Donald Trump on Wednesday sniped at Canadian Prime Minister Justin Trudeau, one of the world leaders caught sniping at the U.S. president during a reception at Buckingham Palace.

'He's two-faced,' he said of Trudeau, complaining that Canada is delinquent in spending 2 per cent of its GDP on defense—something members of the alliance all pledge to do.

And then in a hot-mic moment of his own later in the afternoon, Trump was overheard saying after speaking to Italy's prime minister: 'That was funny when I said that guy was two-faced.'

The remark was heard by a radio reporter who still had access to sound from the room after journalists were told to leave.

Trump canceled his final press conference at the NATO summit on Wednesday after Trudeau and two other world leaders - Emmanuel Macron of France and Boris Johnson of Britain - were caught on their own hot mic roasting him, with Princess Anne, the Queen's daughter, nodding along.

The president had spoken with reporters for more than two hours since arriving in London on Monday and claimed he had answered enough questions.

He left the NATO summit on schedule, returning to the U.S. on Air Force One with First Lady Melania Trump, who had spent the day with schoolchildren in East London.

He told reporters during a brief press availability Wednesday afternoon in London that '[if] you're demanding a press conference we'll do one, but I think we've answered plenty of questions.'

Another hot-mic moment: After he ended a press availability with Italy's prime minister Giuseppe Conte, Trump was heard boasting about his body slam of Justin Trudeau saying: 'That was funny.'

After Trump canceled the event, work crews dismantled the podium

Justin Trudeau, center, Emmanuel Macron, second right, and Boris Johnson, right, have all been caught on a hot mic at the Buckingham Palace NATO reception appearing to gossip about Donald Trump and an apparent impromptu lengthy press conference

Trump's cancelation means he wasn't on TV during Wednesday morning's must-watch impeachment hearings, being held by the House Judiciary Committee

'I'll cancel the news conference. I've done so many,' he added an hour later at a planned luncheon, adding: 'I think that’s enough.'

And in a tweet, he announced: 'When today’s meetings are over, I will be heading back to Washington. We won't be doing a press conference at the close of NATO because we did so many over the past two days. Safe travels to all!'

Trump's cancelation means he won't be on TV in the now-customary attempt to pre-empt Wednesday morning's must-watch impeachment hearings, being held by the House Judiciary Committee.

Trudeau, French President Emmanuel Macron, UK Prime Minister Boris Johnson, and Dutch Prime Minister Mark Rutte were caught at a Buckingham Palace NATO reception Tuesday night, appearing to gossip about the length of Trump's unexpectedly long press briefings.

In a clip being widely shared online the three world leaders seem to be discussing why the French President was late during the London summit. Princess Anne also appears to be in the discussion, left, but it is unclear if or how she responds

Trump is pictured this morning getting off Marine One at The Grove, Watford, Hertfordshire, where the NATO summit will take place today

In a clip, the three world leaders seem to be discussing why the French leader was late during the London summit, held to mark the alliance's 70th anniversary. The UK's Princess Anne also appears to be involved in the discussion.

None of the men mention Trump by name but Rutte is heard joking with Macron about the 'fake news media,' with Trudeau appearing to refer to the U.S. president's talks with the press on Tuesday.

Trump had spoken at length to reporters in the afternoon after an awkward press availability with Macron, following on from an earlier and equally lengthy morning press chat after a sit-down with NATO president Jens Stoltenberg.

In the clip, Johnson asks: 'Is that why you were late?' as he stoops down and chuckles in disbelief, before Trudeau, swigging from his drink, shoots back: 'He was late because he takes a 40 minute press conference off the top.'

The video then cuts to a later clip, which is without context, and sees Macron pointing furiously before Mr Rutte exclaims 'fake news media' and Trudeau adds: 'You just watched his team's jaws drop to the floor.' He then motions as if his jaw is dropping. However, it is not known if Trump is the focus of that comment as the video has been edited.

The US President has touched down in Marine One as he and other world leaders gear up for today's NATO summit in Hertfordshire.

