Basically, the Vietnamese sides, north and south, each had allies and supporters. These allies joined with the troops in Vietnam. The US was on the side of the south. They lost.
It joined the ranks of other communist countries.
Nazi Germany and Japan .
British,France, Russia
In 1970 the United States wasn’t fighting the British and no Native Americans joined them.
There no longer is a North Vietnam, North Vietnam and South Vietnam were joined together after the Vietnam War.
No new countries joined in 2002. Prior to that, the last countries to join joined in 1995. The next set of countries joined in 2004.
Quebec's armies joined in on fighting overseas in WWII. However, it was strictly on a volunteer basis. Quebec's people were against Conscription [being forced into fighting].
Nowhere. They sheltered in their homes and several joined the Federals fighting as snipers against the Confederates who were attempting to seize the town.
They could no longer afford to keep fighting the war, especially now that the US had joined the war against them.
Stop communist aggression into South Vietnam.
Actually, it was in 2004. The following countries joined the EU.CyprusCzech RepublicHungaryEstoniaLatviaLithuaniaMaltaPolandSloveniaSlovakia