I mean they've sent so many threats that no one actually believes them. A sure Jan tea. I'm sure at this point not even S.K care. Besides it's not as if S.K aren't prepared themselves.
But hopefully this is just as empty as their other threats, because eventually after crying wolf so many times eventually the wolf does actually emerge.
They're only still there because Russia and China allow them to be but the minute they open fire even they won't stand by anymore and it will be bye-bye NK.