The Queen is pictured alongside First Lady Melania Trump at Buckingham Palace for the 70th anniversary of NATO last night

Her Majesty was seen surrounded by world leaders and their partners at her reception for NATO at Buckingham Palace last night

The Queen smiled as she greeted Melania and her husband, with Prince Charles and Camilla on her left side and Mr. Jens Stoltenberg, Nato Secretary General on her right

All smiles: Back row, (from left) Xavier Bettel, Prime Minister of Luxembourg; Egils Levits, President of Latvia; Gitanas Nauseda, President of Lithuania; Dusko Markovic, Prime Minister of Montenegro; Erna Solberg, Prime Minister of Norway; Mark Rutte, Prime Minister of Netherlands; Zuzana Caputova, President of Slovakia; Andrzej Duda, President of Poland; Antonio Costa, Prime Minister of Portugal; Klaus Iohannis, President of Romania; Marjan Sarec, Prime Minister of Slovenia, (middle row from left) Edi Rama, Prime Minister of Albania; Zoran Zaev, Prime Minister of North Macedonia; Mette Frederiksen, Prime Minister of Denmark; Juri Ratas, Prime Minister of Estonia; Emmanuel Macron, President of France; Angela Merkel, President of Germany; Kyriakos Mitsotakis, Prime Minister of Greece; Viktor Orban, Prime Minister of Hungary; Katrin Jakobsdottir, Prime Minister of Iceland; Giuseppe Conte, Prime Minister of Italy; Andrej Plenkovic, Prime Minister of Croatia, (seated from left) Sophie Wilmas, Prime Minister of Belgium; Rumen Radev, President of Bulgaria; Donald Trump, President of United States; Prince Charles, Prince of Wales; Jens Stoltenberg, Nato Secretary General; Queen Elizabeth II; Boris Johnson, Prime Minister of the United Kingdom; Justin Trudeau, Prime Minister of Canada; Pedro Sanchez, Acting Prime Minister of Spain; Recep Tayyip Erdogan, President of Turkey; Milos Zeman, President of the Czech Republic pose for a group photo with the Queen at the Nato

The clip originated from a video feed shared with news agencies at the NATO meeting. It was first shared by the Canadian Broadcasting Corporation. Pictures from the event also show Princess Anne talking to Johnson and Trudeau.

The world leaders were all in London Tuesday for a summit to mark the alliance's 70th anniversary.

Boris Johnson's conversation with Emmanuel Macron, Justin Trudeau, Mark Rutte and Princess Anne in full Boris Johnson: Is that why you were late? Justin Trudeau: He was late because he takes a 40 minute press conference off the top. Inaudible conversation Justin Trudeau: Oh yeah, yeah yeah, he announced… Emmanuel Macron speaks with his back turned to the camera Mark Rutte: Fake news media! Macron touches Rutte's arm in agreement Clip jumps to another point in the conversation Princess Anne speaks with her face hidden from the camera Justin Trudeau: You just watched his team's jaws drop to the floor. Advertisement

Trump had earlier needled Macron about accepting captured ISIS fighters – offering to 'give them to you' - during the heated and lengthy joint news conference.

Afterward he went to Clarence House along with First Lady Melania for tea with Prince Charles and Camilla. The president and his wife arrived 40 minutes late to the meeting - the delay which Trudeau appears to be referencing.

Following a reception with the Queen at Buckingham Palace, Trump and Melania made their way to Downing Street where they were kept waiting for 10 minutes by Boris.

Johnson eventually welcomed the pair inside, but stood over the threshold rather than posing for pictures on the steps as is usually the case - keen to minimise his perceived closeness to Trump during an election where Labour has repeatedly attacked him for it.

They held a sit-down meeting of their own, but again, no photojournalists were permitted.

Trump's Macron meeting was one of three bilateral sit-downs where he spoke and fielded questions from reporters for a total of two hours, flooding the media landscape on a week when House Democrats are proceeding with impeachment at home.

