local breakthroughs on the major routes towards Seoul—their first operational objective.Playing devil's advocate: How do we know Seoul is the operational objective? It seems obvious (capital city located near the border) but what if DPRK went for something not so obvious? i.e. "Attack him where he is unprepared, appear where you are not expected" (classic Sun/Mao approach)
Also, what if Pyongyang tries to draw in a sympathetic third party that would also give the US/ROK pause? China is the obvious choice, but there is also Russia ...
An interesting feature of this war is that since both sides look and speak more or less alike, covert insertion and operation is easier for each side—but especially so for North Korean agents who may move freely within South Korea’s open society.
In the 1990s I remember reading an account of North Korean special forces landing by submarine and trying to infiltrate ... and immediately being tripped up by unfamiliarity with modern technology. One of the captured agents had no idea every farmhouse had a phone, and was therefore surprised that the alarm was raised as soon as they were spotted.
There is still a huge technology divide, not to mention social giveaways relating to accents and other behavior. Sure, they can be trained, but it won't make them impervious to detection.