The moment followed Trump's speech at the headquarters' opening, during which he slammed US allies for not spending enough on defence before an uncomfortable-looking audience of fellow heads of state.
He berated allies for "chronic underpayments" on defence spending in the face of aggressions from terrorism to "this is not fair to the people and taxpayers of the United States".
"And many of these nations owe massive amounts of money from past years and not paying in those past years," he said yet again. (Of course, as Trump has had explained to him countless times, countries don't pay any dues to Nato, as they do to organisations like the UN, so it's unclear what he is talking about.)