John Earl Haynes is an American historian. He specializes in twentieth-century political and intelligence history. For most of his career, he worked in the Manuscript Division of the Library of Congress. In this interview, he provides an in-depth summary of Soviet espionage in the Manhattan Project. He addresses the history surrounding well-known spies, including Julius Rosenberg, David Greenglass, and Klaus Fuchs, as well as lesser-known agents like Jacob Goros, Elizabeth Bentley, and Clarence Hiskey. Haynes also explains how the Soviet agencies the GRU and the KGB operated in the US in the 1930s-40s. He analyzes the successful and failed Soviet attempts to uncover American industrial and military secrets about the atomic bomb during World War II and the Cold War.