Trump lifts tariffs on imports of aluminum from Canada

US President Donald Trump signed a proclamation lifting tariffs on imports of aluminum from Canada, but warned that they could be reinstated.

"Imports of aluminum from Canada would no longer threaten to impair the national security, and thus I decided to exclude Canada from the tariff proclaimed in Proclamation 9704, as amended," Trump said in the Tuesday proclamation.

The proclamation, which adjusted imports of aluminum into the US, came after the US Trade Representative's office said last month it will resume duty-free treatment of Canada's aluminum retroactive to Sept. 1.

Trump, however, warned that he could re-impose the tariffs if there is a surge in imports of aluminum from Canada.

"I noted that the United States would monitor the implementation and effectiveness of the measures agreed upon with Canada in addressing our national security needs, and that I may revisit this determination as appropriate," he wrote.

The US and Canada share a deeply integrated aluminum market with combined trade of $12.9 billion in 2019. About 81% of Canada's primary aluminum production is exported to its North American neighbor.