
Originally Posted by
Ksyr
Supplies have to be shipped from USA to Korea with convoys.
First check your minimap. There is a tab for supply. Make sure there are red arrows to all ports in Korea. Unless you have changed anything in the production=>convoys menu convoys should be created automatically.
Next check on the production page that you have enough available convoys. Playing as the US I always have to make more than what I start with.
Third, take a look at your forces in Korea. A common mistake is to have too many troops so you can't supply them even if all ports are at maximum. Armor and mechanized infantry require a lot of supplies and as USA it is tempting to build them because of the low manpower and high IC.
Have you researched the supply techs in the theory tab and the naval basing in naval tab? They are on my list of "must have" techs.
In this situation you could possibly use transport aircraft to run air supply from Japan if you have buildt them.