The allies of the United States during the Vietnam War are South Korea, the Philippines, Australia, South Vietnam, and all of the other countries that are anti-communists. The Vietnam war is considered to be a very costly conflict that resulted in a very long war. It seems that this has stemmed from the conflict that was also occurring because of the cold war.
The cold war started with the issues of the United States with the Soviet Union. In the year 1964, the United States also decided to become involved in the Vietnam War. In the beginning, it was only North and South Vietnam that was against each other, but as time went on, more and more countries became involved in the war.