Second Variety (Version 2) by Philip K. Dick (1928 - 1982)

First published in Space Science Fiction May 1953. "The claws were bad enough in the first place—nasty, crawling little death-robots. But when they began to imitate their creators, it was time for the human race to make peace—if it could!" When future war becomes so horrific that humans turn to machines and computers to design ways to kill each other strange things may happen. And DO in this classic Philip K. Dick story! (summary from the story blurb and Phil Chenevert)