U.S. President Donald Trump delivers remarks to U.S. troops at the Naval Air Station Sigonella before returning to Washington D.C.at Sigonella Air Force Base in Sigonella, Sicily, Italy, May 27, 2017.
First lady Melania Trump and Ivanka Trump also visited the separate area for women to pray at the Western Wall.
At a Group of Seven summit in the resort town of Taormina on the island of Sicily, Mr Trump pushed back against six United States allies, refusing to endorse a global climate change accord.
Almost every nation that signed that 2015 accord, including six other G-7 members, has agreed to reduce greenhouse gas emissions.
Daniela Schwarzer, research director at the German Council of Foreign Relations in Berlin, said the trip had confirmed Trump's "zero-sum game" view of the world in which you are either a victor or a loser and relationships are transactional.
McMaster adds, "we have back channel communications with a number of countries".
"I think we hit a home run no matter where we are", Mr Trump told the soldiers.
After meeting with Pope Francis at the Vatican, Trump traveled to Brussels for a North Atlantic Treaty Organization (NATO) summit and concluded his trip in Sicily at the G7 summit. Only five of NATO's 28 members meet the target: Britain, Estonia, debt-laden Greece, Poland and the United States, which spends more on defense than all the other allies combined.More news: Arsenal striker Welbeck looking forward to FA Cup redemption
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There had been reports that Donald Trump had been suffering from exhaustion during the trip, his first worldwide trip as president.
Leaders of seven wealthy democracies have reached a deal to give the Trump administration more time to tell them whether the United States plans to stay in the Paris climate agreement.
The president mentioned the terrorist attack Monday in Manchester, England.
The rest of the world was walking strong and united together, while the exhausted old United States was puttering along behind in a golf cart. Kushner's lawyer said he would co-operate with investigators.
His May 9 firing of former FBI director James Comey has raised concerns about whether he was trying to squelch a federal probe into his campaign's ties with Russian Federation past year.
As Trump headed home, European officials were left with mixed feelings: relief that he had been patient enough to listen to their arguments and unsettled by a Jekyll-and-Hyde figure who is still finding his way on the big policy issues. The Republican health care bill that passed the House faces uncertain prospects in the Senate after a Congressional Budget Office analysis that it would leave 23 million more Americans uninsured by 2026.
But that also seemed to undercut a popular criticism Donald Trump had for his opponents during the 2016 presidential campaign.