You seem to forget that Vietnam war was a side effect of the Cold War. USSR and US fought through proxies in Cold War, Vietnam being just one instance. Another one before was Korean War which resulted in splitting that peninsula. I'd say your 20k is a bit low, might want to reconsider it with at least one order of magnitude.
Oh, and since we are splitting hair here about numbers, US started a 20 years war as result of just 3k deaths during 9/11. You and US government have another order of magnitude disagreement about what constitutes a "good" number of deaths as war causalities.