The White House chief of staff has launched an impassioned attack on a "selfish" congresswoman who said President Trump made a war widow cry.
Sgt La David Johnson
Gen Kelly also said he did not receive a call from President Barack Obama when his son died in Afghanistan in 2010.
Sgt Johnson was one of four killed in Niger by Islamist militants this month.
The chief of staff, a former Marine Corp general, said in the White House briefing room that Representative Frederica Wilson was "an empty barrel".
The Florida Democrat said on Wednesday that she overheard Mr Trump telling bereaved Myeshia Johnson of her slain husband: "He knew what he was signing up for, but I guess it hurts anyway."
President Trump denies making the remark.
Gen Kelly said he was so "stunned" by Ms Wilson's attack that he spent more than an hour walking among soldiers' graves at Arlington National Cemetery, just outside Washington.
The chief of staff said he had advised the president not to call the loved ones of the four American servicemen killed in Niger, telling him: "There's nothing you can do to lighten the burden on these families."
Gen Kelly described such a task as "the most difficult thing you can imagine".
"There is no perfect way to make that phone call," he added.
He also discussed the death of his own son, Robert Kelly, a 29-year-old Marine first lieutenant who died when he stepped on an Afghan landmine.
Gen Kelly said: "He [President Trump] asked me about previous presidents. And I said, 'I can tell you that President Obama, who was my commander-in-chief when I was on active duty, did not call my family.'
"That was not a criticism. That was just to simply say, I don't believe that President Obama called.
That's not a negative thing.
"I don't believe President Bush called in all cases. I don't believe any president, particularly when the casualty rates are very, very high, that presidents call."