Bremmer said that at the end of the summit, Merkel and Trudeau were pressing Trump to sign the joint communiqué, a statement expressing common diplomatic goals and traditionally signed by all parties at G7 summits.

"Trump was sitting there with his arms crossed, clearly not liking the fact that he felt like they were ganging up on him. He eventually agreed; he said OK, he'll sign it," Bremmer said. "At that point, he stood up, he put his hand in his pocket — his suit jacket pocket — and he took two Starburst candies out, threw them on the table, and said to Merkel: 'Here, Angela. Don't say I never give you anything.'"