North Korean can't keep up their rhetoric forever lest the Chinese get fully fed up and do something that matters to harm North Korea. So the North Koreans need to wrap up this production of Dead South Koreans Theater.
Apparently, the South Koreans have lost track of two North Korean mini-subs that put to sea:
South Korea has lost track of two North Korean mini-subs that were seen to leave a base on the west coast, just north of the DMZ several days ago. These 130 ton subs can only stay at sea for a few days, or a week at most.
They'd have to reappear in a port or strike pretty soon, then.
This could be the part that Pyongyang loves the best.