Mr Trump said countries needed to "step up, not over a 10-year period, they have to step up immediately" adding that other USA presidents had raised the issue but "did not do anything about it".
"I have to tell you that the atmosphere last night at dinner was very open, was very constructive and it was very positive", Kolinda Grabar-Kitarovic, the president of Croatia, told reporters. "President Trump wants to see our allies share more of the burden and at a very minimum meet their already stated obligations".
Throughout his presidency, Trump has railed against European allies for not paying more for the defenses and becoming too dependent on the United States.
"NATO is not a stock exchange where you can buy security".
Moreover, Stoltenberg argued Wednesday that the USA military presence in Europe, through the 29-country alliance, gives it an advantage in dealing with Russian Federation and projecting power in the Middle East and Africa.
Trump said he had been "extremely unhappy" with allies' low levels of defense spending before the summit, but was pleased "they have substantially upped their commitment" during a "fantastic" unscheduled crisis meeting on Thursday morning.
Trump has repeatedly slammed Merkel for supporting a new pipeline that would cement Berlin's client relationship with Russian Federation and increase Moscow's influence.
Merkel, who grew up in communist East Germany, shot back that she knew what it meant to be under Kremlin domination and Germany had the right to make its own policy choices.
"We need to look at the history of Putin, whether he's been a reliable energy supplier or whether he's used energy for geopolitical pressure, which he has", Bloomfield said. I am very happy that today we are united in freedom, the Federal Republic of Germany.
The issue dominated the president's public remarks after he arrived in Brussels on Tuesday, striking fear among European officials that the president would question the US' role in the alliance.
"Presidents have been trying unsuccessfully for years to get Germany and other rich NATO Nations to pay more toward their protection from Russia", Trump wrote.
"Germany is the second largest provider of troops, the largest part of our military capacity is offered to North Atlantic Treaty Organisation and until today we have a strong engagement towards Afghanistan", Merkel said, adding: "In that we also defend the interests of the United States".
Trump will meet the Russian leader in Helsinki on 16 July for their first summit amid an ongoing investigation in the USA into possible Trump campaign collusion with Russia.
Merkel, speaking through an interpreter, said the meeting was an "opportunity to have an exchange about economic developments. and also the future of our trade relations".
He also said he thought spending of 4 percent on defence - similar to the US level - would be the right level.
But Trump's claim that the U.S.is spending 4.2 percent of GDP is at odds with the Pentagon, which puts it at 3.3 percent.
"Many countries are not paying what they should", Trump said, seated across from a visibly rattled Stoltenberg.
- Thailand's Tham Luang cave to become museum to showcase boys' rescue
- Trump administration announces $US200 billion in extra China tariffs
- Things to look forward to in England vs India ODI series
- Cotton: Democrats’ Opposition to Kavanaugh a ‘Laughable Political Game’
- Liverpool fans will be pleased by Dejan Lovren’s continued form
- Canadian breastfeeding advocates alarmed by USA opposition to United Nations resolution
- Stormy Daniels arrested in OH , lawyer says
- London pub renames itself The Trump Arms ahead of presidential visit
- Thai cave rescue sees four more boys freed
- All-Star Game Final Vote 2018