THEY EAT THEIR OWN by Erik Lynd is a sci-fi short set in the future, after an extensive war with aliens. With no victory in sight for either side, a treaty was created, but some will never feel peace.
Jake just wants to be left alone with his dog Max, but one of the aliens crashes onto his land. This triggers a flashback of basic training, where the human soldiers are warned, "They eat their own." As a result, the surviving aliens become stronger, unless they are completely destroyed.
The ending is somewhat predictable, but the post-war setting is very intriguing. I wouldn't mind reading a full-length novel about the war itself.