Trump, who has imposed 25% tariffs on almost all products imported from Canada, has repeatedly said this year that the US has a “$200 billion” trade deficit with Canada – sometimes making the claim explicitly and sometimes using vaguer language about a supposed $200 billion subsidy or loss to Canada.

It's the latest twist in a fluctuating trade policy that has whipsawed markets and fanned worries about inflation and growth.

After declining to extend a 30-day pause for new trade levies targeting Canadian and Mexican imports announced last month, tariffs ordered by Trump took effect at 12:01 a.m. Tuesday. Trump has said the new levies are aimed at quelling illegal immigration as well as the flow of drugs like fentanyl into the U.S.