The June 1940 Soviet occupation of Bessarabia found him on vacation there; he chose to remain and become a Soviet citizen. In September 1940 he began working at the Institute for Scientific Research in Chişinău, forced to flee in June 1941 following the province's recapture by Romania. Ending up in the Karaganda area, for nearly two years he was a teacher, school director, miner and party activist on a kolkhoz, until being sent to Moscow in 1943 to resume his studies. An active member of the Romanian communist exile circle in the Soviet Union during World War II, he worked in the Romanian-language division of Radio Moscow (1943–1945); contributed to TASS and to "Graiul liber", the newspaper of Romanian prisoners in the Soviet Union (1943–1946); and was a teacher at the Romanian section of the anti-fascist school for prisoners (1944–1946), heading it in 1945. A member of the Communist Party of the Soviet Union, he undertook the latter task as a party employee, helping indoctrinate Romanian prisoners. He also studied political economy at the Plekhanov Moscow Institute of the National Economy from 1943 to 1946 on a scholarship from the Chişinău institute. He taught there as well during his last year of study, but did not graduate because he left the country. He was brought back to Romania in June 1946 at the PCR's request, officially joining the party after recommendations from Leonte Răutu and Mihail Roller. From June to November 1946, he worked as instructor and assistant director at the central committee's economic section, beginning a rise that was aided by his start in an important position and his educated background.