President Donald Trump announced additional 25% tariffs on steel and aluminum imported from Canada on Tuesday morning, further escalating a trade war with the nation’s North American neighbor.

“Based on Ontario, Canada, placing a 25% Tariff on ‘Electricity’ coming into the United States, I have instructed my Secretary of Commerce to add an ADDITIONAL 25% Tariff, to 50%, on all STEEL and ALUMINUM COMING INTO THE UNITED STATES FROM CANADA, ONE OF THE HIGHEST TARIFFING NATIONS ANYWHERE IN THE WORLD,” Trump wrote on Truth Social.