In World War II, authorities were alarmed by his alleged contacts with the Soviet Union and NKVD agents, at the time when Ion Antonescu's regime allied itself with Nazi Germany and took part in Operation Barbarossa ("see Romania during World War II"). Eventually, he was arrested and interned, initially in the camp in Târgu Jiu. Although, like Preoteasa, he was originally close to Lucrețiu Pătrășcanu (who was himself an intellectual isolated among PCR members), Constantinescu associated with Gheorghiu-Dej/Emil Bodnăraș faction while in detention, endorsing successful moves against rival leader Ștefan Foriș.