Epstein was accredited to the United Nations as foreign correspondent for a number of Swiss newspapers and also contributed articles on the growing crisis in Europe to US magazines.
After the war, he was named as New York correspondent for a group of newspapers in West Germany; he contributed articles to German magazines and US periodicals like Plain Talk, Human Events, and National Review.
In 1963, he received an appointment to the Hoover Institution as an assistant to Dr. Stefan Thomas Possony, who conceived the Strategic Defense Initiative.
[6] In 1962, during the height of the Cold War, Epstein alleged that the Soviet Union had lost at least a dozen cosmonauts in undisclosed space disasters.
[11] In Operation Keelhaul (1973), Epstein revealed details of Operation Keelhaul, the forced repatriation at the end of World War II of four million Soviet citizens, expatriated White Russians who had emigrated from Russia after the Bolshevik Revolution, and other Eastern Europeans to the Soviet Union and countries within its sphere of influence after 1945.