The British-Australian miner has been buying aluminum blocks on the open market produced by rivals in the U.S., instead of shipping them from its refinery and five smelters in Quebec. (Bloomberg)

Talking point: President Donald Trump restored and increased national security tariffs on aluminum to 25 per cent in March, then doubled the rate in June. The U.S. sourced about 53 per cent of its aluminum over the past year from Canada—where the energy-intensive metal benefits from cheap electricity in Quebec. Asked about the Bloomberg report, Rio Tinto spokesperson Simon Letendre told The Logic the company does not comment on its commercial strategy. In its half-year results released July 30, Rio Tinto reported US$321 million in gross costs linked to U.S. tariffs on Canadian inputs. It also said that while the market had adjusted quickly to the 25 per cent tariffs, prices do not yet reflect the 50 per cent rate.