[yongjik]

> what would be your perspective if the U.S. decided that South Korea was no longer worth defending ...

You mean, what if the US decided that keeping an air force base within 1000 km of Beijing isn't worth the cost?

Well, it that case, it sucks, because our national defense budget will likely have to increase a lot. But an independent country cannot outsource its defense to others forever, so South Korea should have contingency plans for such a case, or at least I hope so.

As you said, alliance goes both ways. The military ties to the US did help us tremendously in the past. But the US is not stationing thousands of soldiers out of goodwill: they're doing it because South Korea is located at a really convenient position in America's game of global dominance. I think it's mutually beneficial (for now), but if America decides it isn't, well then that's it.

[fastball]

What does the US get out of having a military presence in South Korea? Sure, we have a base that's closer to our "enemy" than we would if we were just in Japan. But at this point, the US isn't going to win a war with a land army, so even if it was for aggressive military purposes, it wouldn't be nearly as effective as you think it would be.

Hint: maybe we keep military bases in SK to defend South Korean, because over the past 67 years of our alliance, South Korea has become a fantastic trade partner and we want to ensure that such a mutually beneficial relationship continues far into the future.