The truth is, of course, that if Kim pushes a button, it's far more likely that North Korea (or at least its launch facility) will be the site smoldering. North Korea doesn't exactly have a lengthy track record of successful launches of anything. Their long range missiles are more likely to blow up (or fizzle out) on the launch pad than they are to make it off the ground, and when the missiles do launch successfully, they don't seem to go where they were supposedly aimed. If North Korea decides to bomb Seoul, odds are they'll accidentally nuke Pyongyang instead.
As for North Korea posing a threat to the United States, pshaw. There's been a lot of blathering about a North Korean missile hitting the west coast, but when you listen closer, it turns out the "west coast" is actually western Alaska. As in the Aleutians. Somehow I find it hard to believe the North Korean military would waste one of its handful of warheads by trying to bomb Tanadak or Ugidak Island. Wiping out a seal colony wouldn't seem to have much propaganda or tactical value. Besides, the North Koreans, isolated and nuts though they may appear, are aware that for every nuclear weapon they have, the U.S. has 3,000 or more. They know that if they were stupid enough to ever use a nuke, they'd be utterly annihilated in less than an hour. The posturing and threats are bizarre, but they're not real. They're theater designed to help keep the Kim family in power
Still, I can understand why the Japanese and South Koreans would be nervous. There's always the possibility that the ongoing puppet show that's designed to make Kim Jung Un appear as militaristic and