French President Emmanuel Macron has opened up on the excruciatingly long handshake he shared with Donald Trump last week, admitting that the greeting was every bit the power struggle that it seemed.

Footage of their handshake at the NATO summit in Brussels went viral last week. Both of their knuckles had turned white by the end of the marathon seven-second grip.

On Sunday, newly-elected Macron said the forcefulness was no mistake.

'You have to show you won't make little concessions, even symbolic ones. It's not the be-all-and-end-all... but a moment of truth.

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France's Emmanuel Macron said he intentionally held on to Trump's handshake in Brussels last week to assert his authority

'I don't miss a thing, that's how you get respect,' the 39-year-old told The Associated Press.

The pair were addressing a group of photographers and journalists when they shook hands on Thursday.

Trump, still in the midst of his first overseas tour, congratulated Macron on his recent election victory.

'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,' he said, extending his hand out to take Macron's.

Tense: Macron said the handshake was a symbolic gesture to prove that he 'won't make concessions' as France's new leader

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

First Ladies Brigitte Trogneaux and Melania Trump had their own stand-off in the style stakes when they posed at the Magritte museum in Brussels

After several seconds, neither president had let go.

They stared one another squarely in the eye, nodding politely as their knuckles grew paler before President Trump withdrew. It was the first time the pair had met in person.

Their respective first ladies were caught in a similar stand-off when they posed side-by-side at the Magritte Museum.

Melania beamed in her nude leather skirt suit and snakeskin heels, her eyes lighting up for the cameras as she stood out in a line-up of NATO wives.

France's first lady Brigitte Trogneux was elegant in a black Louis Vuitton dress and Mary-Janes but couldn't quite muster the same enthusiasm as her American counterpart, offering just the slightest of smiles for the gathered press.

Macron (pictured with his wife at the National Cup Final on Saturday) was elected on May 14