That Delft is assuming three things, One the North Koreans could self destruct there missile systems.
these are not American or Russian or European or Even Chinese missiles. Its highly possible that the missile is incapable of being fail safed. Remember in order to engage a safety system on any weapon contact has to be made. The North Koreans lack permanent Satellites, there missile is flying beyond there boarders the North Korean Navy is highly limited in operational capacity consisting mostly of brown water and migit subs. This means that the very ability to track and receive telemetry is questionable. Line of sight radio Delft. Beyond a few miles you need repeaters the North Koreans lack those. And every previous North Korean test missile was recovered by the Japanese or US or even South Koreans.
Two that the North Koreans would fail safe. They have shown little interest in human life, have launched these tests despite protests from the US, SK, Japan and PRC. And have intentional fired artillery shells at populations and outside of her designated boarders before and quite often.
three That the test is cover for another agenda. We all know the distain better China and Japan but its nothing compared to the pure undefined hatred of North Korea against Japan. North Korean movies and television is limited and strictly controlled usual consisting of movies about the Dear Leader, The great Leader and the Divine Leader but there is one exception movies against Japan. North Korea turns anti Japanese sentiments into a virtual religion. If a North Korean missile were to "Accidently" go off course and hit a population of Japanese, its likely they would consider it retribution for past crimes.
No Delft this is a Rouge Regime and although, you may think any counter steps by the Japanese is paranoia or Militancy. I assure you that with the unpredictable nature of NK, and with the Pacific rim's current tensions as well as the news cycle pointed to Europe the situation is ripe for a North Korea provocation. All the signs are there including the addition of now three north Korean drones.