Right before the Russian president Vladimir Putin and Saudi Crown Prince Mohammed bin Salman took their seats next to each other, cameras captured them saying hello, grinning widely, and engaging in quite the shake.
World leaders have condemned the incident, with Canada, France and Germany imposing sanctions on Saudi Arabia and UK Prime Minister Theresa May vowing to question the Crown Prince about it at the G20.
Trump is one of the only US officials who has refused to criticize the Saudi crown prince and the Russian president for violating human rights and attacking their neighbors.
Britain has come under pressure to cease arms sales to Saudi Arabia because of the high death toll in air raids by the Western-backed Saudi-led coalition in Yemen.
MbS: "Don't worry" Macron: "I do worry".
Later in the one-minute clip Macron says: "You never listen to me" and the crown prince replies: "I will listen, of course".
A cryptic exchange between the pair on Friday was caught on video and shared by the English-language Saudi Gazette.
"I am a man of my word", Macron adds.
Putin high-fives MBS at G20, but did he shake Trump's hand?
Trump, who was seen passing by MBS and Putin without interacting with either, is not expected to meet with the crown prince.
Russian forces seized the vessels and their crew and Moscow's refusal to return them was the ostensible reason Donald Trump offered for his decision to cancel a lengthy bilateral meeting with Putin that had been planned for Friday morning.
"They exchanged pleasantries at the leaders' session as he did with almost every leader in attendance", the White House official said on Friday.