South Korea will never again be able to count on the protection of the US with anything but talk. They should build it and far to the south where it couldn’t quickly and easily be overrun.
It is creating a whole new power balance and scurrying for various actions out here by all the powers affected.
Even if SK can rely on US protection, she should build nukes if NK with China’s backing is building nukes. This puts China on notice that their nuke proliferation strategy just backfired on them. NK is demonstrating to the world that a small country can get its way and prevent super power invasion, well guess what minds in Taiwan are churning. If Taiwan builds nukes, China can never retake it. If Vietnam builds nukes, guess what China’s claims on the South China Seas and Spratley Islands just got complicated.
We’ve had tactical nukes in South Korea for a long long time. Everyone over there knows where they are.