Before arriving a half hour late to the final day of meetings on Thursday, Trump tweeted that "the USA pays tens of Billions of Dollars too much to subsidize Europe", that Germany's oil and gas pipeline with Russian Federation is "not acceptable", and that allies must not only all reach the 2 percent defense spending guideline, but double that to 4 percent. Trump also prepared to make a previously unscheduled public statement, the White House said.
Despite that, Stoltenberg had been forced to call an extraordinary session of all 29 allies to discuss Trump's demands, in what officials said was one of the first of its kind at a North Atlantic Treaty Organisation summit for a decade.
"The communique is clear: it reaffirms the commitment to two per cent (of GDP)", said Macron, who was photographed smiling and sharing a hug with Trump yesterday despite recent tensions between the two. Pledges to spend 2 percent of national income on defence by 2024 must be met by January, he said - a dizzying idea for many countries which now spend just half that.
Referring to an ongoing investigation into ties between his election campaign and Russian Federation, he decried a "rigged witch-hunt" that was hurting the United States and its relationship with Russian Federation.
Trump has said next week's meeting with Putin "may be the easiest" part of his European tour.
The summit's dramatic, chaotic conclusion - complete with the USA president suddenly making demands following a formal communique - bore a striking similarity to Trump's departure from last month's G7 meetings in Quebec.
The president has been highly critical of the alliance, complaining the U.S. pays more than others. The important thing now is that we need to invest more - we need to get more money.
Mr Trump did not go into details about what specific countries had promised but suggested they would be increasing their rates of spending "at a much faster clip".
After throwing hand grenades for a day-and-a-half behind the scenes, insulting allies, and questioning the military alliance's very reason for being, the media was preparing for Mr Trump to do the same in a formal press conference - albeit hastily arranged.
In the end, leaders left with an awkward consensus, after hours in which Trump had been so aggressive in his approach with allies that reports made the rounds that he might pull the U.S. out. "And, as long as Russian Federation persists in its efforts to undermine our interests and values, we must continue to deter and counter them".
Trump is reported to have spoken of "grave consequences" if allies did not meet their 2 percent of GDP defense spending targets, saying that the United States could "go our own way" if his demands were not met. In the space of eight hours, Trump had moved from doubting the utility of the mutual defence alliance and provoking an extraordinary emergency session of its members to declaring the pact stronger than ever. However, EU officials claim that "while USA defense spending makes up 70 percent of combined allied governments' military budgets, just 15 percent of US expenditure is spent in Europe on NATO-related defense".
Mr Trump's early-morning tweets from Brussels had been typically critical. Tens of thousands of people are likely to protest in the British capital on Friday, while Trump is outside the city at May's country residence Chequers, before visiting Windsor to meet the Queen.