Axios.com's Jonathan Swan says he's going against his own administration's advice:

Why it matters: These tariffs have the potential to roil markets and affect relationships with allies. Trump is also touching the third rail of international trade law — he’s using an arcane trade law known as Section 232 to justify his actions. He’s saying “F You” to the World Trade Organization and arguing the global overproduction of steel and aluminum constitutes a national security threat to the U.S. He's also breaking with Capitol Hill and top officials — including Gary Cohn, James Mattis, Steven Mnuchin and Rex Tillerson — who have been arguing strenuously against these tariffs.

I'm really worried about it if he isn't convinced to back down, it could be serious trouble for the world economy.  This is different than with foreign policy relations,so far that's been handled by minions and Congresscritters going out and smoothing concerns by saying "he didn't really mean it, we're staying with NATO" or whatever. This is different, he's just doing it. No explaining,it's going to happen and from now on other countries simply won't want to trust anything anyone else says on economy, they'll figure they can't trust what Cohn or Mnuchin promises.

Canada, Brazil — but not China — will be hit hardest by Trump's ...

By Thomas Franck @ CNBC-3 hours ago

[....] Canadian and Brazilian steel comprised 16 percent and 13 percent of U.S. steel imports as of September 2017. China, frequently criticized politically for dumping cheap steel on trade partners, is not one of the top 10 importers of steel to the U.S.

In response, Canadian officials promised to respond to U.S. tariffs; Canadian Trade Minister Francois-Phillippe Champagne said the taxes would be "unacceptable," and said he'd take measures to defend the country's workers.

Other top sources of steel used domestically include South Korea, Mexico and Russia [....]

Europe on Trump tariffs: We will 'react firmly and commensurately to defend our interests'

By Patrick Allen @ CNBC.com, 52 mins. ago

• European Commissioner President Jean-Claude Juncker issued a strongly worded statement in response to President Donald Trump's decision to impose steel and aluminum tariffs
• Next stop for Europe: Taking the fight to the World Trade Organization
• Juncker said "unfair measures put thousands of European jobs at risk"

Trump’s tariffs will hurt all Americans 

by the Washington Post Editorial Board, March 1

Trump gets his tariffs — and much of the world plans to strike back

By David J. Lynch &Caitlin Dewey @ WashingtonPost.com, 3 hrs. ago

President Trump’s decision to levy tariffs on foreign-made steel and aluminum is expected to backfire on U.S. exporters as other countries file legal challenges at the World Trade Organization. Investors appeared shaken by the news, with the Dow Jones industrial average closing Thursday down 420 points for the day.

Gallup poll long-term graph on foreign trade:

from

In U.S., Positive Attitudes Toward Foreign Trade Stay High (link below)

By Jeffrey M. Jones @ The Financial, 15 hrs. ago

Americans' increasingly positive views of foreign trade have stabilized after spiking last year. A strong majority of U.S. adults (70%) see foreign trade as an opportunity for U.S. economic growth through increased exports rather than a threat to the economy from foreign imports (25%). Before last year, no more than 58% had held the positive view of trade.

The results are based on Gallup's annual World Affairs poll, conducted Feb. 1-10. The issue of trade received significant attention in the last presidential campaign, with Donald Trump and Bernie Sanders criticizing U.S. trade deals for their effect on U.S. workers and companies. Trump said he would replace the North American Free Trade Agreement (NAFTA) and the Trans-Pacific Partnership (TPP) with bilateral deals that would better protect U.S. interests. In his first week as president, Trump announced the U.S. was withdrawing from TPP, and his administration continues efforts to re-negotiate the terms of NAFTA  [....]

continued @

https://www.finchannel.com/world/america/71877-in-u-s-positive-attitudes-toward-foreign-trade-stay-high 

(because can't get embedded link function to work on this piece for some reason)

NEW YORK TIMES:

Analysis Trump’s Tariffs Stoke Fears That Trade War Will ‘Kill’ U.S. Jobs

By JIM TANKERSLEY 7:16 PM ET

• A global tit-for-tat could crimp economic growth, undermining the stimulation of President Trump’s deregulation push and his signature $1.5 trillion tax cut.
• “If the president goes through with this, it will kill American jobs,” said Senator Ben Sasse, Republican of Nebraska. “That’s what every trade war ultimately does.”

