"It's a very integrated supply chain as we know in the manufacturing sector across the three NAFTA countries".
The warning came after Mr Trump vowed Canada and Mexico would also be affected by his plans to impose steep tariffs on steel and aluminum unless he gets a "fair" deal to overhaul NAFTA.
"China wins when the American consumer has higher prices because of tariffs that don't affect Chinese behaviour".
"No, we're not backing down", Trump told reporters at the White House, adding that the USA has been "ripped off" by foreign countries.
Mr Trump's announcement last week that he would tax imported steel and aluminium has prompted worldwide reaction. Our Steel and Aluminum industries are dead.
The goal of the Trump administration is to get a free, fair and reciprocal trade but if there is a trade war, the USA is confident of winning it, the White House has said.
Anti-tax crusader Grover Norquist told CNBC on Monday he hopes President Donald Trump is only threatening steel and aluminum tariffs as a negotiating ploy to forge better trade deals for the United States.
"We are not supporters of trade wars".
Republican leaders of the House Ways and Means Committee, meanwhile, circulated a letter opposing Mr Trump's tariff plan.
Canada's Prime Minister Justin Trudeau waits to speak at the AppDirect office in San Francisco, Feb. 8, 2018.
"We wouldn't stand idly by, but ... if we did the same thing as the United States by taking steps that are against WTO rules, that would be like a children's spat".
$1 billion represents 12% of Ford's profit previous year and 7% of GM's, the analysis said.
Canada is the largest US trading partner and previous year shipped $7.2 billion worth of aluminum and $4.3 billion of steel to the United States.
Jean-Claude Juncker said plans to put tariffs on products such as Kentucky bourbon, Levi's jeans and Harley-Davidsons had not been finalised.
"People have to understand: our country, on trade, has been ripped off by virtually every country in the world, whether it's friend or enemy", said President Trump.
The big complaint from Trump and other American economic nationalists involves China, whose state-subsidized steel producers, they say, have been flooding the world market and driving down prices to levels where US companies can't compete.
Citing political as well as economic impacts, McIntosh said that "tariffs will also harm the pro-growth effects of the tax cuts, stall the economy, incite a trade war, and help hand the (2018 congressional) election to the Democrats". "So, we're very concerned", Senator John Thune said.
"The President has announced that this will happen this week". "We estimate the value of steel exports from Alberta to USA are in the hundreds of millions of dollars so there's a lot of jobs at stake, a lot of investment".
Among the falling steel stocks, Chung Hung Steel Corp. had lost 8.46 percent at NT$12.40 and Sheng Yu Steel Co. had fallen 3.02 percent to NT$27.25 as of 11:53 a.m. because the U.S.is their main flat steel sheet market.