Yet again, we are seeing the repercussion of not taking the advice of our founders to heart—staying out of foreign entanglements. Though the circumstances of our current status of alliances can be well understood. The catastrophic results of the treaty of Versailles after WWI, was a good indication that someone had to manage events of post WWII. And that someone was the U.S., as we were the only remaining nation that was not devastated by that war. The total makeup of the world would be starkly different today had not the U.S. stood against the onslaught of Communism.
As for the U.S. still being in S. Korea, some old grizzled vets that I knew, firmly believed that the goal is not to keep the north from invading the south but the south from invading the north.
The unfortunate part about our current position in the world, is that it will be virtually impossible to backtrack and leave many of those nations to the fickle vagaries, of populations no longer interested in defending themselves. Its the consequences that our national parks have long understood when visitors are told to not feed the bears.