Gold Star father Khizr Khan took issue Sunday with White House Chief of Staff John Kelly, saying Kelly and President Trump disrespected military servicemen and women with their comments over the past week.

Appearing on CBS’ “Face the Nation” to publicize his memoir entitled, “An American Family: A Memoir of Hope and Sacrifice,” Khan said Kelly “indulged in defending behavior of the president and made the situation even worse.”

He criticized Kelly for standing by President Donald Trump, who engaged in a very public feud on TV and Twitter last week over Gold Star families.

Khan, the father of U.S. soldier Humayun Khan, who was killed in Iraq, added that “restraint and dignity” should be “the call of the moment” when dealing with Gold Star families, instead of turning them into a “political football.”

His comments came more than a year after the Democrats gave him a major platform: the party's 2016 convention. Khan said on stage that Trump had “sacrificed nothing and no one” for America — unlike Humayun, who posthumously received a Bronze Star and a Purple Heart after a suicide bomber killed him in 2004.

Trump later challenged Khizr Khan’s claims. “I’ve made a lot of sacrifices,” Trump said. “I work very, very hard. I’ve created thousands and thousands of jobs, tens of thousands of jobs, built great structures.”

Trump has been engaged in an ongoing feud with Democratic Rep. Frederica Wilson, D-Fla., who said she listened in to a condolence call he made last week to an Army widow. Wilson said Trump told the widow that her deceased husband, Army Sgt. La David Johnson, “knew what he signed up for.” Trump denied it.

Kelly on Thursday publicly criticized Wilson’s involvement in the call and also suggested she was trying to politicize the matter.

Wilson also suggested that Kelly, whose son was killed in Afghanistan, was forced to make public statements on the call to save his job, amid speculation that Trump is unhappy with his performance.

Khan, a Charlottesville resident, also expressed shock on “Face the Nation” about seeing Kelly “standing next to the President when the President could not have the proper words to condemn the attack on the blessed city of Charlottesville, Virginia by Neo-Nazis.”

Trump was criticized for saying “both sides” were to blame after white nationalists and alt-right groups gathered in the southern town to protest the removal of a Confederate statue on August 12, sparking violence. Police said a Nazi sympathizer plowed his car through a group of counter-protesters, killing 32-year-old Heather Heyer, a paralegal.

The Associated Press contributed to this report.