The French .
French
The Japanese occupied French Indochina (now separated into Vietnam, Laos & Cambodia) during the Second World War.
Japan
During WWII, Japan occupied Southeast Asia. Vietnam is part of Southeast Asia.
Air war over North Vietnam. Ground war in South Vietnam; Riverine war in South Vietnam.
The answer is yes, South Korea was in the Vietnam War!
Korea was split at the 38th parallel and North Korea was occupied by Russia and South Korea was occupied by the U.S.
South Vietnam representing the free world, lost the war to the communists.
The Vietnam War demonstrated to the world, that the US would make a stand against communist aggression. The loss of South Vietnam was a temporary blow to US morale.
Air war-North Vietnam Ground war-South Vietnam
North Vietnam started the war against South Vietnam; the US went to the aid of the South.