have you ever actually studied the korean conflict?
the task force there certainly won battles on the tactical end especially before china over run chosin
sorry tried typing out a response in time it took to load a battle, pretty much America and more importantly its Marine and Army response held the Pusan perimeter against a much larger and much more well equipped NKA force until the Landings at Inchon.
Then we proceeded to rout the NKs and camp for the winter along the NK CN border (at chosin ) this is where Chesty Puller became his final form and single handily fought off 500k red chinese (smug dog not totally like this , but he was there) Even while having to stage a retreat back to inchon the US and UN forces inflicted massive casualties on the Chinese counter. (like many thousands )
The withdrawal itself also saw that almost all American war material and a good number of civilians escape to the safety of the south Via the US navy. Then after the fluid first 2 years of the conflict it turned into a quagmire of heavy shelling and fixed lines much like what exists today on the DMZ.
In reality North Korea and to an extent China were spent by the fighting they put up (which only just staved off a complete defeat) and political power in the US wanted to find a solution in the non atomic means so we didn't escalate further . . .