While it's true that only a handful of the 28 member countries now spend 2 percent or more of their GDP on defense, a 2014 agreement gave all of them a decade to get to the 2 percent level.
"Everybody's talking about it all over the world, they're saying we're paying you billions of dollars to protect you but you're paying billions of dollars to Russian Federation".
During the president's remarks, he suggested countries not only meet their minimum commitment of 2 percent but increase it to 4 percent, Sarah Huckabee Sanders, White House press secretary said in a statement.
Rachel Rizzo, who works on Europe and North Atlantic Treaty Organisation issues at the Center for a New American Security, said that while it is positive that allies have reversed years of decreases in defense spending, pegging defense spending to an arbitrary percentage is problematic. "We're supposed to protect Germany but they're getting their energy from Russian Federation".
Her endorsement of the Trump-Putin meeting attempts to cut off awkward questions about Trump's commitment to Nato, an organisation he has openly and repeatedly criticised, which has dogged the ongoing Nato summit and threatened to undermine Trump's visit to London later this week.
Mrs Merkel told reporters: "I am very happy that today we are united in freedom as the Federal Republic of Germany". Instead, a series of events - a black-tie dinner with business leaders, a meeting with May and an audience with Queen Elizabeth II - will happen outside the bustling city, where Mayor Sadiq Khan has been in a verbal battle with Trump.
In Brussels, Trump Attacks Germany & NATO Secretary
Merkel, for her part, called the two nations "good partners" and said "we wish to continue to co-operate in the future". Trump asked. "When we stand together, also in dealing with Russian Federation, we are stronger", Stoltenberg replied.
The attack against a core ally comes just days before Trump is set to meet one-on-one with Putin. On 17 May, the Wall Street Journal reported that Trump is demanding that Germany drop Nord Stream 2 as one of the conditions for a trade deal with Europe that would not include high tariffs on steel and aluminium.
Funding has averaged at about $1 billion annually and Stoltenberg has said he expected that level to be met. But at the bilateral meeting he exulted: "We have a very, very good relationship with the Chancellor".
HORSLEY: We don't know what the two leaders said to one another behind closed doors, but in public, when they did their photo op for the news media, it was generally polite.
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. In that, we also defend the interests of the United States". The criticism and proposal dominated headlines with leaders, including Secretary General Jens Stoltenberg, widely accepting the complaint of unequality and pledging to spend more.
"I'm very pleased to have this opportunity for this exchange about the economic future and migration and the future of trade relations", Merkel said.