Washington(CNN) Chief of Staff John Kelly told President Donald Trump that President Barack Obama never called him after his son's death prior to Trump raising the issue in a Tuesday radio interview, multiple White House officials told CNN.

But, according to these sources, Kelly never thought the President would use that information publicly.

Kelly and much of the White House were caught off-guard by Trump's comments, one official said, struck by how the President took a story Kelly has tried to keep private -- the death of his son -- and used it to defend his handling of four soldiers killed in Niger.

Trump, in defense of his own previous claim that Obama didn't call the loved ones of fallen soldiers, floated the idea Tuesday that reporters ask Kelly, a retired general, whether Obama called him after his son died in Afghanistan.

"As far as other presidents, I don't know, you could ask Gen. Kelly, did he get a call from Obama? I don't know what Obama's policy was," Trump said during a Fox News radio interview.

Kelly's son Robert died when he stepped on a landmine in Afghanistan in 2010. Kelly, a retired four-star Marine general, was a lieutenant general at the time.

White House press secretary Sarah Sanders said Wednesday that Kelly might not have been specifically aware Trump was going to raise his son's death during an interview, but slammed the media for, in her words, politicizing Robert Kelly's death.

"I know he has spoken to Gen. Kelly multiple times yesterday and today. I am not sure if he knew of that specific comment, but they had certainly spoken about it," Sanders said. "And he is aware and they have spoken several times since then."

But Kelly "is disgusted by the way this has been politicized and that the focus has come on the process, and not the fact that American lives were lost. I think he is disgusted and frustrated by that," Sanders said, pointing the finger at media coverage.

"If he has any anger, it is towards that," she said.

After Trump made the comment on Tuesday, multiple White House officials told CNN that Obama did not call Kelly when his son was killed.

CNN asked the White House to talk to Kelly about this issue, but they declined to make him available. Kelly did not respond to a direct request from comment from CNN and the White House declined to make any statement on the record.

Kelly, the highest-ranking military official to lose a child in Iraq or Afghanistan, has tried to keep his son's death private.

The Washington Post, in a 2011 profile of Kelly, reported that the general asked a Marine Corps officer not to mention his son's death when he was introduced at a St. Louis event days after his son was killed.

Kelly, who is regularly seen next to the President at events, was noticeably absent from Trump's events on Tuesday afternoon after he made his comments about the retired Marine four-star general's son. Kelly, though, was sitting across from Trump during a Wednesday meeting on tax reform.

Trump waited nearly two weeks to call the families of four soldiers killed in Niger earlier this month and never used his very active Twitter account to mark the deadliest combat incident since he took office. Sanders said Tuesday that Trump had spoken with "all four of the families of those who were killed in action in Niger."