The president earlier took a dig at Macron for France and other European nations being reluctant to accept nationals from their own countries who joined the fight alongside ISIS terrorists.

Trump turned to his counterpart and asked: 'Would you like some nice ISIS fighters? I could give them to you.'

The moment came hours after Trump had blasted Macron for previous comments that NATO was suffering 'brain death'.

Macron in an interview had said NATO was suffering 'brain death,' highlighted a split over Turkey, and said the treaty alliance must remained unified.

'You just can't go around making statements like that against NATO. It's very disrespectful,' Trump groused at the start of two days of meeting with world leaders, including Macron.

The Princess Royal, right, talks to Prime Minister Boris Johnson, center, and Canadian Prime Minister Justin Trudeau, left, during a reception at Buckingham Palace, London, as NATO leaders attend to mark 70 years of the alliance

The Prince of Wales and the Duchess of Cornwall, right, meets Trump and wife Melania at Clarence House on Tuesday. A timeline of the US president's day at the NATO summit shows Trump first met with Macron on Tuesday at 2pm GMT. At 2:20pm the two opened their meeting to the press. By 3:30pm Trump held a bilateral meeting with Trudeau

FLOTUS and POTUS (left) seemed to be having a grand old time as they laughed and joked with the Prince of Wales (right)

A smile for the cameras: Melania is pictured beaming in her striking yellow ensemble with Trump slightly in front of her

The Trumps are pictured alongside 'The Beast' as they arrived at Downing Street for the second reception last night

Trump and First Lady Melania are pictured outside No10 Downing Street for a second reception hosted by Boris Johnson last night

Over and out: Donald Trump waves goodnight to crowds as he leaves last night's Downing Street NATO reception

Trump called it a 'very, very nasty statement to essentially 28, including them, 28 countries' that are part of NATO. He spoke at his first bilateral meeting, with NATO Secretary General Jens Stoltenberg.

Humiliation for Jeremy Corbyn as his Palace confrontation with Donald Trump over the NHS falls flat and he is kept apart from him Jeremy Corbyn has suffered fresh humiliation by being kept apart from Donald Trump at Tuesday night's Buckingham Palace reception after vowing to confront the US President over the sanctity of the NHS. The Labour leader said he would warn the President that 'public services are not for sale' at a gathering of Nato leaders and Royals hosted by the Queen. But in an embarrassing setback, the left-winger never got the chance to speak with Mr Trump and follow through on his promise, which was derided by one cabinet minister as a 'desperate stunt'. It was the second blow Mr Corbyn has been dealt yesterday after the President killed his main election attack line by flatly dismissing the idea he wants a post-Brexit trade deal to open the health service to American companies and push up drugs prices. Advertisement

'I heard that President Macron said that NATO was brain dead,' Trump said, in a long back-and-forth with reporters. 'I think that is very insulting towards a lot of different forces,' he added.

Trump rapped Macron for his words and ripped the French economy while also brandishing U.S. economic power in a growing trade spat with Paris.

'It's a tough statement though when you make a statement like that,' Trump complained.

'Nobody needs NATO more than France. You just look back over the long period of time,' Trump said. 'Frankly the one that benefits really the least is the United States.'

'We benefit the least. We're helping Europe. Europe unites when they go against a common foe ... That may or may not be a foe,' Trump said, in a presumed reference to Russia.

Trump said of France: 'It's a very tough statement to make when you have such difficulty in France.

'They've had a very rough year,' and brought up the 'yellow vest' protests, said France had a high unemployment rate, and said it was 'not doing well economically.

He referenced new tariff escalations being recommended by U.S. trade representative Robert Lighthizer Monday. They include new tariffs on French champagne, wine, cheese, and other products totaling $2.4 billion.

'We're doing their wines and everything else,' Trump said. 'You just can't go around making statements like that against NATO. It's very disrespectful.'

By the evening, Trump offered the French president a ride in the 'Beast'.

