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.
Striking a strident tone at the summit, Trump's aspirational target of 4 percent of gross domestic product (GDP) was above the United States own spending on defense.
"I have experienced myself how a part of Germany was controlled by the Soviet Union", Merkel, who grew up in communist East Germany, told reporters.
'It should never have been allowed to happen.
"Germany, as far as I'm concerned, is captive of Russian Federation because it is getting so much of its energy from Russian Federation", he said. "To me, this is nearly like propaganda, it really tells you how far out we're getting here and what sort of an influence that Trump is able to exert".
Trump has claimed on numerous occasions over the last week that the United States" more than 4 percent GDP contribution to the security of the group compared to its European allies is "very unfair' to the American taxpayer. "And I think that leaders are also looking forward to your thoughts about the meeting with President Putin later on".
He also suggested he could find time to talk to his "friend" Boris Johnson, who left Mrs May's Brexit negotiations in chaos by resigning as Foreign Secretary. "That is very good, especially for people in eastern Germany". Several experts explained that the president was likely referring, albeit incorrectly, to the commitment to devote 2 percent of GDP to defense spending.
The acknowledgement came during a pre-dinner interlude in Trump's long summit day.
TRUMP: "Frankly, many countries owe us a tremendous amount of money for many years back, where they're delinquent, as far as I'm concerned, because the United States has had to pay for them".
Merkel said it was very important to have such exchanges like the meeting she and Trump were having because "after all, we are partners. Ultimately, Germany will have nearly 70 percent of their country controlled by Russian Federation with natural gas".
Stoltenberg estimated European allies and Canada will add $266 billion to their military spending by 2024 and said, "this is really adding some extra momentum", apparently meaning Trump's pressure.
Rep. Ted Lieu (D-Calif.) reacted to President Donald Trump's attacks on fellow North Atlantic Treaty Organisation members Wednesday morning by tweeting a super basic memo to the president "to remind you who our allies are".
Trump did refrain from directly questioning NATO's objective or tearing up a joint communique, as he did during the G7 summit, so fears of the USA president unilaterally bringing the alliance to an apocalyptic end were avoided. "Well they could increase it immediately, tomorrow, and have no problem", Trump said. "He may be the only one, but that's OK with me".
Sen. Bob Corker, a Tennessee Republican, also criticized Trump's rhetoric.
"Dear America, appreciate your allies, after all you don't have all that many", he said.