In 1935 Bykov left abroad and served as ''Illegal'' [e.g. 'undercover'] ''[[Rezident]]'' of Razvedupr in the United States from 1936 to 1939. | In 1935 Bykov left abroad and served as ''Illegal'' [e.g. 'undercover'] ''[[Rezident]]'' of Razvedupr in the United States from 1936 to 1939. |