MOABS, daisy cutters, fuel-air bombs, F-18s, cruise missles, Tomahawks, Seasparrows, etc; those 3 - 4,000 artillery pieces wouldn't last one hour.
MOABs and Daisy cutters have their limitations. Alarge one being they need to be dropped from a large plane. Large planes = easy targets.
Tomahawks are nice, if you have them. F-18s, not really useful in certain types of terrain.
We have had a few easy fights. Remember Kosovo? We killed a lot Serb civilians but really didn't militarily dislodge the Serbian Army. The terrain in Korea is similar, meaning air power is nice but it won't do you much good.