"We recognize that the American side is eager to get forward motion on NAFTA", Trudeau told CNN's Anderson Cooper, in one of his USA interviews.
"These are two separate tracks and in the NAFTA negotiations Canada will not be subject to any type of pressure", she said.
But as much as the steel industry has shrunk over the years, the US still produces millions of tons of it each year, Lardy says.
Considering the fact that the majority of America's imports of steel come from Canada, the European Union, Mexico and South Korea, the new tariffs also seem likely to damage US allies more than Trump's ultimate rival China.
Trudeau also expressed optimism about reaching a good North American free-trade agreement that will benefit Canada as well as the US and Mexico - despite Trump's constant refrain that the current deal is a bad one.
Trudeau said Canada had a lot more work to do and would press Washington to ensure the exemptions were permanent.
"On our end we are going to vigorously defend supply management", Couillard said, adding Quebec's farmers have already given up market share for other recently negotiated trade deals.
Trudeau also said it was in part due to the hard work of Canadian officials that Trump exempted Canada from the tariffs last week.
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In seeking to win a respite from the tariffs, American allies tried a mix of persuasion, threats, personal appeals, and diplomatic leverage.
Much of the steel imported today comes from friendly countries such as Canada, South Korea, Japan and the United Kingdom, with which the US has strong military alliances.
She is to meet US Trade Representative Robert Lighthizer, Commerce Secretary Wilbur Ross, Congressional leaders and others.
"The case in 232 is the argument that for national security reasons we need to maintain a high level of production of some particular commodity", says Nicholas Lardy, senior fellow at the Peterson Institute for International Economics.
28% of the volume of steel from Dofasco is exported to the United States, which would mean large impacts on the company if the tariffs are imposed.
Trudeau has wrapped up his tour of Hamilton, late this afternoon he was off to Sault Ste.
Unsurprisingly, news of the new tariffs has sparked a global outcry from major steel exporters around the world among which countries in Europe and Canada threatened to retaliate in kind.
Prime Minister Justin Trudeau is in Hamilton on Tuesday for the second leg of his cross-Canada tour of steel plants, and he's likely to get an earful from local steelworkers. While the penalties take effect later this month, Trump has encouraged countries to try negotiating exemptions for themselves.