Trump stirred outrage Monday when he falsely claimed that President Obama did not personally call the families of U.S. soldiers killed in combat. The comment prompted Obama’s former deputy chief of staff to call the claim an “eff-ing lie” while blasting Trump as a “deranged animal.” On Tuesday, the president doubled down on the claim in an interview with Fox News Radio.

President Donald Trump: “To the best of my knowledge, I think I’ve called every family of somebody that’s died. And it’s the hardest call to make. And I said it very loud and clear yesterday. The hardest thing for me to do is do that. Now, as far as other representatives, I don’t know. I mean, you could ask General Kelly: Did he get a call from Obama? You could ask other people. I don’t know what Obama’s policy was. I write letters and I also call.”

Trump was referring to his chief of staff, retired Marine Corps General John Kelly, whose son, First Lieutenant Robert Kelly, died in Afghanistan in 2010 when he stepped on a landmine. Kelly has previously refused to discuss his son’s death publicly. The Washington Post reports John Kelly attended a 2011 breakfast held by President Obama for Gold Star families.