Kelly, in an unexpected and emotional appearance in the White House briefing room, invoked the death of his own son, killed in Afghanistan in 2010, as he lashed out at Rep. Frederica Wilson of Florida, who earlier this week said that President Donald Trump had been disrespectful in his condolence call to the family of Sgt. La David Johnson, who was killed during an ambush in Niger.
Kelly, speaking slowly and forcefully, said he was "heartbroken" that Wilson overheard the conversation and used it to attack the president.
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"I was stunned when I came to work yesterday and brokenhearted at what I saw a member of Congress doing," Kelly said. "It stuns me. And I thought at least that was sacred."
Kelly absolved Trump of blame, suggesting that the president did the best he could in one of the most challenging aspects of his job.
"If you're not in the family, if you have never worn the uniform, if you have never been in combat, you can't imagine how to make that phone call," Kelly said.
Trump - who has frequently struggled showing empathy to those grieving, including those in Puerto Rico after the devastating hurricane - has emphatically rejected claims that he was disrespectful. But he ignited a storm of his own this week when he boasted about his commitment to calling service members' next of kin and brought Kelly into the controversy by wondering aloud if President Barack Obama had called the former Marine general after the death of Kelly's son.
Kelly confirmed Thursday that Obama had not called, but he made clear "that's not a criticism."
"That's not a negative thing," he said. "I don't believe all presidents call. I believe they all write."
Kelly was not aware that Trump was going to reveal anything he'd said about the time after his son's death, according to a person familiar with the private conversations but not authorized to discuss them publicly.
Kelly did say that when Trump took office, he urged the president not to make those family calls, saying "I said to him, 'Sir there's nothing you can do to lighten the burden on these families.'"
But when Trump indicated he wanted to do so, Kelly revealed to him what General Joseph Dunford, now chairman of the Joint Chiefs of Staff, told him when Robert Kelly was killed. Kelly recalled that Dunford said his son "was doing exactly what he wanted to do when he was killed. He knew what he was getting into. He knew what the possibilities were because we're at war."
And Kelly added that Dunford told him that "when he died, he was surrounded by the best men on this earth, his friends. That's what the president tried to say to four families the other day."
Kelly said the Defense Department is investigating into the details of the Oct. 4 ambush that killed four American soldiers.
Islamic militants on motorcycles brought rocket-propelled grenades and heavy machine guns, killing the four and wounding others after shattering the windows of unarmored U.S. trucks. The attack happened in a remote corner of Niger where Americans and local counterparts had been meeting with community leaders.
Kelly said Thursday that small groups of Americans are being sent overseas, including to Niger, to help train local people to fight the IS group "so that we don't have to send large numbers of troops."
Hs speech was a rebuke to Wilson, who was in the car with the family of Sgt. Johnson when Trump called Tuesday. She said in an interview that Trump had told Johnson's widow that "you know that this could happen when you signed up for it ... but it still hurts."
Kelly aimed his anger at Wilson, whom he also accused of grandstanding at the dedication of a Miami FBI office in 2015. But Johnson's aunt, who raised the soldier as her son, also told The Associated Press on Wednesday that Trump had shown "disrespect" to the family in the call they received as they drove to Miami's airport to receive the body. At the airport, widow Myeshia Johnson leaned in grief across the flag-draped coffin after a military guard received it.
The White House chief of staff said he was so upset by the congresswoman that he went to walk "among the finest men and women on earth," a 90-minute visit to nearby Arlington National Cemetery, where he strode among the graves of fallen service members, including some who died under his command.
Kelly began his remarks by recounting in painstaking detail what happens after a solider is killed in overseas combat. The dead soldier's body is wrapped in a makeshift shroud by his colleagues, Kelly said, and then flown by helicopter to a nearby air base, where it is encased in ice. It is then flown to a second base, often in Europe, and put in more ice before it is transported to Dover Air Force Base in Delaware. The body is then embalmed and dressed in military uniform, complete with medals before heading home.
And, Kelly said, the next of kin are notified by a casualty officer, who "proceeds to break the heart of family members."
Robert Kelly, 29, was killed when he stepped on a land mine in Afghanistan's remote Helmand province. His father, aware that the son accompanied almost patrols through mine-filled battlefields, had just days before warned the family of the potential danger, according to a report in The Washington Post.
Kelly on Thursday said that his family got calls from Robert's friends in Afghanistan attesting to his character. Those calls, he said as he fought back tears, were the most important.
After his dramatic opening statement, Kelly then took questions from reporters, asking first if any of them were Gold Star parents or siblings, meaning relatives of slain service members. When no one raised a hand, Kelly then said he would take questions only from those who knew a Gold Star family.
Kelly, whose frustrations with the distractions created by Trump on other subjects led him to deny last week that he was considering quitting, also bemoaned how the nation no longer held things sacred, from life to religion to women. He also said the sacredness over Gold Star families "left in the convention over the summer," an apparent reference to the vocal campaign battle between the Khan family and Trump.
President Donald Trump's chief of staff says he is "stunned" and "broken hearted" by the criticism of Trump's call to the family of an Army sergeant killed in Niger.
John Kelly tells reporters at the White House that the president had expressed his condolences "in the best way that he could."
The aunt of an Army sergeant killed in Niger said Trump showed "disrespect" to the soldier's loved ones as he telephoned them to extend condolences as they drove to a Miami airport to receive his body.
Florida Democrat Rep. Frederica Wilson said Trump had told the widow that "you know that this could happen when you signed up for it ... but it still hurts."