Ukraine Envoy Says She Was Told Trump Wanted Her Out Over Lack of Trust

More broadly, she portrayed the State Department as a whole as “attacked and hollowed out from within.” Unless it backs up its diplomats, especially in the face of false attacks by foreign interests, she said, more of them will leave and the wrong message will be transmitted around the world.

“Bad actors” in Ukraine and elsewhere will “see how easy it is to use fiction and innuendo to manipulate our system,” she warned. “The only interests that will be served are those of our strategic adversaries, like Russia.”

She had been removed from her post in Ukraine before the events most at the heart of the impeachment inquiry: whether Mr. Trump withheld White House meetings or military aid to Ukraine this spring and summer to pressure its new president, Volodymyr Zelensky, to Mr. Biden and his younger son, Hunter Biden.

That Ms. Yovanovitch, who remains a State Department employee, showed up at all to testify was remarkable. In a letter this week, the White House counsel, Pat A. Cipollone, lashed out at the impeachment inquiry, saying government officials would not testify and that no documents would be provided. The White House did not respond to requests for comment on Friday.

Ms. Yovanovitch’s defiance of the administration’s directive against appearing before the impeachment proceeding raises the possibility that other government officials will follow suit. She called upon the State Department leaders and Congress to defend the institution, saying “I fear that not doing so will harm our nation’s interest, perhaps irreparably.”

The turnabout appeared to validate the tactics adopted by Democrats, who have issued rapid-fire subpoenas since they opened the inquiry two weeks ago and warned that any attempts by the administration to block their fact-finding will promptly become fodder for an article of impeachment charging Mr. Trump with obstructing Congress. When the State Department tried late Thursday to direct Ms. Yovanovitch not to appear, the Democrats promptly issued a subpoena and told her she had no choice but to appear.

At least one other State Department official is also expected to testify, despite the White House policy. Gordon D. Sondland, the ambassador to the European Union who was initially expected to testify this week but failed to show up, has now been rescheduled for next week. Mr. Sondland is close to Mr. Trump and could support the White House’s narrative that the administration’s policy in Ukraine has been driven by a focus on rooting out corruption.