"NATO is the force multiplier for the United States", Stoltenberg told reporters.
And despite Trump's outward rhetoric, the USA contribution hasn't gone down, suggesting that nervousness around the summit may be overplayed, said Michaels.
'I've said that many times for many years. The NATO chief said that the Europeans and Canada are projected to spend around US$266 billion more on defence by 2024. And It is not to sugarcoat Trump's gross failure to understand that U.S. power and influence in the world, essential underpinnings of his desire to put "American first", demand that the United States also work effectively with other countries, especially its allies and partners around the world.
Trump has requested closed-door meetings to take place without aides or the media involved.
May is grappling with a political crisis in London after Brexit Secretary David Davis and her foreign minister, Boris Johnson, resigned over her proposals for a "business friendly" Brexit, or exit from the European Union.
Divers embark on mission to rescue final 5 trapped in Thai cave
Musk on Sunday tweeted that he was sending a "kid-size submarine" to the rescuers in the hopes that it would be "useful". The boys, whose names have not been revealed, are being treated at Chiang Rai Prachanukraw Hospital in Muang district.
"If we all speak with the same voice and say you can come into the community of nations, you can be a major player for good - but not when you're violating your commitments, violating treaties, going into a sovereign nation and trying to kill a citizen as happened in United Kingdom.,' she said, referencing the Novichok attack in Britain".
Ahead of his first formal visit to Britain as US President, Mr Trump delivered a damning indictment of Mrs May's government saying it was in "turmoil" and Russian President Vladimir Putin may be less of a problem.
Trump's tweet on Tuesday echoed earlier posts on Twitter on Monday and his criticism at a rally of supporters in the United States last week, in which he said that Washington was unfairly carrying nearly all the cost of defending Europe. "Many of these nations owe massive amounts of money from past years, and not paying in those past years", Trump told the leaders of member countries. "Today, Europeans (collectively) spend on defense many times more than Russian Federation, and as much as China".
When asked if Putin was a friend or foe, the United States president said that he "really can't say right now".
He tweeted on Tuesday morning (Wednesday NZT): "Getting ready to leave for Europe. Charge us big Tariffs (& Barriers)!"
There was an estimated 4.87 percent increase in total defense spending by Canada and European allies in 2017, marking the third straight year that defense spending by those countries increased, according to North Atlantic Treaty Organisation. On Putin's wish list: an end to USA military exercises in Europe and the scaling back of US forces there. The summit also will offer Putin a chance to try to persuade Trump to lift some of the sanctions imposed on Russian Federation over its 2014 annexation of Crimea, its support for separatists fighting the government in eastern Ukraine and its alleged meddling in the 2016 US presidential election. Trump also said that it was in Washington's interest to foster better relations with Moscow and Beijing.