I said it in 2008. Obama will end up nuclearizing South Korea and Japan.
Why “a” nuclear submarine? For the same time and money invested, you could build two or more diesel-electric subs. The necessity or surfacing to recharge seems a silly rationalization for the choice. It doesn’t require inter-ocean capabilities to contain North Korea.
I think the South Koreans are threatening to deploy a nuclear sub because it sounds scariest. IOW, this is all smoke and mirrors. SK has no intention of carrying through.
Of course, snorkelers in Hawaii can hear a Nork sub as soon as she pulls away from the pier. They are simply targets, nothing more.