There is no crisis in North Korea. This piece is fake reporting. 

There is continuation of the Korean War in the form of preparation and threats. But this have been the situation since 1954 when an armistice was signed. An armistice is just a stop-shoot agreement. The war continues, no peace. Note the U.S. also invaded China. 

What's the big issue? The Koreans want unification of their country, just like Germany. Who's stopping it? The U.S.A. (Surprise!) But why? The U.S. want to maintain its military forces in Korea, along with that in Japan, to stick it to China. (It's a very massive force: 100,000 troops, entire naval fleets, complete with strategic nuclear weapons.) It's part of its global empire. U.S. have never withdraw its forces from foreign land peacefully - it requires a defeat in war. 

North Korea, supported by China and Russia, says any unification of Korea require no foreign forces in the land. This the U.S. will not agree. 

So both sides continue to prepare.