In 1943 he became head of the East European Division , " the first of the six specialists who started the Russian-language program in the late 1920 's to become the head of a division of the State Department " . He then worked on Soviet issues in the State Department during the war , accompanying Harry Hopkins on missions to Joseph Stalin in Moscow . He worked closely with Roosevelt and was Roosevelt 's interpreter at the Tehran Conference ( 1943 ) and the Yalta Conference ( 1945 )
Yalta Conference
Yalta Conference
Charles E. Bohlen