Want this question answered?
South Vietnam was considered an ally of the US.
South Vietnam
Yes, of course. The US had many bases in South Korea and many of those were still bases in the Vietnam war.
No, Russia is to the west of Alaska (the northernmost state of the US, unconnected to the contiguous US).
USA lost to north Vietnam not south. The south was their ally.
South (RVN-Republic of South Vietnam)
North Vietnam started the war against South Vietnam; the US went to the aid of the South.
The US didn't invade South Vietnam. The Republic of South Vietnam asked for US help as they couldn't stem the Red Tide (communist infiltration).
There IS no North and South Vietnam, only Vietnam. After the US withdrew combat forces from South Vietnam, North Vietnam violated the peace agreement, invaded and conquered South Vietnam. Game over.
US, New Zealand, Australia, South Korea, South Vietnam, Thailand, Philippines.
north Vietnam took over south Vietnam
The US was an ally of South Vietnam; it was up to South Vietnam to repel the invasion from the north, with massive military assistance from the US (which, of course, ultimately failed).