WASHINGTON (CBSNewYork) — White House Chief of Staff Gen. John Kelly came forward with an unexpected and emotional statement Thursday, addressing the controversy over presidential calls to families of fallen soldiers.

Kelly, a retired four-star Marine general who lost his son Robert in combat, was in the Oval Office when President Donald Trump called the widow of a U.S. soldier killed in Niger.

READ MORE: Intrepid Museum Marks 80 Years Since Pearl Harbor Attack With Wreath-Laying Ceremony

“If you elect to call a family like this, it is about the most difficult thing you could imagine,” Kelly said Thursday. 

Kelly said he explained to Trump beforehand how he had learned about his son’s death and what the officer said to him.

“He said, ‘Kell, he was doing exactly what he wanted to do when he was killed. He knew what he was getting into by joining that one percent, he knew what the possibilities were because we’re at war. And when he died — the four cases we’re talking about in Niger and my son’s case in Afghanistan — when he died, he was surrounded by the best men on this earth, his friends.’ That’s what the president tried to say to the four families the other day.”

The four U.S. soldiers killed in Niger, including Sgt. La David Johnson.

“He said to me, ‘What do I say?’ I said to him, ‘Sir, there is nothing you can do to lighten the burden on these families,'” Kelly said.

READ MORE: Strong Winds Topple Jersey City Building Under Construction; 'Devastated' Neighbors Left Homeless: 'It's A Disaster Right Now'

Trump phoned Johnson’s grieving widow, and the call was overheard by Congresswoman Frederica Wilson, of Florida. She claimed the president said, ‘he knew what he signed up for,’ and called him insensitive.

“I was stunned when I came to work yesterday morning and brokenhearted at what I saw a member of Congress doing – a member of Congress who listened in on a phone call from the president of the United States to a young wife and in his way tried to express that opinion that he’s a brave man, a fallen hero. He knew what he was getting into because he enlisted — there’s no reason to enlist, he enlisted. And he was exactly where he wanted to be with exactly the people he wanted to be with when his life was taken,” Kelly said.

Kelly said he was appalled that Wilson actually overheard what the president said to the widow.

“It stuns me that a member of Congress would have listened in on that conversation, absolutely stuns me. I thought at least that was sacred,” he said. “When I listened to this woman — and what she was saying and what she was doing on TV — the only thing I could do to collect my thoughts was to go walk among the finest men and women on this earth. You can always find them, because they are in Arlington National Cemetery. I went over there for an hour and a half, walked among the stones – some of whom I put there because they were doing what I told them to do when they were killed.”

Wilson responded to Kelly’s comments, saying, “John Kelly is trying to keep his job, he will say anything. There are other people who heard what I heard.”

MORE NEWS: NYC Hospitality Alliance: Mayor De Blasio 'Grinch' For Vaccine Mandate That May Keep Tourists With Young Children Away

Later Thursday, a spokesperson for the congresswoman said in a statement that she will make no further comment. She said the focus should be on helping a grieving widow and family heal, and should not be on her and the president.