After Indonesia's independence, Siregar went to the Soviet Union to further study socialism. He considered their system efficient and beneficial to the populace, which reaffirmed his ideology. He also praised Soviet writers who rejected cosmopolitanism and abstractionism. He published several dramas after returning to Indonesia, including the original "Tugu Putih" ("White Monument"; 1950), "Dosa dan Hukuman" ("Sin and Punishment", based on "Crime and Punishment" by Fyodor Dostoyevsky), and "Gadis Teratai" ("Lotus Blossom Maiden", based on a Korean folktale).