Around the World, Threats of Retaliation Against U.S. Exports

By ANA SWANSON 48 minutes ago

Be it Europe, Canada or Asia, other countries said they would respond to Mr. Trump’s steel and aluminum tariffs with restrictions of their own.

• Stung by U.S. Tariff Plan, Canada Takes a Deep Breath9:10 PM ET

• The Upshot: Steel Tariffs Are Economically Small and Symbolically Big

• A Guide to the Tariffs and the Threat They May Pose

WASHINGTON POST:

Canada ‘flabbergasted’ by Trump’s tariff proposals

It was unclear which countries would be subject to the steel and aluminum tariffs, but Canada is the largest exporter of those goods to the United States. The foreign minister threatened retaliatory measures if Canada isn’t exempted.

• By Alan Freeman

Shortly before Trump announced tariffs, his former adviser dumped millions in steel-related stocks

Trump may prosper from tariffs even if this Ohio steel town doesn’t

The Macroeconomics of Trade War

By Paul Krugman @ NYTimes.com, March 3

Will Trump back down from his urge to start a trade war? Nobody knows; the thing is, he’s been an ignorant trade hawk for decades, he’s feeling beleaguered on many fronts, and word is that his doctor has told him to eat fewer burgers. So there’s surely a lot of pent-up rage that he’s all too likely to take out on the world trading system, especially when he tweets stuff like this:

Donald J. Trump✔@realDonaldTrump

The United States has an $800 Billion Dollar Yearly Trade Deficit because of our “very stupid” trade deals and policies. Our jobs and wealth are being given to other countries that have taken advantage of us for years. They laugh at what fools our leaders have been. No more!

12:43 PM - Mar 3, 2018

So it’s worth asking what would happen if Trump really did try to close the trade gap – it’s actually $500 billion, not $800 billion, but who’s counting – by imposing tariffs [....]

From establishment GOP guys:

Tariffs Are Taxes

By Larry Kudlow, Arthur B. Laffer & Stephen Moore @ NationalReview.com,  March 3

One of the ironies of trade protectionism is that tariffs and import quotas are what we do to ourselves in times of peace and what foreign nations do to u‎s with blockades to keep imports from entering our country in times of war.

Or consider that we impose sanctions on U.S. enemies such as North Korea, Russia, and Iran because we want them to feel the economic pain of being deprived of imports.

But now we are imposing sanctions on our own country, putting up tariffs supposedly to make Americans more prosperous.  If ever there were a crisis of logic, this is it.

President ‎Donald Trump genuinely believes that his steel and aluminum tariffs will save thousands of blue-collar jobs. And we know from our interactions with him that he truly cares about these workers in Pennsylvania, Ohio, and other Rust Belt states. We do, too, and we don’t want factories to shut down.

But even if tariffs save every one of the 140,000 or so steel jobs in America, they put at risk 5 million jobs in industries that use steel. These producers now have to compete in hyper-competitive international markets using steel that is 20 percent above the world price and aluminum that is 7 to 10 percent higher than the price paid by our foreign rivals.

Steel and aluminum may win in the short term, but steel-and-aluminum users and consumers lose.

Tariffs are really tax hikes [....]

And from Jonah Goldberg (who I don't know how to describe any more), excerpts from March 2 newsletter @ National Review titled A Conspiracy against the People,

President Trump shares with President Obama the idea that nations compete with each other economically. They don’t.

Not long ago, Republicans waxed quite righteous about the Obama administration ‘picking winners and losers’ in the economy.

What’s Populism Got To Do With It?

The funny thing is that this move toward protection is celebrated or condemned as a fulfillment of Trump’s “populist” agenda. I get that we label protectionism “populist” these days — though I’m old enough to remember when protectionism was a technocratic cause. But populism is supposed to mean putting the interests of “the people” first. (The problem with populism is that populists never mean all the people; they only mean their people.) And this move isn’t in the interests of most people. How is it “populist” to punish over 300 million consumers and the 6.5 million workers in steel-consuming industries for the benefit of 140,000 workers in the steel-producing industry? Trump says trade wars are “good” — but when other nations retaliate, farmers, truckers, manufacturers, and Americans in general will pay the price 

This isn’t populism in any literal meaning of the word; it’s elitism of the rankest sort. The president is abusing a law beyond its intended purpose to heap favor on a specific industry, while telling Americans that they aren’t paying enough for cars, aluminum cans, and countless other goods. Despite the fact that the U.S. steel industry already provides 70 percent of the steel used in America. This is literally conspiracy against the public [....]