Shares of steel and aluminum producers, including Cleveland-Cliffs (CLF) and Nucor (NUE), advanced Monꦿday after President Donald Trump said that he would be implementing a 25% tariff on imports o🎉f the two metals.

Trump told reporters on Air Force One as he was traveling to New Orleans for the Super Bowl on Sunday that he would be imposing the new duties today.

According to data compiled by trade data provider TradeImeX, Canada was the largest exporter of steel to the U.S. last year, followed by Brazil, Mexico, and South Korea. Canada was also the largest exporter of aluminum, accounting for nearly 40% of all of the metal coming into the U.S.

François-Philippe Champagne, Canada's Minister of Innovation, Science and Industry, wrote in an X post that "Canadian steel and aluminum support key industries in the U.S. from defence, shipbuilding and auto. ... We will continue to stand up for Canada, our workers, and our industries."

Trump also said he would be announcing retaliatory tariffs Tuesday and Wednesday against any countries that slapped them on U.S. products.

Shares of Cleveland-Cliffs and Nucor were up 14% and 8%, respectively, soon after markets opened, lifting the VanEck Steel ETF (SLX) 3%.