North Korea is a threat to Seoul. If they wanted to they could do some serious damage there, since the South Korean forces are outnumbered pretty much 2 to 1. The North Korean forces have some very well trained forces, and with the limited land space there is there is no way USA or South Korea will launch any sort of nuclear weapon towards North Korea. They won't risk the winds taking radiation towards China and other nations and pissing them off too. The place where South Korea beats North Korea is obviously in their tech. North Korea has a lot of man power, but not a lot of technological power. But nevertheless, North Korea vs. South Korea would not end up in a very easy victory for either side.
Obviously USA would get involved against North Korea, but don't be too sure that it will be a full fledged war. Even China did not condone North Korea's provocative nuclear tests. I would expect to see some sort of partial intervention first, and try to get China to get North Korea to stop. If that wouldn't work, I wouldn't actually expect China to get involved on North Korea's side, rather remain neutral in the war and allow USA free passage, or maybe even chip in against the North Koreans. North Korea has been well known to capture Chinese citizens, go against China's word etc. Let's not forget: China is pretty much just giving them food. Other than that they aren't really what I'd call "allies". China could be considered being generous to them. China said they don't want war on the Korean island, and they said they will "safeguard peace on the Korean peninsula."
As for the Civil war, well... I don't take Obama's words very seriously when he thinks that everyone will comply when he forces everyone to hand in their assault weapons. Honestly it's not just the fact that it's assault rifles, it's that I think every person in their mind knows that handguns will be next. Deny it all you want, but I can assure you that just as you see on the T.V. right now about the media bad mouthing assault rifles, you will see the exact same thing happen with Handguns. As the assault rifles go, stabbings are going to increase, theft is going to increase, and the government would have accomplished nothing. Spent all this money and the crime rate stayed the same. As Rick Perry would say, "Oops."
We all know that it's going to start with the abomination of assault rifles. Then as more people die from handguns they are going to sign more executive orders banning certain things with handguns. Aka: no more than seven rounds in a magazine (not clip, magazine

) etc.
I would be very upset if the president does anything more against the second amendment right now. Nothing like promising to preserve and protect the constitution and then stomp all over it and infringe on one of the most basic rights of American citizens.
(I know someone is going to bring up the patriot act, and I'll tell you right now that I don't agree with that either. Just because I am a conservative does not mean that I agree with what every president has done in the past. I preach small government and less interventions in people lives. I guess I have some libertarian blood running through me you could say. Regardless of that, it still does not amount to drones, keeping people in jail without due process, and all the broken promises that people fell for and will never get under the president)
So, what do I think the USA is stockpiling for? Both. Because both can happen and at this rate, at least one of them will.