The Trump administration has removed Army Lieutenant Colonel Alexander Vindman from his position as the White House's top Ukraine expert after he provided damaging testimony about President Donald Trump during the impeachment process, according to his lawyer.
And in a statement on Friday local time, US ambassador to the European Union Gordon Sondland said Mr Trump was planning to recall him from his post.
"I was advised today that the President intends to recall me effective immediately as United States Ambassador to the European Union," Mr Sondland said, making him the second person to be removed.
Colonel Vindman was escorted out of the White House where he had worked on the National Security Council (NSC), lawyer David Pressman said in a statement, adding that the move was retribution for Colonel Vindman's testimony.
"There is no question in the mind of any American why this man's job is over, why this country now has one less soldier serving it at the White House. LTC Vindman was asked to leave for telling the truth," Mr Pressman said.
Watch Colonel Alexander Vindman's November 2019 statement:
Colonel Vindman testified to the House of Representatives impeachment inquiry in November that Mr Trump made an improper demand of Ukrainian President Volodymyr Zelensky in a July phone call that became the centerpiece of the probe of the Republican president.
Colonel Vindman told a Democratic-run committee: "I couldn't believe what I was hearing" in the phone call.
Mr Trump asked Mr Zelensky to launch investigations into both Democratic rival Joe Biden and a widely debunked conspiracy theory that Ukraine, not Russia, was behind meddling in the 2016 US presidential election.
In that appearance, Colonel Vindman also downplayed concerns that he would suffer payback for speaking out.
"I will be fine for telling the truth," he said.
A spokesman for the NSC declined to comment.
Watch Ambassador Gordon Sondland's statement:
Mr Trump emerged victorious from his trial this week with a vote in the Senate, controlled by fellow Republicans who rejected abuse of power and obstruction of justice charges.
Related: Trump acquitted
Asked earlier on Friday about media reports that he might remove Colonel Vindman, Mr Trump told reporters: "I'm not happy with him. You think I'm supposed to be happy with him?…They're going to be making that decision."
A source familiar with the situation told Reuters that Colonel Vindman would be reassigned to the Defence Department.
Colonel Vindman's two-year stint at the White House was due to end in July.
US Defense Secretary Mark Esper said on Friday that the Pentagon protects all service members from retribution.
Mr Trump, who became only the third US president to be impeached, has said he is still bitter as he turns his attention to seeking a second four-year term in the November 3 presidential election.
Another senior white House aide who testified over impeachment, Jennifer Williams, left this week for a post at the US military's Central Command, according to Bloomberg News.
Mr Trump has cast both Colonel Vindman and Ms Williams as "Never Trumpers" who oppose him.
Mr Trump denied reports that he was weighing a permanent chief of staff to replace acting aide Mick Mulvaney, who was a central figure in the impeachment inquiry.
"That was a false report. I have a great relationship with Mick," Mr Trump said.