The United States is once again imposing tariffs on some imported Canadian aluminum products and Canada is gearing up to retaliate with reciprocal tariffs.

It would be the second time the U.S. president has levied tariffs on Canada over free trade.

In a tweet posted just after 6 a.m., Trump said the countries have been "presiding over a massive devaluation of their currencies" which he says is bad for American farmers.

By taxing imported steel, Trump risked raising costs for the many U.S. industries that use steel, straining ties with American allies and defying the limits of his authority to unilaterally punish trading partners.

The U.S. Commerce Department said it determined Canadian exports do not warrant the tariff, but those from Mexico and China do.

Canadian exporters' confidence fell to a seven-year low in a survey released on Thursday amid the disruption caused by trade wars and the imposition of U.S. tariffs.

Canada's Foreign Affairs Minister Chrystia Freeland stopped by Regina's Evraz steel mill to celebrate the end of American tariffs.

Prime Minister Justin Trudeau says Canada's retaliatory tariffs on American goods were key to restoring free access to the U.S. market for Canadian steel and aluminum.

Late last week, a deal to lift steel and aluminum tariffs imposed by the U.S. on Canada almost exactly a year ago was reached.

Canada will move quickly to ratify the new North American trade pact, Foreign Minister Chrystia Freeland said on Saturday.