Philip K. Dick 
Second Variety [EPUB ebook] 

Second Variety is a science-fiction novelette written by Philip K. Dick and published in 1953.
After a terrible war between the United Nations and the Soviet Union, survivors live in a wasteland.
There, soldiers discover self replicating robots initially conceived to destroy the Soviet agents.
But the robots now seem to target everyone.
Can the soldiers survive this terrible and new threat ?
Second Variety was adapted into the 1995 movie Screamers.