So what is the big deal about launching a weather satellite? Well it turns out you need very similar rockets to deliver warheads as you do for satellite launches. What was the main problem the North Koreans had? No Nazis. At the end of WWII the USA and USSR were racing to capture as many Nazi rocket scientists as they could. These scientists jump started both superpowers space programmes. Unsurprisingly a majority of the rocket scientists preferred to defect to the US, it wasn't just over remuneration and work life balance, it was also the whole being Nazi SS officers and whole Lebensraum thing. America having done its own 'Manifest Destiny' a century earlier and having not recently been invaded was more understanding, but I digress.
Before you bag the North Koreans out too much, remember they are doing all this under sanctions on a shoe-string budget, and it's not like the Americans didn't have any problems with their fledgling programme, from xkcd:
Wernher von Braun - a former colonel in the SS - was pivotal in the development of the V2 rocket which bombarded England. The same man took the Americans to the moon, from Tom Lehrer:
"Once the rockets are up, who cares where they come down? That's not my department" says Wernher von Braun.