Was Oppenheimer a Communist sympathizer?

J. Robert Oppenheimer was indeed a Communist sympathizer during the 1930s. However, his involvement with the Communist party was more about practical efforts, such as helping Jews escape from Nazi Germany, than about ideological alignment with Communism itself. Richard Rhodes clarified that while Oppenheimer attended some meetings encouraged by his girlfriend, Jean Tatlock, who was a Communist party member, there is no evidence to suggest that he shared information or had any affiliation with the Soviet Union during his work on the atomic bomb. Oppenheimer himself found the theories of Marx unconvincing when he read them 1.