The latest skirmish in U.S. President Donald Trump’s trade war is highlighting how the Canadian province of Ontario provides electricity to some American homes and businesses.

Ontario is holding off on a 25% surcharge on electricity going into the U.S., Premier Doug Ford said in a joint statement with Secretary of Commerce Howard Lutnick—just hours after Trump threatened to impose a 50% tariff on all Canadian steel and aluminum products Wednesday, marking an escalation in the U.S.-Canada trade war.

President Donald Trump may have delayed most – though not all – of the tariffs he had imposed on Canada and Mexico, but that hasn’t stopped America’s northern neighbors from responding forcefully in retaliation.