Just four years after the U.S. detonated its nuclear bombs over Japan on August 6 and 9, 1945, the Soviet Union exploded its first nuclear bomb at a remote test site in Kazakhstan on August 29, 1949. Like Daniel Defoe’s marooned hero Robinson Crusoe, Herblock’s Mr. Atom discovers that the island is no longer his exclusive domain and registers the dismay experienced by the U.S. at the major shift in the balance of military power in the world.