It's one thing to like or dislike the DPRK regime, it's another thing to parrot Western propaganda against their military capabilities. Besides, it is South Korea (with a population about 2 times greater, and an economy at least 5 times greater) that houses foreign troops on its soil, not North Korea. Both North and South Korea are heavily armed and well equipped in conventional terms. Mountainous terrains, deep entrenched tunnels, special forces, bio-chem-nuclear weaponry, a lot of things go in favour of North Korea, while more "modern" aircrafts purchased from USA, and some modern armour developed by South Korea may prove to be of limited use in a long, drawn out conventional war. I do not know if South Korea possess any non conventional weapons, excuse me for my ignorance on that aspect.
In real war, as it happened during the 'last round', foreign 'parties' like China, USA and possibly others are likely to intervene, and then calculations have to be changed to incorporate those external factors.