[RobertoG]

I don't understand how that would happen.

First, North Korea can't force the U.S. to do anything, the only they can hope for is to make an invasion too expensive to consider.

Second, even if the U.S. accept (why would they?) to leave South Korea, then what? Do NK have the capability of invading SK? That would be their end.

[guildwriter]

North Korea doesn't have to force the US. North Korea just has to convince South Korea to sign a peace treaty. From there getting the US to leave is easy.

North Korea doesn't have the capability at present to invade SK. Having nuclear arms makes invasion unlikely and it gives them a seat at the table as a legitimate nuclear power. With that as a position of security, it's not hard to see how NKorea can leverage that into them getting stronger.

Why would the US accept? Can you imagine the political fallout for the President and party in power if they're forced to keep acquiescing to NKorea anyways? Or if they decide to invade NKorea and deal with the aftermath? NKorea doesn't have to launch a missile to present a legitimate threat and project power around the world.

[RobertoG]

It seems to me that we agree that all the issue it's basically about self-protection from external threads.

[guildwriter]

No we don't. Self protection is just a small part of the overall strategy.