US President Donald Trump has signed a proclamation temporarily amending tariffs on copper, aluminum and iron imports. The announcement on Tuesday morning included new rates and an expansion of existing industrial equipment categories. It also sought to incentivise foreign companies by introducing a lower duty rate in certain cases. Details shared by the White House reveal that two new categories of steel and aluminium derivative import products have also been added to the tariff list. Steel racks and aluminium lithographic plates will both be subject to 25% duties. Rate changes and ‘encouragement’ for foreign companies According to the Proclamation issued by Trump, tariff rates for agricultural equipment such as combines and harvesters have been adjusted from from 25% to 15%. The White House said this would also apply to “certain other equipment” without elaboration.