I think this delightful little animation sums it up better than I ever could;
http://www.funnyjunk.com/pages/world.htm.
But seriously, this is likely going to cause Japan to soil its fundoshi and sucessfully allow themselves to have a real army and develop nukes, as has been highlighted on the news, and China is likely going to sit on the sideline for a while, and grudgingly help America if it attacks North Korea. And the US likely will get involved, first through bombing, then through missiles, then through sea, and finally through land. The UK will likely support them, as will Australia. The rest of Europe would probably refuse to get involved, save perhaps Putin. And South Korea sure as hell is gonna bomb the crap out of Pyongyang if the Americans don't do it first.
Oh, and lastly, Kim is probably nutso enough to launch a nuke to a major South Korean city like Seoul or Ulsan. And if that happens, South Korea might nuke them back. And after that, all hell breaks loose.