Peter Navarro, the director of the White House Trade Council, confirmed the plan at a joint meeting of the American Iron and Steel Institute and the Steel Manufacturers Association on Tuesday May 1 in Washington.

"Any country, or entity like the European Union, that is exempt from the tariff will have a quota ... and other restrictions necessary to make sure we defend our industries in the interest of national security," Navarro said in a brief speech to the gathering.

Navarro confirmed that the United States has reached agreements in principle with Australia, Brazil and Argentina and that "those will be finalized shortly."

Previous temporary tariff exemptions had been scheduled to expire Tuesday but were extended for 30 days while the various bilateral negotiations continue. Navarro said there will be no further extensions for talks involving Canada, Mexico, the EU or others. 

"Thirty days, that's it. A final 30 days, no more," he promised.

Navarro explained that he opened his talk to news reporters on Tuesday after becoming disappointed with the media coverage after the administration's work on Monday resulted in "a press release that could have been clearer last night." From the domestic metals producers' point of view, the initial announcement was met with some disappointment that necessary import restrictions were being postponed.

Navarro noted that South Korea had already agreed to quotas equal to 70% of the average annual volume in 2015-2017. He said that agreement "helps the Koreans because it stabilizes our relationship at a time when the president is doing something very historic" in promoting peace on the Korean Peninsula.

Aside from the trade curbs, Navarro emphasized that Trump's policies, including tax reform and "unleashing our energy sector," also would be positive for the metals industry.