In an incident that officials feared could offend the prickly US President, the Prime Minister was filmed with world leaders whose chatter seemingly included remarks about Mr Trump’s unpredictable behaviour.
At one point in the conversation, picked up by a stray microphone, Canadian Prime Minister Justin Trudeau was heard saying: “He was late because he takes a 40-minute press conference off the top.”
Mr Trudeau later exclaimed: “You just watched his team’s jaws drop to the floor!”
Addressing the Nato summit this morning, Mr Johnson urged members “to strengthen the unity of purpose that has made Nato the greatest and most successful alliance in history”.
He pledged that Britain was “rock solid” in its commitment to the 70-year-old military alliance, calling it “a giant shield of solidarity that now protects 29 countries and nearly a billion people”.
Last night, Mr Johnson was standing with French President Emmanuel Macron, who has already clashed with Mr Trump over a tax on US tech giants, Mr Trudeau, whom the US President has been pressing to raise Canada’s contribution to Nato, Dutch Prime Minister Mark Rutte and Princess Anne.
They were chatting animatedly, apparently about how Mr Trump delayed proceedings by holding an impromptu press conference that lasted 48 minutes. As the leaders sipped drinks, Mr Johnson could be heard asking Mr Macron: “Is that why you were late?”
A video clip of the gossiping leaders went viral this morning, attracting four million views by the time Nato leaders gathered at a luxury hotel outside Watford for today’s summit to mark the alliance’s 70th anniversary. Mr Johnson was described as “smirking” in an online report about the viral video for US broadcaster Fox News, which Mr Trump is known to follow.
Downing Street quickly made clear that Mr Johnson had not been involved in any laughing about any disruption caused by the US President’s press conference, which was held at the American ambassador’s residence in Regent’s Park yesterday morning.
A senior source said: “The Prime Minister was hosting and engaging with world leaders. It is others that were having the conversations and Boris certainly was not leading, as can be seen from the clip.
“You did not see any commentary from him except for an innocent question as to why one was late.”
Mr Trump looked stony-faced when he arrived at the summit this morning in his helicopter, Marine One.
He posed for handshakes and photographs with host Mr Johnson and Nato secretary general Jens Stoltenberg, then walked in the wrong direction and had to be shown the right way by the Prime Minister.
The viral video and the fear of an angry outburst by the US leader was a huge setback to Mr Johnson’s hopes that the summit and his unpredictable VIP guest would fade into the background rather than overshadow election campaigning.
The Prime Minister and US President held a bilateral meeting at No 10 last night — but unusually did not issue pictures of the traditional handshake or allow the media to film them sitting down together.
Arriving for the summit this morning, Mr Johnson said the post-war alliance remained “rock solid” despite disagreements, notably between Mr Trump and Mr Macron.
“Clearly it is very important that the alliance stays together, but there is far, far more that unites us than divides us,” said Mr Johnson.
Addressing the Nato leaders, Mr Johnson continued: “History shows that peace cannot be taken for granted, and even as we celebrate this anniversary we must ensure that our deeds match our words.
“The atrocity in London last Friday shows why we must work together to combat terrorism and the vital importance of Nato’s missions to counter this threat.”
He said he and Mr Trump had enjoyed a “very good” meeting last night.
“We discussed the future of Nato, we discussed what is going on in Syria and various other matters,” he said.
The PM is today scheduled to meet German Chancellor Angela Merkel and the prime minsters of Denmark and Italy, and will also participate in a working lunch with representatives of Britain, Estonia, Greece, Latvia, Poland, Romania, Lithuania and Bulgaria.
Mr Trump has frequently appeared sensitive about the US being mocked on the world stage. He repeatedly claimed during his 2016 presidential election campaign: “The world is laughing at us.”
At the United Nations general assembly last year, where Mr Trump boasted that his administration had “accomplished more than almost any administration in the history of our country”, there was a ripple of laughter in the hall, prompting the President to claim later: “They weren’t laughing at me, they were laughing with me.”
A year earlier, when he signalled that he would pull America out of the Paris agreement on climate change, Mr Trump hit out, saying: “We don’t want other leaders and other countries laughing at us any more. And they won’t be. They won’t be.”
Despite Downing Street’s hopes that Mr Trump would stay out of the UK general election, he waded in yesterday by praising Mr Johnson as “capable”, backing Brexit and claiming the US would not want to buy up the NHS even if it was served up “on a silver platter”.
Mr Macron’s has commented that Nato is “brain-dead”, a remark described as “very nasty”, by Mr Trump.