Canada will impose retaliatory tariffs on $C16.6 billion ($A16.93 billion) worth of US exports and challenge US steel and aluminium tariffs under the North American Free Trade Agreement and the World Trade Organisation.
The Canadian tariffs are set to go into effect on July 1 and stay in place until the US lifts its own measures, Foreign Minister Chrystia Freeland said, hours after the US said it would impose tariffs on aluminium and steel imports from Canada, Mexico and the European Union.
"The American administration has made a decision today that we deplore and obviously is going to lead to retaliatory measures, as it must," Prime Minister Justin Trudeau said at a news conference with Freeland on Thursday.
"We regret that. We would much rather move together in partnership."
The Canadian government released two lists of US products, proposing a 25 per cent tariff on the first list and 10 per cent on the second.
Freeland said a 15-day consultation period would give Canadians a chance to comment on the tariffs and the products covered.
The list included steel and aluminium in various forms but also orange juice, maple syrup, whiskey, toilet paper and a wide variety of other products.
It largely spares US farmers. Among the few proposed agricultural targets are farm chemicals and cucumbers.
Freeland said Canada would challenge the US tariffs under NAFTA's Chapter 20 and the WTO's dispute settlement process.
Trudeau also discussed NAFTA talks, saying Canada, the US and Mexico had come so close to a deal he had offered to meet President Donald Trump in Washington.
Trudeau said Vice-President Mike Pence told him on Tuesday that as a precondition for that meeting, Trudeau would have to agree to a five-year sunset clause. He refused.
"There was the broad lines of a decent win-win-win deal on the table," Trudeau said.