What difficulties did us troops encounter in vietnam?

The Vietnam War, also known as the Second Indochina War,[54] and known in Vietnam as Resistance War Against America or simply the American War, was a war that occurred in Vietnam, Laos, and Cambodia from 1 November 1955[A 1] to the fall of Saigon on 30 April 1975. 
during the war the american troops have difficulties of the ff:
-jungle terrain, snakes
- tunnels made by vietcong that allowed them to stand air strikes 
- destroyed notion of traditional home front