Trump then confidently adjusts his jacket. -European relations since Trump took office. "And many of these nations owe massive amounts of money from past years and not paying in those past years", he said yet again.
Mr. Trump is not the only US president to urge allies to increase military spending, but he is the first to not explicitly commit to NATO's collective defense clause: "An attack on one is an attack on all".
"We should recognize that with these chronic underpayments and growing threats, even two percent of GDP is insufficient to close the gaps in modernizing readiness and the size of forces", he continued. Trump stood beside a section of wrenched steel from the downed World Trade Center Towers, a relic North Atlantic Treaty Organisation calls the "Article V artifact", to signify that post-9/11 invocation of the North Atlantic Treaty Organisation charter's article holding that an attack on any one member would be considered an attack on all.
Mr Trump's comments may disappoint some officials in Europe who had hoped that the USA president would offer a public endorsement of Nato's mutual-defense doctrine at the ceremony that honored Article 5, as the provision is known. Trump had suggested this could depend on when allies paid their dues. The former Polish prime minister received the USA president for the first time in Brussels. "It just increases a lot of the doubts and fears and concerns our allies have had", he told Foreign Policy. Trump did mention Article 5 in his speech - it was unavoidable, given the memorial he was unveiling.
The address created one of several awkward moments, as several leaders including Macron and German Chancellor Angela Merkel could be seen grimacing and rolling their eyes. "Major mistake", former USA ambassador to NATO Nicholas Burns wrote on Twitter.
The deployment of US troops to Poland and the Baltics have been central to an expansion of NATO's presence in eastern Europe to levels unprecedented since the Cold War. How do those remarks constitute any waffling on USA commitments?More news: Trump's North Atlantic Treaty Organisation debut does little to assure allies
What he said at the gathering today is unlikely to provide those allies much reassurance.
Separately, Trump vowed to crack down on leaks that led British police to withhold information from the United States about the investigation into this week's concert bombing.
The former Yugoslav republic is pegged to become NATO's 29th member next month.
Mr Smith also slammed the enormous $110-billion (£85bn) arms supply deal that Mr Trump sealed with al-Qaida and Isis backer Saudi Arabia at the weekend.
Another Democrat, Rep. Jared Huffman of California, more subtly critiqued Trump's decorum at the summit, retweeting a video showing Trump pushing aside another leader.