These folks look like they might be getting dangerous to their neighbours.
However, the likelihood that the (North)Koreans could actually defeat the (South)Koreans in any war that they started is extremely low. The DPRK would be lacking logistical support from ANY country and would have to depend solely on whatever gear/supplies it started out the war with and that means that it would eventually run out of everything - right down to cleaning rags.
If the POLITICAL leadership of the DPRK doesn't understand that fact, the military leadership of the DPRK is well aware of it - which could mean that the "war" ends with a single round of gunfire (in someone's office).