USSR? I know, officially they didn't go there, but in reality they did and their soldiers died there. So did soldiers and officers from other nations of the Warsaw Pact (example- Ryszard Kukliński, although he survived).
I believe Russia supplied tanks and MIGs. Probably AK47s or their predecessors, and other things, esp intelligence. Remember, Communist China was younger, not as technological. This was a Cold War conflict.....all you heard from Republican politicians was the Domino Theory. They were certain all of Asia would go communistic if we did not keep South Vietnam non-communist.
I heard that from the Democrats as well...you know, JFK and LBJ really ramped up US involvement and it was DDE that kept our involvement minimal and Nixon/Ford that got us out.
I was also surprised. Australia's been one of the USA's staunchest military allies, joining in pretty much every war for the past 100 years with the US, even the unpopular ones like Vietnam and Iraq.
Possibly there were a lot of people who did the same thing I did: typed "Vietnam" and when it didn't work, thought that it was excluded from the start because it was the subject of the quiz. It's only a minute before the end, after trying every country in the vicinity and around the Pacific without finding the top 2 slots, that I remembered Vietnam was separated into two countries at the time.
That's generally seen as a different war, The First Indochina war. What Americans consider the Vietnam War is the Second Indochina war (or American war for the Vietnamese).
^ If France is to be excluded, then the range should be changed from 1955-1975 to somewhere around 1960 to 1975. JFK first sent "advisors" in 1961, and LBJ escalated by sending troops in 1965. So the US involvement would be closer to 14 years, not twenty.
France was at war in Vietnam 46 to 54 and was a colonial war, France fighting to keep it's colonial foothold in South East Asia. A different war to the North / South Vietnam war.
People just guess as many Asian countries as they can. "China" is more obvious than "North/South Vietnam" because those countries no longer exist (or at least are no longer referred to as such).
USA
Americans are the best and have won every war