Experts say the 1977 International Emergency Economic Powers Act is untested for imposing import tariffs and Trump's action will likely face swift court challenges that could set important precedents.

American importers will pay a new 25 percent tax on goods from Canada and Mexico and a 10 percent levy on products from China.

Canadian officials were informed that goods exported to the United States will be subject to a 25 percent tariff, with a lower rate for Canadian oil, starting on Tuesday.Credit...Ian Willms for The New York Times Trump tariffs: President Trump on Saturday followed through with his threat to impose stiff tariffs on Mexico,