US tariffs on steel and aluminium imports doubled to 50 per cent on Wednesday as President Donald Trump continued to ratchet up levies on foreign metals that he claims will help revitalise American steel mills and aluminium smelters.

The White House called the increased tariffs, which rose to 50 per cent from 25 per cent just after midnight Eastern time, a matter of addressing “trade practices that undermine national security.”

They were announced during Trump’s visit to a US Steel mill last week, and appear to be aimed at currying favour with steelworkers and the steel industry, including those in swing states like Pennsylvania, where US Steel is based.

In an executive order, Trump said the higher tariffs would “more effectively counter foreign countries that continue to offload low-priced, excess steel and aluminum in the US market and thereby undercut the competitiveness of the US steel and aluminium industries.”

The higher levies have already rankled close allies that sell metal to the US, including Canada and Europe. They have also sent alarms to auto makers, plane manufacturers, homebuilders, oil drillers and other companies that rely on buying metals.

Companies that use steel and aluminium to make their products criticised the tariffs, saying they would add costs for American consumers.

Economists have pointed out that tariffs on factory inputs such as metals risk slowing US manufacturing, since they raise prices for factories. By adding to the cost of making cars, drilling for oil and building data centres, steel tariffs could slow other goals of the Trump administration.

US unions and major companies such as US Steel, which have significant lobbying networks, have argued that tariffs are necessary to keep them in business. But foreign governments have bristled at the idea that their steel exports are a national security threat to the US, in part because its demand for the metals far exceeds the country’s current ability to produce them.

Canada is the largest foreign supplier of both steel and aluminium to the US.

New York Times News Service