Platoon (1986) - Vietnam war in film

The  tagline of the film is "The first casualty of war is innocence." This is shown through the narrative of taking an average American teenager, played by Charlie Sheen, who sees the war as his patriotic duty before he fully understands the psychological consequences of entering a war that was perilous and misjudged from the offset.

"Chris Taylor is a young, naive American who gives up college and volunteers for combat in Vietnam. Upon arrival, he quickly discovers that his presence is quite nonessential, and is considered insignificant to the other soldiers, as he has not fought for as long as the rest of them and felt the effects of combat. Chris has two non-commissioned officers, the ill-tempered and indestructible Staff Sergeant Robert Barnes and the more pleasant and cooperative Sergeant Elias Grodin. A line is drawn between the two NCOs and a number of men in the platoon when an illegal killing occurs during a village raid. As the war continues, Chris himself draws towards psychological meltdown. And as he struggles for survival, he soon realises he is fighting two battles, the conflict with the enemy and the conflict between the men within his platoon." IMDB

Even the Sergeants on the same side cannot agree, showing how at the time and in the 1980's people were divided on how they thought of the war. The war allowed for massive screw-ups by the US Army, such as the My Lai massacre of a village on March 16th 1968 which resulted in the deaths of between 347 and 504 civilians, including men, women, children and infants, simply because they thought they were Viet Cong. 

The war was by this point seen as entirely pointless, with the telling line  "we're gonna lose this war". Many Americans simply became disillusioned as to what they were fighting for, as well as there being a large drug problem in many platoons due to the stress of the war and the seeming lack of a likely victory for their side.

The film does not portray the war as an action or a sport, it shows the true psychological horrors of war that the American people had certainly realised by the 1980's.