Seoul, a mega city, is built up virtually right to the DMZ. Folks who have never been there would have to see it to believe it.
The battle would be ugly. But then again, North Korea has no effective air force and there is a fair chance the North Korean army would implode into chaos and disorganization.
I've been waiting for somebody to look at that aspect of it. Particularly their army.
The people of NK have been literally starving to death under this regime. Their economy has completely collapsed. They barely subsist on charity from other countries. And now, even that is starting to dwindle.
Once the fit hit the shan, I wonder how much fight the NK army would actually have in them.
I don't see the NK army maintaining cohesion once 20 miles south of the DMZ. They will see so much comparative wealth, everywhere, amongst everything they are surrounded by, combined with all of the propaganda fed to them since birth will create psychological dissonance individually on a massive scale.
On the other note, when FR was young, so maybe 5 or 7 years ago, there was a story i remember about a US spy satellite launching, and several months later the US military analysts discovered over 100+ more underground mortar installations in NK because of increased satellite picture quality, and they feared there were hundreds more than that not yet discovered.
The S.Koreans should use 50lb. bags of rice as sandbags against the first wave, just for the psychological effect.