A former chairman of the Joint Chiefs of Staff on Sunday slammed John Kelly for backing Donald Trump “no matter what.”

Retired Adm. Michael Mullen said on ABC’s “This Week” that he was particularly disappointed that Kelly, the White House chief of staff, backed Trump after the president’s ugly confrontation over his controversial condolence call to the widow of Army Sgt. La David Johnson, one of four soldiers killed in Niger.

Kelly defended Trump at a press briefing in October after Myeshia Johnson and Rep. Frederica Wilson (D-Fla.) complained that the president apparently couldn’t remember the fallen soldier’s name on the phone, and told his widow that her dead husband knew what he “signed up for.”

Besides taking a position against a “Gold Star family,” Mullen said, “John [also] ends up politicizing the death of his own son.” After the Johnson controversy, Trump complained that Kelly didn’t get a phone call from former President Barack Obama after Kelly’s son, a Marine, was killed in Afghanistan.

Kelly’s actions indicated that he “clearly is very supportive of the president no matter what,” Mullen said. “That was really a sad moment for me.”

Mullen said he has concerns about retired or active generals serving in the highly charged political atmosphere of Trump’s White House. Men like Kelly, National Security Adviser H.R. McMaster (a lieutenant general still on active duty) and Defense Secretary James Mattis bring stability and tend to reassure people during a “chaotic year,” said Mullen. But politics is a “foreign” and “difficult” atmosphere for them, he added, and their presence threatens to politicize the military.

“That doesn’t mean generals and admirals can’t serve” in the White House, Mullen said. “They certainly have in the past. But it’s particularly difficult right now because of the politics of the town. And there’s nothing that seemingly is not able to be politicized in the current environment.”

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Despite his criticism, Mullen called Kelly, McMaster and Mattis “great Americans and ... great citizens, and I know that each of them are serving to try to do their best for the country.”

Mullen also said he believes the use of nuclear weapons seems “more probable than it used to be — and it scares me to death.”

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