Why are we still in Korea?

Why are we still in Korea?

" Unlike 1950, South Korea is not an impoverished ex-colony of Japan. She is the largest of all the "Asian tigers," a nation with twice the population and 40 times the economy of the North.
Seoul just hosted the G-20. And there is no Maoist China or Stalinist Soviet Union equipping Pyongyang's armies. The planes, guns, tanks and ships of the South are far superior in quality.
Why, then, are we still in South Korea? Why is this quarrel our quarrel? "