 During the ten @-@ month trial , several events occurred in America that intensified the nation 's anti @-@ communist sentiment : The Judith Coplon Soviet espionage case was in progress ; former government employee Alger Hiss was tried for perjury stemming from accusations that he was a communist ( a trial also held at the Foley Square courthouse ) ; labor leader Harry Bridges was accused of perjury when he denied being a communist ; and the ACLU passed an anti @-@ communist resolution . Two events during the final month of the trial may have been particularly influential : On September 23 , 1949 , Truman announced that the Soviet Union detonated its first nuclear bomb ; and on October 1 , 1949 , the Communist Party of China prevailed in the Chinese Civil War . 
