Trump twice raised the possibility in the past few days of Russian Federation being brought back into the Group of Eight bloc, which shrunk to the Group of Seven - the U.S., U.K., Canada, Germany, France, Italy and Japan - after it was expelled following the annexation of Crimea from Ukraine in 2014.
Donald Trump's trade adviser has labelled Canadian premier Justin Trudeau a back-stabber unworthy of the U.S. president's time after the acrimonious end to the G7 summit.
Just as the G7 meeting of the world's leading industrialised nations had seemed to weather Mr Trump's threats of a trade war, the president backed out of the group's joint statement that Mr Trudeau said all the leaders had come together to sign. "Our tariffs are in response to his 270 percent on dairy".
Prime Minister Justin Trudeau, in a statement: "We are focused on everything we accomplished at the G7 summit".
Europe will not let Trump do "whatever he pleases", the German chancellor said, adding that "we will not allow ourselves to be deceived again and again".More news: The best reactions to viral Merkel, Trump G7 photo
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The French president expressed support for Trump in his expected summit with the North Korean leader, Kim Jong-un, but also warned his abrogation last month of a 2015 multilateral deal on the Iranian nuclear programme had cast doubt on the credibility of such agreements.
Peter Navarro watches as President Donald Trump speaks before signing Section 232 proclamations on steel and aluminum imports in the Roosevelt Room of the White House on March 8, 2018 in Washington, D.C. Or we'll stop trading with them.
"To answer this tweet and Trump's provocation at the G7 - if Russian Federation does not demonstrate any move forward, and we will invite them back, no one would understand this".
President Trump has refused to budge on his tariffs against Canada and European countries. Trudeau again denounced Trump's decision to invoke national security concerns to impose tariffs on aluminium and steel as "insulting" to the Canadian war veterans who had fought alongside U.S. allies. On Monday, he fired off a volley of tweets venting anger on North Atlantic Treaty Organisation allies, the European Union and again, on Trudeau.
Guy Verhofstadt, a former Belgian prime minister who as an MEP now co-ordinates Brexit talks for the European Parliament, mocked Mr Trump's temper and supposed closeness to Russian President Vladimir Putin in a series of tweets.
"He really kind of stabbed us in the back", Kudlow said. But in an apparent nod to Trump, the G7 also pledged to push for swift reforms to the World Trade Organisation which the United States president has said has been a "disaster" for his country. "I have instructed our U.S. Reps not to endorse the Communique as we look at Tariffs on automobiles flooding the U.S. Market!" he wrote.