A lawyer for Lt. Col. Alexander Vindman—the National Security Council official who raised concerns about President Trump’s July 25 call with the Ukrainian president—wrote a letter to Fox News asking the network to retract an October TV segment that suggested his client was a spy, The New York Times reports. “LTC Vindman and his family have been forced to examine options, including potentially moving onto a military base, in order to ensure their physical security in the face of threats rooted in the falsehood that Fox News originated,” attorney David Pressman wrote in the letter, adding that the TV segment prompted more false claims against his client.

The letter reportedly referred to an Oct. 28 segment of The Ingraham Angle that suggested Vindman was guilty of espionage. “Here we have a U.S. national security official who is advising Ukraine, while working inside the White House, apparently against the president’s interest, and usually, they spoke in English,” host Laura Ingraham said during the show. “Isn’t that kind of an interesting angle on this story?” John Yoo, a top lawyer in the George W. Bush administration and a guest on the show that night, said he found what Ingraham said “astounding.” “Some people might call that espionage,” Yoo said. Yoo later claimed he was accusing Ukraine of running an espionage operation, rather than calling Vindman “a spy.” A Fox News spokesperson told The Daily Beast that Yoo was “responsible for his own sentiments and he has subsequently done interviews to clarify what he meant.”