Vietnamese now are knowing the truth about the war. The country got the most benefit during and after Vietnam war was China, not Vietnam. After Vietnam war, China gained more lands and islands from Vietnam.
Zhou En Lai advised Ho chi Minh to divide Vietnam in half at Geneva Convention in 1954 with hidden agenda: Stratagem #5 Looting a burning house (趁火打劫, Chèn huǒ dǎ jié).
After Nixon-Mao treaty, Chinese Navy attacked South Vietnam at Paracel islands and currently control the Paracel islands.
Furthermore, China encouraged Khmer Rouge attacked Southern Vietnam border and killed Vietnamese in 1977. The climax happened when China invaded Vietnam in 1979 in the name “teaching Vietnamese a lesson" that killed over 60 thousand Vietnamese. In 1988, Chinese Navy suddenly attacked Vietnamese troop stationing in one among many islets from Spratly chain that kill 64 Vietnamese soldiers.
With a broad ambition of expansion from China, the leaders of Communist Vietnam got shocked and became alert.