But several families said they had not heard from the president.

“I was told I would receive a call and I never did,” said Whitney Hunter, whose husband, Sgt. Jonathon Hunter, was killed in Afghanistan in August. An Army official who had spoken to the White House had relayed to her that she should expect a call over the summer. By Wednesday, Ms. Hunter said, she had not even received a letter from Mr. Trump.

“It’s not a necessity, but it’s just good human nature for condolences to be shared,” said Ms. Hunter, who noted that Vice President Mike Pence had met with her at an Air Force base in Delaware. “Even though it is the president and I know there are pressing world issues, my husband died for our country.”

For families of the fallen, meetings that do happen can be a blur, especially if they are soon after the death of their loved one.

Dianne G. Johnson, whose husband was killed during a 1980 mission to rescue American hostages in Iran, said she believed that President Jimmy Carter had simply expressed his grief during a meeting at Arlington National Cemetery.

“At that particular point, there wasn’t a whole lot I could talk about,” Ms. Johnson said from her home in Georgia, where officials dedicated a bridge this month in honor of her husband, Staff Sgt. Dewey Johnson of the Marines.

“It was very emotional,” she said of her meeting with Mr. Carter. “I think I said thank you.”

She later visited the White House, where she met President Ronald Reagan and the elder George Bush, then vice president. Mr. Reagan, she said, also shared his sorrow. But Mr. Bush, she recalled, had a personal touch.

“He said he was sorry, and he said he and I had something in common,” she said. “And I thought, ‘Oh dear, what is this?’ He said, ‘You and I cry when they play the national anthem.’”