OTTAWA - Donald Trump has put Canada on notice that he is taking aim at its much-coveted supply management system that protects the dairy industry.

Trump levelled the threat during an event at a Wisconsin factory where he unveiled his "Buy American-Hire American" executive order.

He says he will seek "fair trade" with all of America's trading partners "and that includes Canada."

Trump says "unfair things" have happened in Canada to U.S. dairy farmers.

Finance Minister Bill Morneau will tell this week's meeting of G20 finance ministers in Washington that Trump's executive order runs contrary to Canada's trading interests.

Senior finance officials who briefed reporters on the meetings suggest the order would run counter to protections Canada has secured through the North American Free Trade Agreement.