There seems to be a notion that South Korea would not be able to handle a first strike by the North. One should assume that their defense planning assumes that Soul gets flattened in the first couple of hours. The South's army is better equipped, better fed, has the most modern communications capability, has more in the way of oil and food reserves, as well as access to more support from the US, Japan, Australia, etc.
The North has more than a million people in their army. But, how much of that million are more than mere prison guards? How much oil do they have to fuel their Southern advance? How much ammo? A nuke thrown at the South, or at Japan, would reap nuclear retaliation. In addition, as soon as a Northern invasion begins, the US and South Korea would be targeting by air and missles every airbase and missle base in the North (and we know where they are). THe north, like Iraq, would be left with so/so mobile missles that down't have the throw weight or consistency and quality of their fixed systems.
The North can reap havock. THey can kill a million southerners. THey can not sustain the battle. That's their problem. China isn't going to sustain a pre-emptive attack and risk a wider war and the loss of their economic gains. THe Russians aren't going to get involved this time either. The North will be doing this alone. They are dangerous, but they have to win on day one or the lose. And, I don't think they can win on day one, especially if the US and the South are on warning.
This is a lot of talk about nothing....unless they are completely deluded (possible) and than they die.