Otherwise known as the We Can Kick North Korea’s Ass in a Day or Two bullshit.
I would not get your hopes up about invading North Korea. I hear their equipment is better than you think and furthermore they have four million many under arms, with many of the rest in citizen militias. The army is well fed and well trained. North Korea has been preparing for an invasion for decades and it seems like half the military infrastructure is underground.
There is a huge arsenal of artillery pointed at South Korea and if we ever attack them for any reason, they will turn those guns on and the first fifty miles south of the DMZ will be pretty much leveled faster than you can blink your eyes. The artillery is not that easy to take out and as most it is actually underground in tunnels in mountains. the artillery actually pops out of the tunnels in the sides of the mountains, fires away and then retreats back into the tunnel while the tunnel closes behind it.
If we do invade with a ground army, I would worry about that too. North Koreans are some of the most brainwashed people on Earth and most of them have a fanatical hatred of the US. I am convinced that much of the army and even a lot of the militia would fight to the death. It would be very, very ugly and we might lose a lot of men. I have seen estimates of up to US 30,000 dead from an invasion of North Korea.
The war might go nuclear pretty fast not because the North Koreans would shoot nukes but more because we might. Contrary to popular MSM lie, North Korea does not have a usable nuclear weapon.