If the United States imposes tariffs on imports of Canadian steel and aluminum, some Americans will lose their jobs and U.S. growth will suffer, Prime Minister Justin Trudeau said Wednesday.

Trudeau, speaking to reporters in Brussels, also reiterated that Canada would respond with countermeasures if need be. U.S. President Donald Trump is threatening tariffs on steel and aluminum as well as a broader tariff on all Canadian imports.

In 2018, during his first administration, Trump put tariffs on Canadian steel and aluminum as the United States was in talks on updating a continental trade deal with Mexico and Canada. Trudeau said the measures cost 75,000 U.S. jobs.

"We are highlighting the fact that there were job losses, significant ones, in the United States the last time that they brought in tariffs ... and that this will actually compromise growth and prosperity in the United States," he said.

Trump says the measures will aid struggling industries in the United States.

Roughly half all aluminum used in the U.S. is imported, with the vast majority coming from Canada. Imports from Canada in 2024 hit 3.2 million tons last year, twice the amount provided by the next nine countries combined.

Much of the Canadian supply comes from Quebec. Premier Francois Legault on Wednesday said Canada should consider export tariffs on products like aluminum "where they really need us."

Federal Finance Minister Dominic LeBlanc, in Washington for talks with U.S. officials, said Canada would not act until it saw what the administration did.

"What the Americans have said to us privately and what they have said publicly is that we have a number of weeks to work together," he told reporters.