"We will see what happens - just a loose meeting".
"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.
Dr. Claudia Major, a researcher at the German Institute for International Security affairs, said that Germany, in particular, does more for the alliance than spend on its own defense, including deploying troops to Afghanistan, "and eventually, two percent is an arbitrary measurement that does not say much about efficiency and output".
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.
Speaking at a media conference after two days of talks, Mr Trump said the US's allies had committed to raising their commitment beyond 2 per cent.
"We're going to ask that again", Trump said. "Trump wants to see our allies share more of the burden and at a very minimum meet their already stated obligations", Sarah Sanders told reporters A source close to French President Emmanuel Macron also played down Trump's words as rhetoric, saying "it is not a new demand".
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".
Germany, Europe's biggest economy, spends just 1.24 per cent, compared with 3.5 per cent for the US.
EU President Donald Tusk stepped up to the fight with his own salvo against Trump on Tuesday, telling him to "appreciate your allies" and reminding him Washington that Europe had come to its aid following the 9/11 attacks. Trump also prepared to make a previously unscheduled public statement, the White House said.
Trump has berated members of the alliance for failing to spend enough of their money on defense, accusing Europe of freeloading off the USA and raising doubts about whether he would come to members' defense if they were attacked.
Amid the tumult, British Prime Minister Theresa May sounded a call for solidarity among the allies, saying, "As we engage Russian Federation we must do so from a position of unity and strength - holding out hope for a better future, but also clear and unwavering on where Russian Federation needs to change its behaviour for this to become a reality".
Trump and Merkel later held businesslike talks on the sidelines of the summit.