It also appeared to be an opportunity for the first lady — who, like many before her, has positioned her identity as a mother as a central one — to use her office to highlight the reality of the war in Ukraine: As many as 90 percent of the people who have been displaced are women and children, according to United Nations figures.
Ms. Zelenska, 44, was among the first to be displaced when the war began.
In a speech only days after the first Russian missiles fell on Kyiv, Ukraine’s capital, Mr. Zelensky said he knew he was the first target for assassination in case of an occupation. His wife and children, Oleksandra, 17, and Kyrylo, 9, he said, are “target No. 2.” Since then, her whereabouts has been kept private.
A first lady who once focused on issues of female empowerment, literacy and culture in Ukraine, Ms. Zelenska, like her husband, now spends much of her time trying to bring the world’s attention to what is happening in her country. She wrote to Dr. Biden in April, expressing her concerns for the emotional well-being for the citizens of Ukraine, Mr. LaRosa said.
Her concerns appeared to have been received by Dr. Biden, who spent much of her time in front of the cameras quizzing humanitarian organization workers on their capacity to support women and children who had endured the trauma of war.
At stop after stop, in Romania and in Slovakia and later in Ukraine, Dr. Biden talked to children who had circles of exhaustion under their eyes and mothers who were on the verge of tears. She stood among bottles of baby formula and well-worn toys and asked whether volunteers had what they needed.
Allida Black, a historian who studies first ladies, said Dr. Biden’s work was in the tradition of other first ladies who had traveled oversees to witness the “personification of pain,” hearing stories of trauma and war, all while staying within the limits of an unelected role within the administration.
“There’s real finesse to this,” said Dr. Black, who has been an adviser to Hillary Clinton. “Because you’ve got to carry all of those memories with you. It’s hard work.”