Trump's tweets from Air Force One, which was flying him to Singapore for next week's summit with North Korea's Kim Jong Un, came just as Canada released the group's official communique, which took a generally positive view of the leaders' positions on trade matters even though there were tensions with the U.S.
President Donald Trump delivered a stern warning on trade to foreign countries at the Group of Seven summit on Saturday, advising trading partners not to retaliate against US tariffs on the imports of steel and aluminum.
Trump gave "a long, frank rant", the official said, repeating a position he carried through the 2016 U.S. election campaign into the White House that the United States had suffered at the hands of its trading partners, with French President Emmanuel Macron pushing back on the assertion and Japanese Prime Minister Shinzo Abe chiming in.
A G7 summit dominated by disagreement over trade between the United States and its key allies has failed to deliver a breakthrough as the meeting enters its second and final day.
"Please tell Prime Minister Trudeau and President Macron that they are charging the USA massive tariffs and create non-monetary barriers", Trump said Thursday on Twitter. In the weeks leading up to the summit, he imposed tariffs on steel and aluminum from Canada, Mexico, and the European Union. "If it's not going to change we're not going to trade with them".
The response from Mr Macron suggests an end to what observers had noted was a budding "bromance" between the French president and Mr Trump.
Here's a World Bank graph of trade-weighted average tariffs for the G7 countries - with United States almost identical to UK/Italy/France/Ger, higher than Japan/Can.
While Europe's leaders have often allowed Germany and France to coordinate a common stance at worldwide gatherings, Conte raised eyebrows at the start of the summit by siding with Trump on the issue of Russia's readmission to their club.
Europe, Canada and Japan are largely united in opposition to Trump's protectionism while trying to find ways to bridge the divide and avoid rupturing the G7, which in its 42-year history has tended to seek consensus on economic and other issues.
Macron said he and Trump held "open and direct" discussions, adding that he thought there was a way to get a "win-win" outcome on trade, though details remained unclear.
Canada wants a deal too, but Trudeau reiterated the government view that the U.S.'s proposed five-year sunset clause is a non-starter.
The statement made no reference to Russian Federation being invited back into the G7, but the leaders did say they would continue "to engage with Russian Federation on addressing regional crises and global challenges, where it is in our interests".
The US has slapped a 25% tariff on imports of steel and 10% on aluminium from countries including the United Kingdom and the rest of the European Union.
G7 officials had planned for their leaders to discuss ways to counter Russia's interference in their democracies.
"What this will look like in 2018 and potentially beyond is a more and more economically and politically isolated America, but the rest of the world is pretty much carrying on to the best of its ability just without the U.S.".
"He must mean there are 10 things on which we totally disagree", the diplomat said. Japanese Prime Minister Shinzo Abe stands next to Trump, also with folded arms, as French President Emmanuel Macron leans in next to Merkel.
The second and final day of the G7 Summit started with a working breakfast.
It shows German Chancellor Angela Merkel leaning over a table toward Trump, who sits with his arms crossed defiantly.