was an expression of moral outrage stemming from the Japanese bombing of civilians in mainland China in the late 1930s. In June 1938, US Secretary of State, Cordell Hull condemned the slaughter and its "material encouragement." A month later, the Department of State notified aircraft manufacturers and exporters that the US government was "strongly opposed" to the sale of airplanes and related materiel to nations using airplanes to attack civilian populations. In 1939, the nonbinding embargo was extended to materials essential to airplane manufacture and to plans, plants, and technical information for the production of high-quality aviation gasoline. The measures resulted in the suspension of the export to Japan of aircraft, aeronautical equipment, and other materials within the scope of the moral embargoes. As Japanese purchases of items other than aircraft and aeronautical equipment were minuscule, the moral embargo ultimately stopped the exportation of arms to Japan. End of commercial treaties Following the failure of diplomatic efforts to protect endangered American lives, rights, and economic interests in China, America considered commercial retaliation against Japan, Japanese authorities, or Japanese-sponsored agents in China. The American government felt that its 1911 commercial treaty with Japan was not affording an appropriate level of protection to US commerce in areas within or occupied by Japan. Simultaneously, Japan's position under the treaty, as a most favoured nation, legally prevented the adoption of retaliatory measures against Japanese commerce. The United States gave its six months' notice of its withdrawal from the treaty in July 1939 and so removed the primary legal obstacle for embargo. Effects The embargo, which halted the shipment of material such as airplanes, parts, machine tools, and aviation gasoline, was designed to be an unfriendly act. However, expanding it to include oil was specifically avoided. Since Japan was dependent on US oil, it was then thought that it would be a provocative step. The act was expanded in September of that year to include iron and steel scrap, an act that Japanese Ambassador Kensuke Horinouchi warned Hull on October 8, 1940, might be considered an "unfriendly act Controls were first authorized in 1940 in regard to munitions and similar materials essential to the defense effort, and they were extended in 1942 to all commodities. Always intended to be temporary, the 1940 act was successfully extended in 1944, 1945, 1946, and 1947. Postwar use After World War II, the Export Control Act was expanded to