In the days leading up to Thursday's announcement, the biggest trade move of Trump's presidency, key industry players and trading partners were still in the dark about the contours of the plan.
The EU is also maintaining a threat of counter-measures that would target USA imports ranging from maize to motorcycles, and may publish its list next week to allow industry and other interested parties to give their input.
"We are prepared and will be prepared if need be to use rebalancing measures", European Commission Vice President Jyrki Katainen told reporters in Brussels.
Many are calling this the ultimate irony as Trump acts to protect steel jobs in the US with his sweeping tariffs he is killing off steel jobs at the same time, making some big winners and other big losers.
"The misuse of the "national security exception" clause by the United States is wanton destruction of the multilateral trade system represented by the WTO and will surely have a serious impact on the normal global trade order".
For the G20 countries also including Turkey, worldwide trade agreements include as much opportunities as challenges.
He said that he had spoken to Turnbull, and that the two had agreed to move quickly to strike a deal on the tariffs.
The American president made his comments after crunch talks in Brussels between European Union negotiators and US Trade Representative Robert Lighthizer in an effort to defuse a bitter row that many fear could turn into an all-out trade war.
He exempted Mexico and Canada and hinted that U.S. allies such as North Atlantic Treaty Organisation members would also be spared if the tariffs hit national security.
Canada was the largest USA source of steel a year ago, followed by Brazil, South Korea, Russia, Mexico, Japan and Germany.
The steel industry in the USA employed approximately 147,000 people during 2015.
"It's extremely regrettable and I'd like to work on the Americans to exempt us", Hiroshige Seko, Japan's minister of trade and industry, told a press conference. But it added that it will "do its best" to get on the list of countries that are exempt from the restrictions.
Brazil and Britain were also quick to launch broadsides against the tariffs, which are worth billions of dollars.
"China would have to make a justified and necessary response". Said footage is embedded below, having been uploaded to the White House YouTube account, but left unlisted. "It's been an assault", Trump said Thursday.
The Trump administration said the President would meet members of the video game industry to talk about virtual violence shaping young people's minds, and yesterday he did.
Mexico, the third biggest trading partner with the U.S., was also exempted from Trump's steel and aluminum tariffs.
Hardt called the U.S. decision a "blow to transatlantic economic ties" and criticised U.S. President Donald Trump for seeking answers to U.S. economic problems overseas.
And European markets steadied in early trade.