Joe Biden told the daughter of one of the hostages freed in a prisoner swap not to have “serious guys until you’re 30”.
Mr Biden broke from his speech on the historic release of Americans detained in Russia to pull the 12-year-old daughter of Aslu Kurmasheva, Miriam Butorin, to his side and ask the room to sing happy birthday to her.
“As you all know, we have a tradition in the Biden family. We sing happy birthday,” he said.
After the song, he had some advice for the girl, who turns 13 on Friday.
“And remember, no serious guys until you’re 30,” he said. “God love you.”
Mr Biden earlier confirmed that negotiations had resulted in the release of 16 people, including five Germans and seven Russian citizens.
They include Evan Gershkovich, a reporter for the Wall Street Journal who was arrested in 2023 on spying charges, Paul Whelan, a former US marine, Vladimir Kara-Murza, a journalist and Russian opposition figure, and Alsu Kurmasheva, a Russian-American reporter.
In exchange for 16 prisoners released from Russia, the US coordinated the release of eight Russian criminals including Vadim Krasikov, the “bicycle assassin” who killed a Georgian national in Berlin in 2019.
On Thursday Mr Biden hailed the deal as a “feat of diplomacy” that was a testament to having good allies who make “bold and brave decisions”.
The statement came almost two weeks after Mr Biden stepped back from the presidential race, following criticism of his age and mental acuity. He has been replaced at the top of the Democratic ticket by his vice president, Kamala Harris.