South Korea can easily reach North Korean ports. Take all the markings off a few F-15Ks and let 'em have it.
See that pod under the right intake? That's my little contribution to the effort. Use that, and it would be "bombs away" before the NKs even knew they were there.
It would be an exciting ride though. Coming back might be even more exciting and "interesting".
Course a better result could be obtained by sinking a NK sub, or three. They are noisy, by diesel electric standards anyway, and should not be all that hard to find. Although their mini-subs of the
Sang-O class, which can have 2-4 torpedo tubes are pretty small and probably quite a bit quieter as well. But they can't get far from port, or a mother ship.
Sub sinks, no one sees. Deniability, but the NKs would get the message.