I choose S6’s Question

The most telling aspect of KMAG was its placement under the State Department as opposed to the Department of the Defense. The JCS in1947 viewed the Korean problem as political in nature, not military, and thus the troops stationed there were never intended to win a major ground conflict. KMAG was a demonstration to the international community that the United States was committed to steering fledgling democracies around the red threat; however, this commitment proved to be a façade, at least initially. A global policy of containment requires massive manpower and materiel and because the US did not perceive a war in Korea as realistic, it was able to buy cheap political capital through fielding of KMAG instead of a conventional defense force. KMAG was an illusory and political stopgap to a problem American policy-makers deemed would never escalate to actual war. There’s a reason senior Army Officers cringed at the prospect of a posting to this maligned advisory group.

The relationship between ROKA and US forces today has evolved. The presence of a US Defense force in South Korea provides a metaphorical “red line” in the case of North Korean aggression. I do not believe that the American forces pre-positioned in South Korea are intended to turn the tide of a ground war, but instead to incur the casualties necessary to provide American politicians with the ironclad casus belli necessary to initiate a general invasion of the North. if the DPRK attacks, it will do so knowing the full fury of American firepower will be entirely committed to its destruction. And, as an added bonus, this time we are SURE they have nuclear weapons.