During the Cold War, the United States felt that it was critical that they helped stopped the spread of communism globally. This idea is known as containment. In order to make sure that communism did not spread, the US got involved in multiple wars in the Asian continent. This includes the Korean and Vietnam War.
It was important that the US got involved with these wars in order to stop the spread of communism. A Communist system, like the one in the Soviet Union, would result in less rights for citizens. Along with this, the US would lose a future trade ally if they did not step in to help South Korea. To this day, we have a very good relationship with this country. We constantly get quality products from South Korea, including Hyundai cars and LG electronics.