To figure a way out of the problem of neither China on the one side and South Korea, Japan, and America on the other accepting the other side's forces too close to them should North Korea collapse, I wondered if North Korea could be partitioned.
What if all of Korea could be neutralized? Noting the neutralization of Austria after Western and Soviet forces left early in the Cold War, Strategypage says that South Korea broached the concept with the Chinese:
A similar deal is apparently attractive to the Chinese or at least they are willing to quietly talk about it. South Korea is a major trading partner and any deal that solved the North Korean mess and got U.S. troops out of Korea appeals to many Chinese.
As long as a neutral united Korea has the military to keep the Chinese out, that could be a good idea. Our Army brigade in South Korea is tied to that location and was never involved in the troop rotations for Iraq and Afghanistan even when the troops were most stressed. Perhaps the unit could base back to the United States with a set of the unit's equipment kept afloat in Japanese ports just in case.
I'd also want the Japanese and South Koreans to settle all outstanding territorial disputes first. We wouldn't want a nationalistic Korea leaning on China for support against the US-backed Japan over some tiny islands.
But honestly, this idea has merit at first glance. We'd lose an ally. But that ally was fully committed to facing an enemy that we'd also lose--an enemy getting nuclear weapons. We'd lose a defense burden with forces freed up for other contingencies in the Pacific. And as long as Korea actually stayed neutral and was capable of defending that neutrality, Japan would not face a hostile power across the Sea of Japan.
Perhaps the neutralization agreement could encompass force quality limitations close to China's border (like limited heavy armor). If China is also comforted by not having a country or army on their border that they fear would invade them, I won't complain about that either.
I could be missing something, but I wouldn't be upset. Well, we're missing the small event of a North Korean collapse, of course. But other than that, I mean.
A free Korea would still be our friend and trading partner. What's the downside?