Indeed, at his first meeting of the day, Trump said the US will not wait for an expansion in spending "over a 10-year period-they have to step it up immediately".

Labour MP Madeleine Moon, a champion of the anti-Brexit campaign group Best for Britain, said Mr Trump's comments were "a wake up call and a look into the future we face if Brexit goes ahead". "It's very unfair to our taxpayers".

Trump is reportedly considering imposing sanctions on the five European countries involved in the pipeline project. She said Germany could make "independent decisions".

In a stunning back and forth at Wednesday morning's bilateral breakfast at the ambassador's residence in Brussels, NATO Secretary General Jens Stoltenberg defended NATO's alliance as Trump continued to lob attacks on Germany. "Very supportive", Trump said. "But NATO has, of course, addressed energy security because we understand that there is a relationship between energy and security matters. We have highlighted the importance of this diversification of supplies to make sure that our energy systems are resilient".

At a news conference on Tuesday, Stoltenberg thanked Trump for his leadership in pushing member states toward the goal of spending 2 percent of their GDP on defense, while the USA spends closer to 3.5 percent.

"The United States is paying far too much and other countries are not paying enough, especially some. You tell me, is that appropriate?", he asked, while Stoltenberg listened. "I want to compliment the secretary general, he's worked very hard on this problem". "He may be the only one, but that's OK with me".

He vowed not to be "taken advantage" of by the European Union, which he accuses of freeloading by relying on the United States for its defence while blocking U.S. imports into the bloc, the world's biggest market.

We have just signed a joint EU-NATO declaration, which brings the cooperation between the European Union and NATO to the next level. They got rid of their coal plants, they got rid of their nuclear, they're getting so much of their oil and gas from Russian Federation. Four European members - Germany, France, Britain and Italy - combined pay 43.8 percent of the total.

It was an unusual criticism coming from Trump, who has appeared eager to cozy up to Putin and who has dismissed the USA intelligence community's assessment that Russian Federation tried to undermine Western democracy by meddling in the 2016 US presidential election to help Trump win. Not fair to the US taxpayer.

"Dear America, appreciate your allies-after all, you don't have that many".

"I look forward to having words with President Trump".

President Trump said his easiest meeting on his foreign trip to Europe during the next week may be his sit down with Russian President Vladimir Putin. "Frankly, Putin may be the easiest of them all - who would think?"

European allliance members were braced for criticism from Trump on defence spending, but his furious tirade at what should have been an amicable breakfast meeting appeared to take even North Atlantic Treaty Organisation chief Jens Stoltenberg by surprise. "I think it's not". "Just doesn't work!" he tweeted as he arrived in Brussels.

"It was also because of your leadership", Stoltenberg told Trump.

In a heated meeting in Brussels with the leaders of NATO, Trump claimed that Moscow now basically controls Berlin due to their dependence on it for energy.

"It's also because of your leadership, because your clear message", Stoltenberg responded.

"At the summit we expect to agree an ambitious package of measures to strengthen our deterrence and defence, increase our efforts on tackling terrorism and address the threats presented by cyber and hybrid warfare".