Callen is identified in [[Venona]] traffic under the cover name SATYR. Venona messages reveal Callen giving copies to the KGB of SWP correspondence, intimate information on [[Leon Trotsky]]'s widow, [[Natalia Sedova]], and financial reports of Trotskyist groups. | Callen is identified in [[Venona]] traffic under the cover name SATYR. Venona messages reveal Callen giving copies to the KGB of SWP correspondence, intimate information on [[Leon Trotsky]]'s widow, [[Natalia Sedova]], and financial reports of Trotskyist groups. |