In 1940, 1,200 tons of stockpiled uranium ore were shipped to the US by Sengier's African Metals Corp., a commercial arm of Union Miniere. Then, after the September 1942 agreement with Nichols, an average of 400 tons of uranium oxide were shipped to the US each month. Initially, the port of Lobito was used to ship the ore, but later Matadi was used to improve security. Only two shipments were lost at sea. The aerodromes in Elizabethville and Leopoldville were also expanded. Additionally, the mine was reopened with the help of the United States Army Corps of Engineers, which involved draining the water and retooling the facility. Finally, the Office of Strategic Services were enlisted to deal with the threat of smuggling to Germany.