One of the important differences between this film and other Vietnam films is that it's more or less split into two halves: the first half deals with the harsh, sometimes brutal basic training, the message of this being that in order to kill, you have to become dehumanised but tough. One student snaps under the strain and shoots himself.
The second half of the film deals with fighting in the war itself and questions the validity of what the soldiers are doing - was the war worth fighting and dying for?
In one especially shocking scene, the American soldiers are trying to take out a sniper who's picking them off. When they finally catch the sniper it turns out to be a young Vietnamese girl. In spite of this, the dehumanised soldiers are eager to kill her in revenge for the death of their comrades but they get Joker, the most human and sympathetic character, to kill her, which he does.
So the whole exercise is about dehumanisation and the lengths one has to go to be able to kill another human being and the effect it has on those who have to do the killing.
There is no satisfactory end to the film - the squad are still at war and must continue.
