The complaint against the U.S. has been planned since March when Trump first announced plans to hit Europe and other allies with the metals tariff.
"When Bush was putting tariffs up, there was always a side communication, saying, 'We have to do this for domestic reasons, and it's not going to last forever; we'll take it away soon, ' " said Guntram Wolff, the director of Breugel, a Brussels think tank that specializes in economics.
Massive US tariffs on European Union steel imports came into force on Friday as Britain made it clear a trans-Atlantic trade war would be bad for both sides.
The EU threatened tariffs on Harley Davidson motorcycles and bourbon, measures aimed at the political bases of U.S. Republican legislators.
The European Union was "a peace project, including on trade", he said.
After the measures were announced on Thursday, the UK's worldwide trade secretary Liam Fox also dismissed Mr Trump's claim that the tariffs were for security reasons . The metal levies, which act like a tax on imports, had already taken effect in much of the rest of the world, and Trump plans still more tariffs on $50 billion of products from China in retaliation for what he calls decades of theft of American know-how.
In Canada, Prime Minister Justin Trudeau said the tariffs were "totally unacceptable", and Canada announced plans to slap tariffs on $12.8 billion worth of US products, ranging from steel to yogurt and toilet paper. In the case of aluminum and steel, Trump is invoking a seldom-used clause of a 1962 law that gives him the authority to curb imports if they undermine national security.
"We are alienating all of our friends and partners at a time when we could really use their support", said Wendy Cutler, a former USA trade negotiator who is now vice president at the Asia Society Policy Institute.
"I think it really just boils down to this very mercantilist viewpoint that the US administration has that imports are bad, exports are good", he said.
"We have a huge problem with the American government, with the White House", Moisi said.
Following Saturday's conclusion of a three-day meeting of G7 finance ministers, Canadian Finance Minister Bill Morneau issued a summary saying the other six members want Trump to hear their message of "concern and disappointment" over the US trade actions. USA trading partners had demanded that the exemptions be extended or made permanent.
Even some Trump allies in Congress said the trade moves were misguided.
The defence industry in both countries are easily among some of the world's largest steel and aluminum consumers; indeed, it was hard to find a spot on the convention floor where a firm wasn't showing off a tank or ship made of steel or a plane made of aluminum.
"Over the long run, these tariffs will drive aluminum prices higher globally, increasing the cost of beer production for all brewers".
But as part of the efforts to address outstanding trade disputes, Europe will present a complaint before the World Trade Organisation against China's intellectual property practices, it confirmed on Friday.
"Trade was discussed in the G7 in the context of risks to global economic growth and it was highlighted by quite a number of participants", Dombrovskis said.
Macron told Trump in a telephone call that the tariffs were "illegal", and Merkel said the measure "risks touching off spirals of escalation that in the end hurt everyone".
In a clear reference to Trump, Macron added: "These solutions might bring symbolic satisfaction in the short term".
But, she added, "they also contribute to USA industry including in defence projects which bolster U.S. national security".
U.S. Treasury Secretary Steven Mnuchin speaks at a news conference during a meeting for the G7 Finance and Central Bank Governors in Whistler, B.C., on Saturday, June 2, 2018. Ross will also meet the German and French economy ministers.