Trump says a 25 percent tariff will be added to steel and a 10 percent tariff will apply to aluminum. Only Canada and Mexico - both partners in the North American Free Trade Agreement that is being renegotiated - were excluded from the tariffs. "We'll be doing something with some other countries".
Hours before the president signed an executive order implementing the new tariffs, trade ministers from 11 Pacific Rim countries signed a sweeping free trade agreement the USA had been part of until Trump withdrew a year ago.
President Trump said the unfair trading practices, particularly by China, has created dire circumstances for the industry.
Draghi also noted that putting trade restrictions on another country had benefited the US dollar in the past, but there was no guarantee of a similar reaction in the future.
Trade body UK Steel said the tariffs could have a "profound and detrimental impact" while the Community union demanded action to protect British jobs and avoid a "global trade war". "Our negotiating positions are absolutely unchanged".
The developments Thursday cap a week of frenzied lobbying by Canada, and come after the seventh round of NAFTA talks, which concluded Monday.
NPR's Philip Reeve tells Morning Edition that Brazil is gravely concerned about the US tariffs, saying that they will hurt trade relations and that the South American country has not ruled out sourcing its coal from elsewhere.
Height Capital Markets analyst Clayton Allen said AK Steel Holding Corporation (NYSE: AKS), U.S. Steel, Century Aluminum Co (NASDAQ: CENX) and Alcoa Corp (NYSE: AA) face negative market sentiment following exemptions for Mexico and Canada. But, just as he had one week earlier, the president forced his administration to take a "fake it 'till you make it" approach to global economic policy, by unilaterally tweeting a confirmation of the event.
The EU has warned that it could retaliate with tariffs on USA steel, agricultural and other products, such as peanut butter, cranberries and orange juice.
A deal exempting Australian steel from Donald Trump's tariffs could be done within two weeks after the president promised to help a United States' ally.
At the White House, officials were working to include language in the tariffs that would give Trump the flexibility to approve exemptions for certain countries.
While some of his suppliers are based in Mexico, which are exempt from the tariff along with Canada, others are located in Brazil.
Republicans in Congress have urged Trump to moderate his position, raising concerns the tariffs could hurt the economy and threaten the GOP's chances in the midterm elections.
"If we don't make the deal on NAFTA, and if we terminate NAFTA because they're unable to make a deal that's fair for our workers ... then we're going to terminate NAFTA and start all over again", he said.
Apply tit-for-tat tariffs on non-Third World countries (such as India) that have tariffs on USA products.
He also faced continued criticism from his Republican party, most notably House Speaker Paul Ryan who continued to lament Trump's move.
"We have some friends and some enemies where we have been tremendously taken advantage of over the years on trade and on military", he said.
"We should prevent a trade war situation from excessive protectionism, in which the entire world harm each other", Trade Minister Paik Un-gyu told a meeting with steelmakers.