Here's a bit of advice from The New Republic on how to handle the North Korean situation:

How about withdrawing most of the 37,000 U.S. troops stationed in South Korea?

and...

True, an end to the American presence in South Korea could make it easier for Kim's troops to come storming across the border to fulfill the "Dear Leader's" expansionist aims. As a result, South Koreans will inevitably feel more exposed. But after 50 years of guaranteeing the South's security, surely it'd be difficult for Kim to conclude from the mere act of our leaving that we wouldn't intervene in the event of an attack. And, in any case, the marginally increased threat just might force those blasé South Koreans to take their own security more seriously. An analogous form of ambiguity has been helped bring relative stability to the Taiwan Straits. It may be exactly what our Korea policy needs.

Greene's point is that the South Koreans have basically taken the security and support of America for granted, and that if they don't really like us or want us there, fine...pull out.

Instinctively, this feels like a good thing to do. They don't appreciate us? Screw 'em...let's go home.

But it's never as simple as that. Part of the problem is timing. In hindsight, it would have made more sense to pull most or all of our troops out of South Korea over the past 8 years, after making nonproliferation pacts we thought the North Koreans were abiding by. But what sort of signal would it send if we pulled all 37,000 of our troops out of South Korea right now?

Many believe that Hussein became emboldened enough to invade Kuwait because he honestly thought nobody, not even the U.S. would have the stomach to stand up to him. It was a calculation, and it was wrong. But when we pulled out of Somalia, the thugs were watching.

In over a decade of armed conflict, they've seen overwhelming American military force, mostly from the sky, but there is still the widespread perception that America is squeamish about spilling American blood. That ever since Vietnam, we've lost the will to fight tough fights.

Some of have criticized Operation Anaconda in Afghanistan for relying too heavily on Afghan soldiers, fighting by proxy, and that this policy perhaps allowed bin Laden to escape from Tora Bora. I don't know if that's true or not, but we have definitely become highly sensitized to both American deaths and the deaths of civilians in the countries in which we have to fight. This is generally a good thing, though there are definitely costs. One potential costs is the emboldening of petty dictators.

Which brings us back to North Korea. If we were to pull all of our troops out of South Korea now, in the midst of revelations that North Korea has reneged on its promise not to nuclearize in exchange for huge portions of fuel and food, in the midst of belligerent, histrionic rhetoric from Kim Jong-Il, then exactly how would that play on the world stage?

Gee, I wonder what sorts of things would be said in the North Korean "press". And how would it project in the Middle East? Yet more fuel for those who insist on a double-standard when it comes to the way we're dealing with Iraq and our posture towards North Korea.

So while it sounds like a good idea at first, the notion of pulling all of our troops out of South Korea is fundamentally flawed. I wish we could, but I don't think we can afford to, especially right now.