"The steel and aluminum industries are vital suppliers to the Canadian manufacturing, energy, automotive and construction sectors".
It begs the question: what comes next?
"Our approach is we will not escalate, but equally we will not back down", Freeland insisted.
The tariffs will go into effect Sunday.
Prime Minister Justin Trudeau apparently reiterated that position to the president himself in a phone call on Friday.
While opposition parties have so far largely backed Prime Minister Justin Trudeau for standing up to Trump, their support could be tested once the US tariffs start to bite.
Trudeau announced Canada's intention to retaliate against Trump's tariffs at the end of May. When the TV reporter said Canada would retaliate by slapping tariffs on US products, "I went down the list, and they said gherkins".
Last week, U.S. Commerce Secretary Wilbur Ross expressed concerns about the world's overproduction and overcapacity of steel, saying the U.S. tariffs against Canada and other allies are created to force them into action. "The tariffs introduced by the United States on Canadian steel and aluminum are protectionist and illegal under WTO and NAFTA rules - the very rules that the United States helped to write", said Freeland in a statement.
Canada promised to react by imposing retaliatory tariffs on C$16.6 billion worth of USA exports and Freeland is due to outline exactly which goods will be hit, said the source.
"Faced with these unjustified tariffs, the United States will take all necessary actions under both US law and global rules to protect its interests", he said in the statement.
Freeland said U.S. tariffs left Canada "no choice" but to respond. That might change with the prospect of auto tariffs, though she stated that she hopes common sense would prevail. "A lot of people appreciate that", she said in an interview Friday.
"I don't think we'll see any reaction from the Trump administration".
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In comments filed with the US Commerce Department, GM said expansive tariffs could "lead to a smaller GM, a reduced presence at home and overseas for this iconic American company, and risk less - not more - US jobs". That threat could be a negotiating ploy to restart talks on the North American Free Trade Agreement.
"I'm not expecting this to create the kind of waves that are going to make any big difference", Mr. Watson said Thursday. "But from the US perspective, it took the threat of tariffs to do that, to prod Canada toward that goal".
Several countries, including Canada, are challenging that rationale with complaints against the USA to the World Trade Organisation (WTO).
At the time, Freeland told media in Ottawa it was the largest dollar-for-dolllar retaliatory tariff package Canada had ever threatened to impose against its southern neighbour.
On this front, Ottawa feels it has more work to do.
Ottawa would take measures to stop the dumping of steel in the coming weeks once it had finished consulting stakeholders, said Canadian Innovation Minister Navdeep Bains, appearing at the same event as Freeland.
Media captionDairy wars: Why is Trump threatening Canada over milk? "We are also concerned about further escalation and potentially wider and deeper impacts on Canadian businesses".
For example, Clark said as the price of products like steel rise, the increases will move through the system and hit the consumer in the wallet.
About 84% of Canada's primary aluminium production is exported to the US.
It also included money to help affected workers learn new skills and provided support for work-sharing agreements.
In 2017, about $14 billion of steel was traded between Canada and the United States.
"The measures announced today will help strengthen the competitiveness of Canada's steel and aluminum companies and contribute to economic growth while increasing the capacity of the industries to innovate, grow value added, support product and market diversification, and create and sustain jobs for Canadians".