SK recovers NK missile test parts all the time to assess the level of technology. They are still using rivets, which haven't been used for missiles since World War II. They aren't even flush rivets, invented by Howard Hughes.  https://www.wired.com/images_blogs/dangerroom/2012/12/AP590482977794.jpg  In 1996, a NK Sang-o spy submarine floundered on the shore of SK. The crew committed suicide rather than be captured. More World War II technology.  http://b-29s-over-korea.com/A-Complete-History-Of-The-North-Korean-Navy/images/Sang-o-Class-N.Korean-Submarine.jpg  NK has launched two 3-stage orbital rockets, the first one with a payload of about 50 lbs and the second with a payload of 440 pounds. Both satellites failed. Going orbital is only 200+ miles straight up. An ICBM needs to travel 7,000 miles and they only have the atomic bomb, WWII vintage, about the size of Fat Man, about 10,000 pounds. They are still using rail cars to transport their atomic bombs. NK can't reach Hawaii.