Most likely the US Army.
Vietnam is a communist nation.
The nation of Vietnam came into existence in 1975 (on paper in 1976). So are you asking about that Vietnam or the Vietnam War? There was no nation called "Vietnam" during the Vietnam War.
The US is an industrialized based nation, whereas Vietnam is an agricultural nation.
Formally it was two nations: North and South Vietnam. Yes, today it is one unified country (nation)...called Vietnam.
Vietnam is a communist nation; the US is not.
Thailand is a separate nation west of Vietnam.
VN was one nation.
The US has never fought with a nation called "Vietnam."
. . . a non-existent nation (Vietnam) .
It became a divided nation in 1954.
South Vietnam was already a sovereign nation by the time the US entered the nation. Its title was the "Republic of South Vietnam."
North Vietnam won the war, creating one nation...VIETNAM.
One nation instead of two.
Yes Vietnam is still a communist nation. Along with China, North Korea, Laos, and Cuba
The nation (country) of Vietnam didn't exist during the Vietnam War. Nor was any nation called "Vietnam" fighting the US. There was a country called North Vietnam that defeated the Republic of South Vietnam in 1975. The US was allied to the RVN (Republic of South Vietnam).
It is a communist nation.