They aren't nuking them, but they do have occasional military drills and missile launches pointed in those countries' directions.

The Kaesong Industrial Region features South Korean workers commuting into North Korea for work, so it shows that they're not even really isolated from them.

If NK couldn't sustain a crack back from nuking its neighbors, neither could Iran, neither could anyone really--mutually assured destruction and all-- so the point is moot.

And again their isolation hasn't really "worked" for them given their situation with problems like poverty and starvation. Now, no one is really gonna work with them while they insist on some of their craziness, which has probably kept them from really going over the deep end, but that doesn't mean their isolation has been working to improve them as a state. And who knows, if they stopped being so crazy, maybe other nations would be willing to bring them into the fold.

From what I gather, that's kind of the idea behind these negotiations with Iran. Release the stranglehold of sanctions in exchange for very close inspection of any work they do with nuclear power. Hold them to non-proliferation agreements while letting them develop and, hopefully, temper down for some peace in the area. And if it starts to look like they're cheating, starve them out with sanctions like none they've ever experienced.

All really beside the point. A better solution hasn't been posed by anyone that I'm aware of. Doing nothing isn't a solution, more sanctions has been thrown around, but it doesn't really encourage cooperation... The belief of some of the world's more powerful heads of state/government is that these negotiations might be the right path to pursue. Whether it is or not, is to be seen, but the action of these 47 senators is detestable, and I'm sure will have sunk the hope that might have been there based on the statement from Iran today.