President-elect Donald Trump intends to follow through on his plan to impose sweeping tariffs on America’s top trading partners — a move that could come at a high cost to U.S. consumers. On Monday, Trump promised a new tariff on all products entering the U.

Trump said in a post to Truth Social on Monday that one of his first executive orders would be to hit Mexico and Canada with a blanket 25% tariff. Mexico and Canada are the second and third top suppliers of goods to the U.S., according to the Office of the U.S. Trade Representative. The U.S. imports the most goods from China.

The president-elect’s opening salvo in trade and border talks with the United States’ neighbors is casting a harsh light on the North American alliance.