Trump claimed America had been obliged to levy the metals tariffs as it has been exploited as the world's "piggy bank" under existing arrangements, but his counterparts were equally determined to protect "rules-based" worldwide trade.
As for the prospect of new trade deals touted by the Trump administration, Alden says they are a pipe dream.
The joint statement between the leaders of the U.S., France, Germany, the U.K., Japan, Italy, and Canada comes after President Trump refused to back down from his decision to impose worldwide tariffs on goods, including steel and aluminum imports.
And he was also asked for his thoughts on what Trump's move could mean for the future of the G7.
Image copyright JESCO DENZE What was agreed?
At the press conference Mr Trudeau insisted the US, Canada, Britain, France, Germany, Italy and Japan had figured out "consensus language" they could all agree to in the joint communique issued at the end of the G7 summit, despite the tensions with the US.
The ambassadors went on to call Trump's new tariffs on imports a significant step in a "protectionist direction" and concluded by calling for the two economies to "focus on what benefits us both".
"I highlighted directly to the president that Canadians did not take it lightly that the United States has moved forward with significant tariffs", said Trudeau. The remaining six members promised they "will promote the fight against climate change through collaborative partnerships and work with all relevant partners".
"His message from Quebec to Singapore is that he is going to meld the industrial democracies to his will - and bring back Russian Federation, " said Steve Bannon, Trump's former campaign and White House adviser. Earlier in the day, G7 countries announced they had raised more than $3.8 billion in an effort with other countries to send the world's poorest girls to school.
"We do not want the situation to escalate to a full-blown and merciless trade war, but hostile actions can not be left unanswered", French Finance Minister Bruno Le Maire said this week.
He left the summit early to travel to Singapore for a landmark meeting with the North Korean leader Kim Jong-un to try to persuade him to give up the country's nuclear weapons. "We can't lose it", he said.
The EU then announced tariffs on U.S. goods ranging from Harley-Davidson motorcycles to bourbon.
Yet, his threat to not sign the Communique also has the potential to upend, not only his gains with Trudeau and Canada, but a lot of the goodwill gained by the conference.
Media captionDairy wars: Why is Trump threatening Canada over milk? "Tariffs will come way down".
It was just hours after Trump left the G7 meeting, and then threw the whole thing into disarray by tweeting from Air Force One.
Neighbouring Canada, which hosted the G7, would be particularly hit by the tax change due to their extensive trade and industry links.
As Trump heads to Canada for this week's meeting of the G7 Group of Nations, the general consensus is that this is more like a G6 plus one- with the U.S. under Trump the odd country out.
Economics tops the agenda, although the meetings now always branch off to cover major global issues.
Led by the U.S., the group kicked out Russian Federation in 2014 over its annexation of Crimea and its support for pro-Russia separatists in Ukraine.