Iran's early nuclear program originated during the mid-20th century under Western cooperation, notably through agreements with the United States via the Atoms for Peace program, which provided its initial research reactor. In subsequent decades, as Iran pursued the development of independent civil and military atomic capabilities, foreign technical assistance, heavy water technology blueprints, and engineering expertise were largely acquired through clandestine procurement networks, alongside foundational state-to-state contracts with Russian entities for the completion of the Bushehr nuclear power plant.