Although the 29-member military alliance's annual meetings have traditionally been fairly by-the-books events, expectations are different this year - thanks, in large, to Donald Trump.
Trump's comment came in response to a question by DailyMail.com at the White House just minutes after he was admonished by European Commission President Donald Tusk in response to Trump's repeated slams on North Atlantic Treaty Organisation alliance members who fail to meet spending commitments on defense.
"I would like to directly address President Trump, who has for a long time now been criticising Europe nearly daily, for, in his view, insufficient contributions to the common defence capabilities, and for living off the US".
But a Europe that better defends itself and buys more American gas gives Trump another advantage because it makes Europe more resilient militarily and less dependent on Russian gas.
"America, appreciate your allies - after all, you don't have that many". The Europeans abhor Trump's decision to impose steel and aluminum tariffs on a part of the world that is supposed to be the United States' partner.
Trump will visit Britain and meet Russian President Vladimir Putin in Finland's capital Helsinki after his stay in Brussels. It is always worth knowing: who is your strategic friend? Trump then heads to Helsinki to meet Putin.
Similarly, earlier on Tuesday the president tweeted, "Getting ready to leave for Europe".
Trump has, meanwhile, delivered on USA commitments to Europe.
"On top of that, we $151 billion on trade with the European Union".
While NATO members increased overall defense spending in 2017, for a second consecutive year, the United States was still largely outspending all other members.
Europe's biggest economy is on course to spend just 1.24 per cent of GDP on defence in 2018.
European Union leaders have been rattled by a recent encounter with Trump at the G7 summit in Canada, where the USA president belittled his democratic allies.
The 1.5 percent level forecast for NATO's European members in 2018 compares to 1.46 percent a year ago, 1.44 percent in 2016 and 1.42 percent in 2015.
While it's true that the U.S. provides roughly 22% of NATO's budget, this percentage is based off a carefully crafted formula that includes factors such as the size of a member state's economy.