Trump is threatening 100% tariffs against a bloc of nine nations including Brazil, Russia, India, China and South Africa if they act to undermine the U.S. dollar.

Trump said Monday on Truth Social 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.