WASHINGTON, D.C. — Even as former U.S. Ambassador to Ukraine Marie Yovanovitch warned Friday about the national security risks of publicly undermining American diplomats in the foreign service, President Donald Trump took to Twitter in real time to try to discredit her and defend his decision to recall her from her post.

Yovanovitch, the latest career diplomat to testify in the House impeachment inquiry, said during the second day of public hearings that openly criticizing U.S. officials working in foreign countries only serves to undercut U.S. interests and may encourage foreign leaders to attempt to sideline American diplomats pushing for difficult but needed reforms.

“Shady interests the world over have learned how little it takes to remove an American ambassador who does not give them what they want,” she said, referring to her ouster in May following what she calls a smear campaign by some in the Trump administration. “After these events, what foreign official, corrupt or not, could be blamed for wondering whether the ambassador represents the president’s views?”

As she testified, Trump went on Twitter to criticize her and defend his right to hire and fire ambassadors at will. He claimed without evidence “that everywhere Marie Yovanovitch went turned bad.” During the first hearing, on Wednesday, Trump was silent on Twitter during the proceeding and said he was not watching it.

Rep. Adam B. Schiff, chairman of the House Intelligence Committee, paused questioning Friday to read the tweet and defend Yovanovitch’s impressive 33-year record with the State Department. He accused the president of trying to intimidate her and others who are cooperating with the inquiry.

“We saw today witness intimidation in real time,” said Schiff, D-Calif.

Yovanovitch said that she believed her anti-corruption efforts made her a target of dishonest Ukrainians who were opposed to U.S. efforts to clean up the government there. What shocked her, she said, was that they appeared to have found allies in the Trump administration.

“What continues to amaze me is that they found Americans willing to partner with them, and working together, they apparently succeeded in orchestrating the removal of a U.S. ambassador,” she said. “(I) do not understand Mr. Giuliani’s motives for attacking me, nor can I offer an opinion on whether he believed the allegations he spread about me.”

The career foreign service officer has been framed by Democrats as the first victim of Trump’s scheme in Ukraine, and her testimony gets to their narrative that Trump abused his power in a way that damaged U.S. interests. She was recalled by Trump in May after a weekslong campaign by former Ukrainian officials that was amplified by conservative media outlets, the president’s personal attorney Rudolph W. Giuliani and the president’s son Donald Trump Jr. The abrupt removal came just two months after Yovanovitch was asked by the State Department to stay on through 2020.

Trump’s attack on a well-regarded career foreign service employee while she was testifying about efforts to stop corruption overseas was immediately seen by some as a misstep. Former independent counsel Kenneth Starr called it “quite injurious” on Fox News. “I must say the president was not advised by counsel in deciding to do this tweet. Extraordinarily poor judgment,” said Starr, who led the investigation into former President Bill Clinton.

Republican Intelligence Committee member Rep. Elise Stefanik of New York told reporters during a break that she disagreed with the president’s tweet.

But Trump ally Rep. Lee Zeldin, R-N.Y., defended the president’s tweet. “The president is going to defend himself,” Zeldin said. “It’s about the president wanting to ensure that the entire story is getting out there for the American public.”

Democrats on the House Intelligence Committee are weighing whether to file articles of impeachment against the president after learning that for months he and allies worked to leverage $400 million in aid and a White House meeting to coerce new Ukrainian President Volodymyr Zelenskiy into publicly committing to begin investigations into the 2016 election and a natural gas company that employed the son of a potential 2020 Trump rival, former Vice President Joe Biden. The inquiry continues next week with three days of public hearings.

The inquiry began with a whistleblower complaint that raised concerns about the content of a July 25 phone call between Trump and Zelenskiy, but Democrats have seized on a broader narrative that Trump and Giuliani worked on foreign policy outside the normal, established boundaries in order to benefit the president politically.

“She’s really witness to, and kind of the victim of, the first chapter” of the plan, said an official working on the impeachment inquiry who was not authorized to speak publicly.

Yovanovitch and other State Department witnesses told representatives in closed-door depositions that the envoy, who has served under both parties and was known for her anti-corruption efforts in post-Soviet countries, was seen as a hindrance to that plan and was driven out through a concentrated effort to convince Trump and conservatives that she favored Democrat Hillary Clinton in the 2016 presidential election.

Transcripts of depositions show several others have testified that the accusations against Yovanovitch have no basis in fact, and that a former Ukrainian prosecutor bragged about lying about the diplomat to an American journalist, who published several articles about Yovanovitch in March 2019 that were quickly picked up by conservative media personalities including Sean Hannity and Laura Ingraham. The State Department largely declined to defend Yovanovitch despite pleas from embassy employees, other witnesses have said.

“This is about far more than me or a couple of individuals,” Yovanovitch said. “As foreign service professionals are being denigrated and undermined, the institution is also being degraded. This will soon cause real harm, if it hasn’t already.”

Yovanovitch told lawmakers that she was told Secretary of State Michael R. Pompeo and the State Department would not defend her because “it could be undermined, that the president might issue a tweet contradicting it.”

Rep. Eric Swalwell, a member of the Intelligence Committee, said before the testimony that while the president has the right to hire and fire federal employees, Yovanovitch “was fired to clear the decks for the president’s corrupt scheme to play out.”

“Yes, it’s humiliating that he smeared her, that others were smearing her and that she lost her job in Ukraine because of it. But this is bigger than her,” said Swalwell, D-Calif. “Are presidents allowed to use ambassadors or move ambassadors so that they can corruptly benefit from it?”

Just as the hearing began, the White House released a summary memo of an April call in which Trump congratulated Zelenskiy for winning the Ukrainian election. It was unclear whether the account is a complete transcript. It does not include talk about corruption in Ukraine, something specifically highlighted in the White House readout of the call released in April.

Ahead of Yovanovitch’s testimony, Trump ally Rep. Mark Meadows, R-N.C., dismissed it as a sideshow, saying she was recalled to Washington in May, months ahead of the July 25 phone call between Trump and Zelenskiy.

“She was not there during the relevant time that this whole impeachment inquiry is to address. She was gone. And so, this is a sidebar meant to have a different narrative that has nothing to do with the potential impeachable offenses,” Meadows said.

He said Democrats are putting Giuliani front and center on purpose.

“They believe by impeaching Giuliani they can impeach the president,” Meadows said. “That’s a harder sell on Main Street.”