There is a huge difference between Chernobyl and a "limited" nuclear war or even a simple nuclear strike. The difference is between tons of nuclear material at Chernobyl to pounds (kilos) of nuclear material in a modern nuclear weapon. The material at Chernobyl was not consumed by the meltdown but in a weapon much of it is consumed to create the kinetic explosion. A nuclear strike is "cleaner" than a melt down by far. Look at Hiroshima and Nagasaki where is a better illustration than Chernobyl. They are thriving cities WITHOUT any significant increases in cancer or other diseases associated with long term exposure of radiation. As for North Korea and the economy...North Korea has no part in the world economy to speak of. In fact, after the communist government were blown off the planet I am sure that a unified Korea would kick their economy into the best they have seen in half a century.
For the rest of you; think outside the box. A bomber dropping a bomb? Think a privately owned aircraft that could carry a few thousand pounds. Don't worry about the return flight, there will be none. Think about a fishing boat or an RV. Like I said the more modes that are changed the more likely that we catch on. By far the easiest way is by boat but don't think that we are not monitoring every boat that comes out of North Korea.