Sci-fi Radio (ep26) Yanqui Doodle by James Tiptree Jr.

Yanqui Doodle by James Tiptree Jr. aka Alice Sheldon
The story is about a soldier in a Latin American country of the near future, one where American troops are fighting against a popular rebellion of "Guévaristas" and are given a variety of drugs by their commanders to make them into "berserkers" and then to help them sleep at night after they have committed atrocities.