Trump said last Thursday that he was slapping tariffs of 25 percent on imported steel and 10 percent on aluminum. Canada and Mexico were temporarily exempt from the tariffs - but the Trump administration has suggested that'd depend on a new NAFTA deal.
Trump stoked the fire on Saturday by suggesting even broader tariffs for the European Union if they don't address still-unspecified concerns.
"But I accept what the president said", Trudeau added, "that as long as there is a free-trade deal in North America there won't be tariffs".
Asked to respond to Trump's accusations that the EU is imposing barriers to US automakers, Malmstrom said that "it's hard to argue on Twitter over these issues, but the European Union is a very open market". "If not, we Tax Cars etc".
Trump drew on rarely used national security grounds to place a 25 percent tax on steel imports and 10 percent tax on imported aluminum.
Trudeau rejected calls by some Quebec union leaders to take a harder line in NAFTA talks and leave the table if Canada can not get a better deal.
"We don't carry out a global FONOPs program as the United States does", she said.
On average, the EU applies a 3 percent tariff on USA products, while the average tariff applied by the U.S.is 2.4 percent, the European Commission says, adding that isolating cars is "cherry-picking".
"Tariffs threaten to strangle the global golden goose", said Mark Zandi, chief economist at Moody's Analytics.
I talked to people in the metal fabrication industry after Trump's initial announcement, and the response to the tariffs was negative.
The tariffs might be popular in certain parts of the country where steel producers are major employers, just as Trump's obsession with favoring coal over other energy sources plays well in areas that happen to have voted for him.
Treasury Secretary Steven Mnuchin earlier said he expects countries in addition to Mexico and Canada to be exempted in the next couple of weeks.
The EU has been talking with partners about a legal challenge at the World Trade Organization to Trump's plan and is considering safeguards to prevent steel and aluminium, diverted from the United States, flooding into Europe.
According to an European Union statement, the average European Union tariff is 3 percent, not much more than the United States' average 2.4 percent. If our neighbors to the north call Trump's bluff, dairy farmers such as those of central NY - the No. 3 dairy producing state in the USA - could be collateral damage.
Steel workers build a structure in Ottawa, Canada.
During a joint White House news conference with visiting Swedish Prime Minister Stefan Lofven, the European Union has been particularly tough on the U.S.
Data last week showed that the USA trade deficit had jumped to an over nine-year high in January, with the country's shortfall with China widening sharply.