variant on the shelf ready to assemble if needed?

Both countries have the technical expertise and the tactical need if push comes to shove, while having plausible deniability.