When US President Donald Trump met Canadian Prime Minister Justin Trudeau today, many were watching for one thing - the handshake.
Trump is known for his aggressive, dominant handshake style, in which he grips the other and pulls the strongly toward himself.
Psychologists say this can be interpreted as a power play and a sign of wanting to put the other person off balance.
But Trudeau was no pushover - he held his ground and held Donald's hand firm.