Years of complex negotiations by industry and government leaders finally paid off last week with the entry into force of the United States-Mexico-Canada Agreement. But what should be a significant victory for all three countries now faces a dark cloud of uncertainty: The U.S. is threatening to reinstate Section 232 aluminum tariffs on Canada just days after the USMCA enters into force.

This move is illogical and unsettling to all of us who have worked so hard to get this far. The tariffs could trigger a new trade war with our second-largest trading partner, undermining the benefits of this important agreement at a time when U.S. businesses and consumers can least afford it. After all the progress that’s been made with Canada, after all the work that’s been done on the USMCA, the last thing anyone needs is an unforced error to undo it all.