In 1937, 5.7 percent of the Party were Jews yet they formed a majority in the government. Lenin himself (who was partly Jewish by ancestry) said that if the Commissar was Jewish, the deputy should be Russian: Stalin followed this rule. […] Many Jewish Bolsheviks used Russian pseudonyms. As early as 1936, Stalin ordered Mekhlis at Pravda to use these pseudonyms: “No need to excite Hitler!”

Simon Sebag Montefiore (Jewish historian) “Stalin: The Court of the Red Tsar”, 2003