How do you do? The President and the First Lady arriving earlier yesterday evening (left) as Melania exchanged greetings with Prince Charles (centre) and Camilla (right)

French President Emmanuel Macron greets US first lady Melania Trump as U.S. President Donald Trump looks on as they arrive for an evening reception for Nato leaders hosted by Prime Minister Boris Johnson at 10 Downing Street

Kate Middleton (above) looked stunning yesterday evening as she wore a green dress and wore her hair in loose waves at the reception

The Queen beamed a radiant smile (centre) after cruel trolls speculated over her death on social media earlier this week

Canadian PM Justin Trudeau chats with Camilla, Duchess of Cornwall at Buckingham Palace's NATO reception last night

Guten abend: Boris Johnson greets his German counterpart Angela Merkel as the NATO reception kicks off at Buckingham Palace

Chancellor Merkel was also seen chatting to Princess Anne as leaders mixed with the royals at Buckingham Palace last night

Trump also teed off on France's digital services tax which he said is unfair to U.S. tech giants like Facebook, Google, and Twitter.

'I'm not going to let people take advantage of American companies. Because if anybody's going to take advantage of American companies, it's going to be us,' Trump said.

Trump made his remark about ISIS after pressing France to accept the return of more of its countrymen and women, and pledging they were currently being held under 'lock and key.'

'We have a tremendous amount of captured fighters, ISIS fighters over in Syria. And they are all under lock and key but many are from France, many from Germany and many are from the U.K.

'They're mostly from Europe. And some of the countries are agreeing. I have not spoken to the president about that. Would you like some nice ISIS fighters? I can give them to you. You can take every one you want,' Trump quipped.

That drew a caution from Macron.

'Let's be serious,' the French leader scolded, before outlining his own position. 'It is true you have a current fighters coming from Europe. But it's a minority problem of the overall problem we have. And I think the number one priority because it is not yet finished is to get rid of ISIS,' Macron lectured, as Trump listened to a translation of his remarks.

US President Donald Trump, right, and France's President Emmanuel Macron, left, react as they talk during their meeting at Winfield House on Tuesday

Prime Minister Justin Trudeau meets U.S. President Donald Trump at Winfield House

Trump has previously declared victory over ISIS, only to say a contingent of U.S. forces would remain.

'And it is not done, I'm sorry to say that,' Macron told him. 'Your number one problem are not the foreign fighters, it is the ISIS fighters in the region and you have more and more of these fighters due to the situation today,' he said.

The comment drew a counter from Trump. 'It's why he is a great politician. That was one of the greatest non-answers I've ever heard and that's okay,' Trump said.

'France has taken back some fighters, actually. We have a lot of fighters, he said, before noting that U.S. and allied forces captured '100 per cent of the caliphate.

During a separate meeting with Trudeau, Trump called Canada 'slightly delinquent,' even as he went after other nations for paying less than a 2 percent of GDP commitment on defense.

Prime Minister Boris Johnson (right) talked to guests during a reception at Buckingham Palace, London, as Nato leaders gathered to mark 70 years of the alliance

Prime Minister of Denmark Mette Frederiksen arrived earlier yesterday evening at a reception for NATO leaders at Buckingham Palace

He also singled out Germany, whose NATO contributions have hovered around 1 per cent. ''They would owe us money. You're talking about - really you're talking about trillions of dollars,' Trump said, bringing up compounded past years of sub-2 per cent spending.

'Nobody has ever brought that up. They just keep talking about the present,' he said.

It was after the reception with the Queen at Buckingham Palace, Trump offered Macron a ride in the Beast, his famous Cadillac equipped with armor, bullet-proof glass, and run-flat tires, en route to 10 Downing Street for a reception hosted by British Prime Minister Boris Johnson.

And it was there that Macron was pictured warmly clasping First Lady Melania Trump's hand.

Macron made up for the chill in the air and in the day's earlier encounters with the warm handshake he gave to the first lady, who wore a yellow Valentino cape to the event. Trump was pictured looking on during the greeting.