Confirming reports that President Donald Trump fumes about the special counsel investigation into Russia’s election interference to any White House staffer or journalist on hand, his deputy assistant Sebastian Gorka told the BBC on Monday that they’ve chatted about the probe behind closed doors.

These private discussions, which Gorka also claimed to have had with Trump’s son-in-law and senior adviser Jared Kushner, make him a potential fact witness for special counsel Robert Mueller. Mueller’s wide-ranging investigation is reportedly looking into whether Trump has attempted to obstruct justice ; Trump and his associates’ business and real estate dealings; and whether members of the Trump campaign colluded with Russian operatives to secure his electoral victory.

In the testy interview, BBC’s Stephen Sackur asked how Gorka could have the “arrogance” to insist that the Russia investigation is a so-called “nothing burger,” since he has “no idea what [special counsel] Robert Mueller is collecting.”

“You can insult me on television,” Gorka replied, “but I actually work for the President of the United States. And when he tells me there’s nothing there, privately, and when Jared [Kushner] tells me there’s nothing there, you know what? I’m going to actually trust my employer.”

Sackur reiterated that Gorka could have no idea what Mueller and his team of high-powered attorneys were digging up.

“I know what the President of the United States told me and that’s enough for me,” Gorka insisted. “Because I trust that man. I have no connection to Robert Mueller.”

Those comments add Gorka to a long list of known and potential fact witnesses that Mueller’s team may want to question regarding the President’s deliberations about the Russia probe.