As former U.S. Ambassador to Ukraine Marie Yovanovitch testified to Congress during the second public hearing in the impeachment inquiry on Friday, President Trump blasted the career diplomat on Twitter. Yovanovitch was recalled from her position earlier this year after the president’s lawyer—and the former New York City mayor—Rudy Giuliani reportedly led a campaign to discredit her. She has said her ouster was organized by “foreign corrupt interests.” “Everywhere Marie Yovanovitch went turned bad,” he wrote. “It is a U.S. President’s absolute right to appoint ambassadors.” Trump added: “They call it ‘serving at the pleasure of the President.’ The U.S. now has a very strong and powerful foreign policy, much different than proceeding administrations. It is called, quite simply, America First! With all of that, however, I have done FAR more for Ukraine than O.”

Minutes later, House Intelligence Committee Chairman Adam Schiff referenced the moment live on Capitol Hill, saying: “Now the president in real time is attacking you. What effect do you think that has on other witnesses?” Yovanovitch called it “very intimidating.” Schiff responded: “Some of us here take witness intimidation very seriously.” Later Friday, the White House slammed that characterization. “The tweet was not witness intimidation, it was simply the President’s opinion, which he is entitled to,” said White House press secretary Stephanie Grisham.