Markovic's tiny country is set to become NATO's 29th member on June 5.
All six major industrialized powers are trying to convince Mr. Trump of the merits of free trade, and the global threat of climate change. Later, as they took the traditional "family photo" group shot, the heads of state quietly kept their distance from Trump, who minutes earlier was caught on video appearing to push the prime minister of Montenegro out of the way to get to his spot.
Trump neither apologized nor paid attention to the European leader after he barged past him.
Mr Trump's controversial actions come a day after he implored North Atlantic Treaty Organisation to "stop terrorism in its tracks" following the Manchester attack and scolded member nations for - in his view - not meeting their funding obligations.
But he complained that "23 of the 28 member nations are still not paying what they should be paying. for their defence".
"We agreed on many areas, first and foremost on counter-terrorism", Tusk said after he and European Union chief executive Jean-Claude Juncker met Trump for over an hour. No, he didn't repeat his description of the Belgian capital as a "hellhole", but the contrast between Trump's warm embrace of Saudi autocrats and his awkward interaction with the democratically elected European leaders was hard to miss.More news: Kathy Griffin releases photo holding a severed Trump head
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President Trump has had, according to the White House, a successful maiden trip outside the U.S. But the bad news is he has to come home. He faced accusation from the United Kingdom of leaking sensitive intelligence.
It had, he said, also been agreed to adopt an "action plan" created to enhance NATO's contributions while alliance leaders also made a decision to increase support to the USA -led Global Coalition to defeat the Islamic State (IS).
Secretary-General Jens Stoltenberg said that joining the U.S. -led anti-Islamic State coalition "will send a strong political message of NATO's commitment to the fight against terrorism and also improve our coordination within the coalition".
The biggest idea of Trump's trip was to reorient USA foreign policy in the Middle East against Iran.
During the meeting, Trump did not restate commitment to NATO Article 5 - a provision of membership that says an attack on one member state is an attack on all member states. "Look at the millions of cars they're selling in the U.S; awful... we will stop this", he reportedly told the European Commission President Jean-Claude Juncker and European Council President Donald Tusk, according to the New York Daily News.