Interest in Indonesia on the part of the Soviet Union can be traced back to Joseph Stalin’s government (1924–1953), in particular, to his last decade of leadership (1945–1953). After Indonesia’s proclamation of independence in August 1945, the struggle received a positive response from the Soviet Union. Stalin’s government supported Indonesia’s fight for freedom from the Netherlands, which wanted to regain its control after the Japanese occupation. When the Netherlands finally recognized the Republic of United States of Indonesia (RUSI) in December 1949, the Soviet Union formally recognized Indonesian sovereignty and established diplomatic relations. The first two decades played an important role in Indonesia’s formation as an independent state and in uniting its territories, particularly West Irian. © The Editor(s) (if applicable) and The Author(s) 2023. This book is an open access publication.