They knew what it was like to be attacked by Northern communists; they went thru it too in 1950-1953, Korean War. Plus, the US asked them for help.
The answer is yes, South Korea was in the Vietnam War!
The war in Vietnam was similar to the US Civil War because the war involved North Korea versus South Korea.
It was both a civil war and a surrogate war with China and the USSR supporting North Vietnam and the US, South Korea, Australia, New Zeland, Thailand and the Phillipenes supporting South Vietnam.
The British fought in Korea, not Vietnam.
Korea, Australia, Phillipines, and Canada all pitched in during the Vietnam war alongside the U.S. effort to preserve democracy in South Vietnam.
Vietnam and Korea .
Besides the US; Australia, New Zealand, South Korea, Thailand, and the Philippines sent COMBAT units to Vietnam.
North Vietnam and South Vietnam. Also, to name just a few: the USA, China, Russia, South Korea, Australia, France, and England. A great many countries fought in the Vietnam War from 1945 to 1975.
The UN didn't fight in the Vietnam War; the UN was in Korea.
The UN wasn't really involved in the Vietnam war. It was more involved in the Korean war which happened a few years earlier. American's fear of commmunism seemed to be cemeted when North Korea attacked South Korea, America then asked the UN intervenean to stop the attack. Eventually they organised a military force to stop the attack.
The U.S got involved in The Korean war and Vietnam for many reasons. The U.S got involved in the Korean War because the United Nations called upon all member countries to help support South Korea. The United States had a relationship and treaties with South Vietnam so when the North attacked it was our duty to honor our relationship.
New Zealand, US, South Korea, South Vietnam, Philippines, Thailand.