To fight the Korean War was an important step to stop communism from spreading. If the United States would not have fought the war, communism would have spred and that was what had to be stopped. The domino effect could have continued to spread when this war was not fought.
Cons:
Thousands of American lives were losti n this war in a place that most Americans never even heard about. To many it seemed worthless and there was no reason to fight this war. Why should Americans care about something that is halfway around the world?