Even though US President Donald Trump has shown some signs of flexibility on the imposition of import tariffs on steel and aluminium, the moves remain highly problematic and portend trouble ahead for the global trading system.

On March 1, Mr Trump announced tariffs of 25 per cent on steel and 10 per cent on aluminium. Citing national security concerns as the rationale, he said no countries would be exempted. Then on Thursday, when he signed the executive order which officially authorised the tariffs, Mr Trump agreed to exempt Canada and Mexico, pending discussions with these countries to revamp the North American Free Trade Agreement (Nafta). Mr Trump suggested that Australia, too, might be exempted when the tariffs go into effect.