North Korea might really be serious about developing nuclear missiles after announcing the detonation of their third weapon. Seismologists confirmed the test. Supposedly, the device was physically smaller than the previous weapons, but the same yield.
The danger now, in conjunction with their missile program, is that the DPRK will achieve a nuclear ICBM and destabilize the entire region.
The only measures now that are likely to stop them are cooperation from China and inspections of North Korean maritime trade. Neither is likely to happen.