Yes, they threathened to bomb ... you forgot that ?
Their nuclear program is pathetic, their most recent bombs not even exceeding that of the Hiroshima bomb.
The Hiroshima bomb, "Little Boy", was a 15 kt bomb. The most recently developed one in North Korea? 10 kt. Here's a bomb test that graphs how much damage would be done specific to what bomb it is: https://prntscr.com/97fxph
Here's the more recent bombs created by the USA: https://prntscr.com/97fyie
This was the largest tested, not created, H-bomb by the US.
Kim-jong-un claims to have Nuclear weapons, and has threatened USA and other western nations.
Should these threats be taken seriously?
In my opinion the only thing Kim-jong-un can attack is a pudding but what do other people think, is it worth worrying about.
Should we enlist?
Kim, interstingly enough is a very powerful person. Before we ask will he? lets determine if he did. Now the most likely events for North Korea to go to war are #1 with South Korea and #2. Both by the way would involve the united states. But to answer your question of should these threats be taken seriously? YES! Kim is a ticking time bomb and he has nuclear weapons witch is confirmed to be said by the year 2017-2020 they could very easily reach anywhere in the U.S., as well as the fact that if in the near future tensions get to high between north and south korea, the us backs south korea and would interfere with the war. But listen a even larger picture than what this all is if either of these events were to happen, or if north korea essentially attacked any country, it would most likely trigger world war III. Which is scary to think about but you cant change what happens. Now to move on to your question about enlisting, America is the greatest military and economic power of the world, you most defiantly do not have to risk your life, many other already have.
I am just saying... USA has been having training missions with South Korea right next to North Korean's border for years. In no way I am for North Koreans, but if America really wanted peace with them, they wouldn't act in such provocative ways. I don't think its a threat, as long as we don't mess with them, they won't mess with us.