President Donald Trump, a man who talks so often about the importance of being treated respectfully, will not have enjoyed the spontaneous giggles erupting from diplomats and heads of state as he addressed the UN.
"Quite something," one senior diplomat said to me.
But from an observer's perspective, it was a fantastically revealing moment – laying bare the disconnect between Trump and the rest of the world.
His inflated rhetoric, usually accepted by US politicians and Trump fans well-used to his exaggerated style, crashed headlong in to reality.
The audience was simply not able to entertain his claim that the Trump administration had made more progress than probably any other in history.
Not a good start.
But in an interesting way that moment actually set the tone for the rest of the speech, in which Mr Trump, purposefully this time, only widened the gap between himself and his audience as the address went on.
For this was a speech singularly at odds with the very institution of the United Nations, and the post-war international order it nurtures and protects.
Mr Trump criticised a shopping list of multilateral organisations and agreements; the Iran deal, the human rights council, the international criminal court, OPEC, multilateral trade agreements, migration compacts and foreign aid arrangements.
The US president urged the world's nations to join the US in isolating Iran, whose leaders he said "sow chaos, death and destruction".
Mr Trump said he had launched an "economic pressure" campaign to deny the country the money it needs to advance a "bloody agenda" of havoc and slaughter in Syria and Yemen.
On the international criminal court, Mr Trump said: "As far as America is concerned the ICC has no jurisdiction, no legitimacy and no authority."
Despite requests, I have no plans to meet Iranian President Hassan Rouhani. Maybe someday in the future. I am sure he is an absolutely lovely man!
— Donald J. Trump (@realDonaldTrump) September 25, 2018
The president went on to accuse OPEC, an intergovernmental organisation of 15 countries, of "ripping off the world".
The nations account for an estimated 44% of global oil production and 81.5% of the world's "proven" oil reserves.
Mr Trump said: "The United States stands ready to export our abundant affordable supply of oil, clean coal, and natural gas.
"OPEC and OPEC nations are, as usual, ripping off the rest of the world, and I don't like it.
"Nobody should like it."
Mr Trump later praised himself and North Korea for making limited progress over denuclearisation,
He noted that "missiles and rockets are no longer flying" from the country and threatening its neighbours.
Mr Trump met Mr Kim in Singapore in June and the White House is working toward scheduling a second summit.
The US president also heaped praise on all those countries who place their own interests above all else.
This, he declared, should be the ultimate ambition; "a doctrine of patriotism" over global governance.
Peace through strength.
Security without apology.
Only through these ideals, he argued, will individual nations reach their full potential.
It was classic Trump – populist, nationalist, and entirely focused on voters at home.
And despite the initial mirth, it will have been a disturbing message for the assembled diplomats and heads of state.
Western leaders like Theresa May and Emmanuel Macron are here to argue in favour of multilateralism over the blanket promotion of national interests.
There is increasingly little common ground between the unpredictable Trump and America's traditional close friends.
In the short term he may enjoy the disruption that comes with that.
But on the other side are huddles of weary diplomats determined, if possible, to carry on without him.
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