According to the global news agency his move "torpedoed what appeared to be a fragile consensus on a trade dispute between Washington and its top allies", Canada and the European Union among them.
German chancellor Angela Merkel's spokesman has not offered any advice on how to interpret a government photographer's viral shot of the G7 summit.
"This has solidified my belief that we, Europeans, should decide our fate by ourselves", the German leader said, calling on EU to be more active in defending its values and principles. "We will act too", she said.
Responding to the threat of new tariffs against the U.S., he said: "Fair trade is now to be called fool trade".
Merkel, whose office over the weekend released a photo of her leaning over a table before a seated Trump at a meeting with G7 leaders and aides, said she had "tried hard to find a compromise and we fought hard for it. this was an important announcement".
German Chancellor Angela Merkel, for instance, has insisted that tax payers in richer European Union member states should not end up paying for government failures in poorer ones.
President Trump left the meeting half-way, warning the G7 nations that if they don't remove trade barriers with the USA, they will face consequences. After Russia joined the group in 1997, the format was renamed G8.
Russian Federation has been shut out since its 2014 annexation of the Crimean peninsula from Ukraine, and has since earned Western condemnation for its military intervention in Syria in support of dictator Bashar al-Assad. "Preach Chancellor, preach!", "As US we apologise for his childish behavior", "Show him who's the boss Angela", a social media user said.
Turning to Russia, Merkel said she could imagine Moscow re-joining the G7 format at some point, but there first had to be progress in the implementation of the peace plan for Ukraine.
Looking ahead to the next major diplomatic encounter with Trump - a meeting of North Atlantic Treaty Organisation alliance leaders in July - "it won't be easy", Merkel said. And add to that the fact that the USA pays close to the entire cost of NATO-protecting many of these same countries that rip us off on Trade (they pay only a fraction of the cost-and laugh!).