The former US ambassador to Ukraine, Marie Yovanovitch, has warned that the US had adopted an "amoral" foreign policy that "substitutes threats, fear and confusion for trust".
In her first public remarks since leaving the US foreign service two weeks ago, Yovanovitch said that the Trump administration's handling of foreign policy risked alienating allies and driving them into the arms of other partners they find more reliable.
The veteran former ambassador was ousted from her post in Kyiv by Donald Trump last May, at the time the president and his associates were putting pressure on the Ukrainian government to launch investigations of Trump's political opponents. Yovanovitch gave evidence about the pressure campaign at congressional impeachment hearings before retiring from the foreign service altogether.
"We need to be principled, consistent and trustworthy," she said while accepting an award for diplomacy at Georgetown University. "To be blunt, an amoral, keep-them-guessing foreign policy that substitutes threats, fear and confusion for trust cannot work over the long haul."
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"At some point, the once unthinkable will become the inevitable - that our allies who have as much right to act in their own self-interest as we do, will seek out more reliable partners partners whose interests might not align well with ours."
Yovanovitch was given a lengthy, thunderous standing ovation by an audience of students and diplomats and beamed as she took the stage. She warned that the state department was "in trouble" adding that its leadership lacked "policy vision" and "moral clarity".
The secretary of state, Mike Pompeo, did not defend her when she was smeared by the president's lawyer, Rudy Giuliani, and did not appear to try to stop her removal from her post. When asked about her last month, Pompeo launched an obscenity-laced tirade against the journalist who raised the question.
Yovanovitch described her months at the centre of the impeachment uproar as a "through-the-looking-glass experience", and said she was forced to "dig deep a little bit" and rely on family, friends, faith and, in the wake of her retirement, fun.
She was given the Trainor Award for Excellence in the Conduct of Diplomacy at Georgetown University. Previous winners have been the then US secretary of state, Madeleine Albright, and then secretary general of the United Nations, Kofi Annan.
And on a brighter note, she said: "With all the focus on Ukraine, it has meant that there is continued bipartisan support for a strong Ukraine policy."
Yovanovitch spoke out in an opinion article for the Washington Post earlier in the month.
She wrote: "These are turbulent times, perhaps the most challenging that I have witnessed. But I still intend to find ways to engage on foreign policy issues and to encourage those who want to take part in the important work of the Foreign Service."
She added: "Like my parents before me, I remain optimistic about our future. The events of the past year, while deeply disturbing, show that even though our institutions and our fellow citizens are being challenged in ways that few of us ever expected, we will endure, we will persist and we will prevail."
Testifying before the House of Representatives in the impeachment inquiry last year, Yovanovitch spoke about the devastating campaign to undermine her work in Ukraine by the president and his confidants, before he ultimately recalled her from the job.
She told impeachment investigators she felt "shocked and devastated" by Trump's personal attacks on her, and that she was "amazed" corrupt elements in Ukraine had found willing American partners to take her down.
Trump tweeted attacks on her even as she testified, accusing Yovanovitch of incompetence, an experience she told the committee that she found intimidating.