The split was starkest at Nato's headquarters, where Mr Trump used the dedication of a new building to lecture allies on their financial contributions.
Optics-wise, things didn't fare much better, with passive aggressiveness out in full force.
UNIDENTIFIED BAND: (Playing "The Star-Spangled Banner").
"Every US President since Truman has pledged support for Article 5-that US will defend Europe".
US President Donald Trump never fails to stay from headlines. During a photo-call, none of the heads of government could bring themselves to speak to Mr Trump, preferring to huddle round Angela Merkel. The memorial includes a remnant of the fallen World Trade Center towers because it was then - after the 9/11 attacks - that North Atlantic Treaty Organisation first invoked Article 5 to take collective action. We are not confident Trump fully understands that.
Trump's remarks - paired with his conspicuous decision not to reiterate United States commitment to NATO's mutual defense provision, Article 5 - are likely to unsettle allies who had hoped to hear Trump assuage their concerns about his commitment to the historic alliance.
Melania Trump visits children's hospital in Rome
The first lady was initially caught on camera denying the commander-in-chief as they were walking together in Tel Aviv on Monday. The hospital, owned by the Catholic Church and founded in 1869, is the largest pediatric hospital and research center in Europe.
He added that Trump and his top officials had previously voiced Article 5 support, including "personally" with Stoltenberg at their meeting in the USA in April. As a candidate, he had expressed skepticism about it.
His remarks come several days after the release of his 2018 budget, which boosts military spending while cutting other programs in an attempt to eliminate the federal deficit.
KEITH: Jens Stoltenberg is NATO's secretary general.
Sean Spicer, the White House's press secretary, claimed that he had not seen the video of the shove when asked for a comment by reporters. "There's a lot of the relationship, whether its business or security, and it's not going away no matter who is president", says Ian Lesser of the German Marshall Foundation, an American public policy think tank.
"Twenty-three of the 28 member nations are still not paying what they should be paying for their defence", Trump said, standing by a piece of the wreckage of the Twin Towers. But sometimes when Trump talks about this commitment it's as if he's referring to dues payments, which it isn't.
"Many of these nations owe massive amounts of money from past years", Trump said yesterday in Brussels.