U.S. President Donald Trump on Tuesday threatened to sharply escalate a nascent trade war with Canada in response to Ontario's export surcharge on U.S. electricity.

Trump said he would impose a 25 percent duty on Canadian electricity in response to Ontario's 25 percent surcharge on electricity for New York, Minnesota and Michigan.

This could lead to even higher prices for Americans, especially in northern states that rely on energy from Canada. Ontario Premier Doug Ford said the additional tariffs in Ontario, announced Monday, threaten to increase bills by $100 a month, CNN reported.

In addition, Trump said he would impose even larger duties on Canadian steel and aluminum than he had planned on Wednesday.

“Based on the fact that Ontario, Canada has imposed a 25 percent duty on 'electricity' coming into the United States, I have instructed my Secretary of Commerce to impose an ADDITIONAL 25 percent duty up to 50 percent on all steel and aluminum coming into the United States from Canada, one of the highest tariffed countries in the world,” Trump wrote on Truth Social.