Is North Korea a credible threat or are they blowing smoke?

No THREAT should be treated IDLE! We never thought 9/11 would be Possible! Correct?

In my opinion, their leadership is continuing to rattle sabers, not for us, but to convince their own people they are relevant. They have done this over the decades. I was assigned to the UN Command/Korea during the first Gulf war. As I watched the allies take on Iraq, the North Koreans were very careful not to show any aggressive moves (they had much fewer intelligence indicators move than even a normal day). I suspect they did not want to be next in line for the allies.

That said, they need close monitoring since they are a wild card. I think they would prefer to keep the status quo as opposed to starting a war they will surely not win, and really become non-relevant (or non-existent). Just my humble opinion.

North Korea is a very credible threat to South Korea, Japan and all nations that interests in the Sea of Japan and the northern South China Sea PFC Alexander Oliveira. The nation and its military service members have their backs against a wall and most realize that. They have used agents, midget submarines, and other assets to main, kill and destroy in South Korea for decades. their missiles threaten our assets and our allies in Japan, Okinawa, North Korea and the Philippines.
China has been able to reign them in at times but they can play China and Russia against each other since they are within range of Russia sensitive areas in eastern Russia.