In the film, the American squad come across a bunch of desserted buildings. They soon realise a sniper is hiding, and one-by-one, picks them off until there is barely any left. When the find the sniper, they discover that it's actually a young woman.
It gave me an idea for a similar scenario. It doesn't have to be set in Vietnam, but a young woman is forced to pick up a gun after foreign soldiers come and invade their land. Soon, her kill count becomes the stuff of stories amongst the enemy soldiers. However she slips up one night, gets caught. I'm not thinking rape here, but they enjoy having their fun with her and she is humiliated by them, beaten to give up information, forced to run through dangerous streets to give ammunition to separated squads, all the while she has a sniper's scope on her. Stuff like that.
Any one interested?