Immediately after the war, the Soviet Union invaded and occupied northern Korea and took possession of Hansgirgs magnesium and heavy water plants in Hungnam. They transferred the technology back to Russia for integration into their own atomic bomb program. The U.S. Manhattan Project also utilized Hansgirgs electrolytic (CECE) process for heavy water production during the war and for many years thereafter. Many aspects of the postwar history related to both the U.S. and Soviet (now Russian) use of Hansgirg's processes remain classified.