The Defenders

'The Defenders' is a 1953 science fiction novelette by American author Philip K. Dick, and the basis for Dick's 1964 novel The Penultimate Truth. It is one of several of his stories to be expanded into a novel. The story was first published in the January 1953 issue of Galaxy Science Fiction.
Eight years ago a nuclear war began between the United States and the Soviet Union. American survivors evacuated to gigantic bunkers miles under ground. Sophisticated, radioactivity-immune robots called 'leadys' continue fighting the war on the devastated surface that is too dangerous for humans. The Soviets have similarly evacuated underground, and each side builds powerful weapons and vehicles for the remote-controlled war they only see from film that the robots deliver.
The security department asks Taylor, an American war planner, to observe the interrogation of a leady regarding the progress of the war.