Second Variety is a short story by Philip K. Dick, first published in Space Science Fiction magazine, in 1953. A nuclear war between the Soviet Union and the West has reduced much of the world to a barren wasteland. The war continues, however, among the scattered remains of humanity. The Western forces have developed "claws", which are autonomous self-replicating robots to fight on their side. It is one of Dick's many stories in which nuclear war has rendered the Earth's surface uninhabitable... Masterful sci-fi by a master!
