"We're negotiating right now NAFTA and we're going to hold off the tariff on those two countries to see whether or not we're able to make the deal on NAFTA", he said.
But as much as the steel industry has shrunk over the years, the USA still produces millions of tons of it each year, Lardy says.
Trudeau told another USA network that he sees them as separate issues: "We don't link together the tariffs and the negotiations with NAFTA", he told CNBC in an interview from a Quebec aluminum plant Monday.
The U.S. government has been dropping hints that the decision to excuse Canada and Mexico from tariffs on steel and aluminum might only be temporary, and somehow dependent on the result of trade negotiations.
Also given preference are certain countries such as Canada with which the USA has reciprocal trading agreements. On Friday, European Commission President Jean-Claude Juncker discussed potentially imposing tariffs on blue jeans, bourbon, and Harley-Davidson motorcycles - three iconic American exports.
Later, Canada and Mexico were exempted from the imposition of the trade tariffs.More news: Billionaire Elon Musk Has A Secret Comedy Project In The Works
Trudeau called his American counterpart during a tour of aluminum facilities in Quebec, on a day the prime minister did American television interviews to promote the integrated Canada-U.S. economy.
Trump said last week he would impose import tariffs of 25 percent on steel and 10 percent for aluminum, effective later this month, but exempted Canada after an intense lobbying campaign arranged by Ottawa.
Trump recently exempted Canada and Mexico from tariffs on steel and aluminum, although the US government has been dropping hints that the exception is only temporary.
There's no question steel is an essential part of a wide range of weapons and other goods used by the military, from tanks to battleships.
"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.
"We are ready to take action whenever action is required. we had your backs last week and we always will", Trudeau said after visiting a Rio Tinto Ltd (RIO.AX) (RIO.L) smelter in Alma, Quebec, his first stop on a tour this week of Canada's steel and aluminum regions. Later this week Trudeau is due to visit the steel town of Hamilton, where workers are on edge. Marie, Ont., and Regina, Sask. Brazil, which is the second biggest supplier of steel to the United States after Canada, remains open for a dialogue to reach an understanding with the United States and is talking to other countries to learn about measures they are considering, he said.