Just more pointless fear mongering from North Korea. They are not a big threat at this point in time. It's just empty bluster. Something they have been doing for a long time. If we wanted to, we could blow them off the map at any moment. I just feel incredibly bad for the people of North Korea. I've watched a couple of documentaries on the country, and it's a really bizarre country. I would recommend you search Youtube for them. It's very interesting and depressing at the same time.
This would probably be the greatest mistake of his young career. The America military would completely wipe his army out in less than a month. Their much better train and they have much more expensive equipment and power. Just the Air Force alone would completely destroy the majority of this country it's tiny.
It's not even fear mongering really at this point. It's good old fashioned sabre-rattling. You can always trust that North Korea will continually threaten the US and its allies periodically. It's like clockwork. They need to do this in order to maintain the level of tension to keep their people in line and to keep the people from around the world to be looking at them constantly. It's also done so that they can showcase their power; much like an army goosestep through the streets, but for the international audience.
Sabre rattling is done by everybody. The US constantly has military exercise near or around their enemies' territories, Russia often habitually trespasses into UK airspace to test their response times, and so on.