What are you talking about? South Korea has one of the most powerful ground forces in the world. They have a fairly well equipped army of some 500,000 men, with reserves of another 3-million. To put that in perspective, the US Army has 560,000 men, and reserves of another 560,000. Keep in mind, South Korea has only 1/6th the population of the US. In terms of military expenditures as a percentage of GDP, they’re the fourth largest military budgeted nation on Earth. South Korea is not some unmilitarized country by any reasonable measure.
Sounds as if you know SK’s status pretty well.
Why are we there ?