With her husband, Robert Talbott Miller, III, she is alleged to have participated in covert espionage activities for the Soviet Union during the Stalinist period.
After the Spanish Civil War, the Millers returned to the United States and began operation of the Hemispheric News Service in New York City with Jack Fahy, a veteran of the International Brigades.
The publication centered on Latin American affairs, and Jenny was the operations Secretary.
Pelageya (or Polia) Habicht, a Russian native and very close friend of Jenny was exchanged in 1941 to the United States for Gaik Ovakimian, Soviet rezident and head of Soviet foreign espionage activities in the United States from 1934 to 1941 at the time of his arrest as an unregistered foreign agent.
Margaret (Peggy) Greenfield, a communist and economic writer and assistant chief of the Progress Reporting Branch, Division of Research, of the OPA was a frequent contact of Jenny.