WASHINGTON – After citing national security reasons for slapping tariffs on Canadian metals, Donald Trump escalated his attacks on America’s northern neighbor Tuesday, claiming its citizens were smuggling shoes across the border. Trump has angered Canada with his protectionist rhetoric, and has threatened to scrap the North American Free Trade Agreement (NAFTA) in favor of a new bilateral trade deal. “The tariffs are so massive. The tariffs to get common items back into Canada are so high that they have to smuggle them in,” he said in a speech Monday. “They buy shoes, then they wear them. They scuff them up, they make them… look old,” Trump continued. “Canada is not going to take advantage of the United States any longer.” Canadians returning to their country from abroad receive certain duty exemptions if they have been away for more than 24 hours. As part of NAFTA renegotiations, Washington wants Ottawa to expand these waivers to encourage Canadians to spend more in the US. Such a measure would negatively impact Canadian vendors. Nearly 4.9 million Canadians traveled temporarily to the United States between January and March 2018, according to Canadian figures.