US President Donald Trump has announced his administration will impose 25% tariffs on imports of steel and 10% on aluminium in an effort to protect domestic steelworkers and to ensure a domestic industry for security reasons. Mr Trump made protectionism a pillar of his presidential campaign, but during his presidency to date has not acted a great deal on such measures – until now. The announcement was welcomed by domestic steel and aluminium producers (whose share prices rose), but criticised by other sectors in the economy, including auto-makers, who will be affected either by increased material costs or retaliation from trade partners. The foreign minister of Canada, which supplies the US with 16% of its steel demand, said that “Should restrictions be imposed on Canadian steel and aluminium products, Canada will take responsive measures to defend its trade interests and workers,” while the Brazilian industry ministry said it would also consider action. China and the EU would both said they would consider tariffs on US agricultural produce (even though the EU already imposes tariffs on steel imports from China, Ukraine, Russia, Brazil and Iran). The White House is yet to finalise the details of its plans, but will announce them early this month.