There's good reason why they looked "indecisive and weak" right after it happened. They were clueless as to how a sub could have gotten into the middle of their training exercise without being detected...
It took a 4-man team (that included my son) brought to SK to review the electronic systems of the planes flying patrol to find the specific problems that had been blinding the SK's for a lengthy period of time.
All of the problems were eliminated and both airborne and ground-based systems have been upgraded to state-of-the-art levels.
The SK's really are hoping the NK's try for a repeat.
I have a son-in-law, CPO, career navy into sub fire control and he is into these things all the time. He's a squadron level now.
Thanks spetz for the note on my tagline...I've fixed it with this post.
South Korea cannot let the North continue such blatant infringements and acts of war. The artillery is a problem, but by using MLRS (if they had enough of them...and they would need a lot) they could nock out a lot of them. They should have all of that prepared before-hand, each MLRS carring it's eight missiles designed specifically for this type of thing, and have several battalions of them and then execute their response against the NKOR Navy.
At the first hint of any use of that artillery, they unleash barrages of MLRS at the artillery positions which are fairly well known.
I hope it never comes to that, but if they do not do something in response, the N Koreans will just keep upping the anty.