Naumenko settled in New York, where he published a two-volume book in 1962 and 1970 about the Repatriation of Cossacks entitled "Velikoe Predatelstvo" ("The Great Betrayal"). He was greatly embittered against Britain for the 1945 repatriation, and the matter was something of an obsession for him. Naumenko spent much time during his second exile visiting Australia, which took in a substantial number of Cossack refugees after 1945. The Austrian-born American author Julius Epstein described Naumenko in the early 1970s as living in a modest house in New York together with his daughter and son-in-law Nazarenko. He assisted the historian Count Nikolai Tolstoy with his books "Victims of Yalta" and his controversial book "The Minister and the Massacres". Naumenko spent his last days in a nursing home run by the Tolstoy Foundation in New York city, where he suffered from senility. The two volumes of "Velikoe Predatelstvo" were translated into English by the American novelist William Dritschilo under the title "The Great Betrayal" in 2015 and 2018.