Thwarted said:
Iran, it's no longer a matter of "if", but "when"
Iran had better watch its ass. Seriously, from what I've seen of Iranian technological and other advancements related to their ability to threaten the US and its bigger allies/Israel, apparently the will of Allah isn't enough to overcome missiles through your bedroom window, and, if they decide to use nuclear missiles, we(America) can probably use what missile defense systems we have developed since the Cold War and knock those duct-tape and plastic Iranian birds right out of the sky.
Seriously, though. Iran is getting pretty daring in essentially every gesture and word aimed at America/Israel. The truth is, Iran has little to no real military power against the United States or Israel. I think it goes without saying that our forces would kick Iran's ass, but Israel, some would argue, would be more vulnerable. True, but Iran would be painfully defeated in yet another victorious war for Israel.
On topic: I think, most likely, there will be a war between North and South Korea, beginning another round of combat in the ongoing Korean War (Yes, it is still going on, though the ceasefire has held since 1953). First off, South Korea has a military sufficient to pound North Korea into next week, even with Kimmy-boy's nukes. The real problem would be China. As was mentioned above somewhere, maybe in the OP, China would almost certainly be dragged in in support of the north. I'm not so sure about that. China would likely join if we were really aggressive in the course of the conflict and took no account of Chinese concerns, but if we do things right, China probably won't bother fighting. Neither side is as stupid as people like to think, where the slightest incident will set off a nuclear war. Sure, China has a government based on what used to exist under the communist system, but Mao isn't in charge anymore, and the Cold War has been over for 20 years. China and the US are both huge trading partners, with relations that are somewhat better than people believe, though they are not quite perfect. Anyway, I've also heard from my friend, who is South Korean, meaning from South Korea, not just ethnically Korean, that China and North Korea are pulling apart somewhat on account of Kim Jog Il's rowdy behavior. N. Korea is no longer as much in line behind China as it once was, so, while China would probably support North Korea over the US, the Chinese would not send in the cavalry to save the north unless we send in another MacArthur and really give them a reason to be defensive.