In a conventional war NK would probably inflict a lot of damage on SK, initially. The rest would play out like Desert Storm. The USA would quickly control the skies. Why? Because one USA carrier has almost as many fighter jets as there are in NK whole Air Force. The USA has the most advanced jets and munitions attached to those jets. American fighter pilots are also better trained. Once the USA controls the sky they could bomb NK at will. NK biggest Achilles heel is that they don't have any oil and couldn't conduct a sustained war. The other problem NK would have in a sustained war is their military equipment is soviet Cold War stuff and doubt they could get replacement parts as needed. If NK went nuclear the USA would retaliate with the same and considering one US nuclear sub has 10 times the number as NK it would be the end pretty quickly for chubby Kim.

China and Russia would never come to the aid of NK. Why? Russia and China have no economic interest in NK. The N Koreans leech off of china and that's about it. China has far more interest in keeping a good relationship with the USA then any benefit siding with NK would have.

It kind of saddens me that people from other countries are so anti American. Must be nice to be the backseat driver. Criticize all u want, but there hasn't a major war in over sixty years and we've done a pretty good job limiting nuclear proliferation. Chubby Kim is a good example of why u don't want nuclear proliferation, NK uses it to blackmail and threaten the world.