Prior to World War II, iron ore from Iron Knob was also exported to Japan. In the financial year 1935–36, 291,961 tonnes of ore from Iron Knob was shipped there via the seaport of Whyalla. This became a controversial matter in the late 1930s due in part to Australia's known reserves at the time being limited to Iron Knob and Yampi Sound in Western Australia. Japan was also considered an 'aggressor' nation following acts of war against China in 1937. Waterfront workers and seamen protested against the export of iron ore to Japan, leading to strikes and arrests.
