I don’t think Americans need to worry much about a nuclear North Korea. If it really came to a nuclear exchange, I think the US would simply wipe North Korea off the map, long before the North Koreans had gotten anywhere near the US.
The main threat is what they might do to South Korea or Japan, which are much closer. Personally, at the risk of seeming to propose nuclear proliferation, I think Trump’s suggestion that South Korea and Japan should consider nuclear arms has some sense. The US can’t be everybody’s world cop all the time. Japan in particular could develop nuclear arms very quickly.
The main problem with Trump’s suggestion is that the Chinese wouldn’t like it. They still don’t trust Japan even though World War II ended 71 years ago.
I don’t think its much use asking the Russians to talk to the North Koreans. North Korea is no longer a client state, and hasn’t been for years. The Russians have their own chestnuts in the fire, without bothering about a nation which is no real threat to them.
I sometimes think Australia should have a nuclear option. We ultimately rely on the US for protection when its all said and done, yet we have the world’s largest Moslem nation as our nearest neighbour. And there’s been a significant rise in religious fundamentalism in Indonesia lately, no doubt spurred by the economic inequality and hardship endured by many of her people.
But I can’t see that happening, so it’s merely my opinion.