The heads of state - including President Donald Trump, British Prime Minister Theresa May and Italian Prime Minister Paolo Gentiloni - concurred at the meeting in Sicily that more can be accomplished in combating militant plots and ideologies.
Once more, he will likely be received warily, a president who ran on a campaign of "America First" with suggestions of disentangling the United States from global pacts, now engaged in two days of pomp and policy with the leaders of the United Kingdom, France, Germany, Italy, Japan and Canada. There was a "very intensive" exchange of views, she said.
The leaders meeting in Taormina, Sicily signed a declaration pledging to intensify the fight against terror in the wake of "the brutal attack in Manchester" that killed 22 people outside a pop music concert.
The United States, meanwhile, confirmed "a period of reflection" on the issue, he said. He has rolled back a number of Obama-era climate change measures, which will hamper USA efforts to fulfill its Paris pledges.
French President Emmanuel Macron reportedly discussed climate change with Trump at length on Thursday at a meeting in Brussels.
During his NATO speech, Trump did not explicitly affirm his commitment to Article 5 of the North Atlantic Treaty, which, when invoked, requires all member states to aid an ally under attack, as reported in The Atlantic.
Tusk already met with Trump on Thursday in Brussels, and said that while the two sides did not have a "common position about Russia", they appeared to be on the same page where the Ukrainian conflict was concerned.
He said the president, who has dismissed global warming as a "hoax", would make a final decision when he returned home, but stressed that he would put economic development first. The EU also has representatives.
Mrs May later told reporters she had had a "very good and productive discussion" with Mr Macron.
According to Donald Tusk, a former Polish prime minister who chairs summits of European Union leaders, the meeting won't be smooth. However, the Commission president confirmed that the issue of Germany's large trade surplus with the USA in the automobile sector was raised.
German weekly Der Spiegel quoted Mr Trump as saying in a meeting with European Commission President Jean-Claude Juncker on Thursday that Germans were "very bad" regarding auto exports to the US. It was expelled from the group in 2014 following its annexation of Crimea from Ukraine.
White House economic adviser Gary Cohn predicted "robust" discussions on trade and climate. "I believe the European Union and the USA will have a common policy on sanctions towards Russian Federation, too".
The leaders say they are targeting "propaganda supporting terrorism and violent extremism, online recruitment by extremists, radicalization and incitement to violence", and that they would work with youth and religious leaders, prisons and educational institutions toward that end.
Their two-day summit began Friday in the Italian city of Taormina.
"Today Italy is responding to the cliches with the superlative setting of Taormina, with the Theatre, with La Scala playing in a breathtaking setting, with Etna, with the beauty of the values of Sicily and the Sicilians", Renzi said on Facebook.
President Donald Trump has faced a much cooler reception in Europe than the welcome he received in the Middle East.
The Trump administration has pushed back against earlier G-7 agreements to reject protectionism - the practice of favoring domestic industries over foreign competitors through taxes or regulations.
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