A Trump moment went viral for the wrong reason on Thursday as he and the leaders of 27 other NATO member countries assembled for a photo at the treaty organization's gleaming new Brussels, Belgium headquarters.

As Trump made his way through the group to take his position in the front row next to Secretary General Jens Stoltenberg, Montenegro's Prime Minister Duško Marković was in his way.

So Trump put his hand on Marković's upper arm and shoved him aside.

COMING THROUGH: Donald Trump saw Montenegro's prime minister in his way before a 'family photo' of NATO leaders, so he shoved him aside

The U.S. president tried to be nonchalant, but the resulting moment caught fire on Twitter

MADE IT: Trump ended up in the right spot, between Jens Stoltenberg and Theresa May, but not before he had crashed through the line

Montenegro is not yet a NATO country. Its membership becomes official on June 5.

The 'family photo' was planned with assigned positions for 31 people: the 28 heads of state and the Montenegrin, plus Stoltenberg, and the king and prime minister of Belgium, the host country.

Trump, Stoltenberg and the Belgians were set to be front-row center, with British Prime Minister Theresa May on Trump's other side.

Marković – the new guy – was placed in the back row on the far right end.

After the incident, he told reporters that the whole situation was harmless

'It didn't really register. I just saw reactions about it on social networks, he said. 'It is simply a harmless situation.'

Markovic added that it is 'natural that the president of the United States is in the front row.'

Trump was seen as a party pooper at the NATO summit, lecturing his fellow heads of state about their deadbeat nature and the need to secure their borders in the fight against terror.

The official seating chart put Trump (US) in the front row and Marković ('MON') in the corner. NATO protocol calls for alphabetical order with a few exceptions, including the U.S. having a place of honor in the front, next to the UK

MAKE WAY FOR THE AMERICAN: The other leaders seemed not to mind that Trump was barging in

CASUAL: Trump acted like nothing had happened after pushing his way to the front

'You have thousands and thousands of people pouring into our various countries and spreading throughout, and in many cases we have no idea who they are. We must be tough, we must be strong and we must be vigilant,' the president told them.

And he groused that 'NATO members must finally contribute their fair share and meet their financial obligations.'

'Twenty-three of the 28 member nations are still not paying what they should be paying,' he said, 'and what they are supposed to be paying, for their defense.'

'This is not fair to the people and taxpayers of the United States,' he said, 'and many of these nations owe massive amounts of money for past years.'

Trump had earlier put his weight behind his first handshake with France's new president, Emmanuel Macron, gripping and torquing his way on Thursday through the crucial moment in their budding relationship.

They shook hands for a full five seconds while camera shutters clicked, pumping their fists 16 times in a seeming battle of the phalanges.

Their knuckles turned white, their eyes met, their jaws clenched.

Trump ultimately released first, leaving Macron to hang on to his open hand.

Donald Trump and French President Emmanuel Macron pumped fists for a full five seconds on Thursday in Brussels as the two leaders seemed to be locked into a battle of the phalanges

In we go: Macron, France's youngest-ever president and youngest leader since Napoleon, had the upper hand as the grip began

Keep pumping: The grip and grin went on for a solid five seconds as Trump met Macron, the new French leader for the first time

French don't retreat this time: Trump appeared to be the first to try to end the handshake - but Macron kept gripping

That handshake in full: How the five seconds progressed was revealed in this composite photograph

The president and first lady Melania Trump greeted Macron at the U.S. ambassador's residence in the Belgian capital in advance of a NATO summit. He did not bring the French first lady to the meeting

Macron, the youngest French head of state since Napoleon, has held office for just 11 days.

But Trump, who is fond of winners and considers 'loser' to be the ultimate insult for murderous terrorists, seemed to give him his stamp of approval – moments before the younger president brought up global warming to jab him.

Just a month ago, he suggested that far-right French presidential candidate Marine Le Pen was the 'strongest' candidate 'on borders, and she's the strongest on what's been going on in France – a reference to terrorism.

Thursday he was firmly on Team Macron.

'It is my great honor to be with the newly elected president of France, who ran an incredible campaign and had a tremendous victory,' he said. 'All over the world they're talking about it.'

'We have a lot to discuss,' Trump added, 'including terrorism and other things. Congratulations. Great job.'

The two men did their best grip-and-grin at the Brussels residence of the U.S. ambassador to Belgium.