There have been many people to meet and greet, and with the eyes of the world watching too. And so it has not gone unnoticed that Trump's handshaking technique is, well, unusual.

The President has a propensity to yank the hand of his unsuspecting victim towards him - sometimes multiple times - vigorously jerk the hand up and down, and often pat it a couple of times with his other hand.

Some people have suggested that Trump's aggressive handshake technique is a way for him to try and exert dominance and authority over the other person involved - he wants to make it clear he's the one in control.

We saw this with Japanese Prime Minister Shinzo Abe and Judge Neil Gorsuch.

Canadian Prime Minister Justin Trudeau, however, didn't let Trump go down his usual route when they met on Monday - Trudeau put his hand on Trump's upper arm to stop himself being pulled in by the President.

We already know Trump avoids holding his wife's hand because he wants to seem more 'alpha', and body language expert Darren Stanton believes the same is behind his handshaking technique.

"For President Trump, it's all about the assertion of power and control," he told The Independent. "Trump is saying 'this is my space, my time, you are the guest, my house rules apply."

Stanton says Trump's style is called a "bone-crusher handshake" which involves completely engulfing the other person's hand in your own. "Its purpose is to convey power and confidence to the other person, as if to say, 'Hey I'm in charge, don't mess with me.'"

The disregard of personal space is also worth noticing - as Trump pulls the other person into his personal space, Stanton says this is his way of working out whether they're going to be compliant or not.