As organizational secretary for the Communist Party in New York state in 1930, Peters was put in charge of building an illegal apparatus, or network, designed to support Soviet foreign policy. CPUSA and Comintern documents at the RGASPI archive in Moscow show that he headed the CPUSA underground apparatus from the early 1930s until Whittaker Chambers's defection in 1938. Peters was sent to Moscow for training with the Comintern in 1931 and was made a senior intern in the Anglo-American Secretariat. Returning to the US in 1932, the Central Committee assigned him to work in the "secret apparatus", where he remained until June 1938.