In its historic vote, the Senate decided not to remove America's 45th president from office on charges arising from his dealings with Ukraine.
Hours later, US President Donald Trump dismissed two senior officials who testified against him at his impeachment trial.
The US envoy to the EU, Gordon Sondland, said he "was advised today that the president intends to recall me effective immediately."
Just hours earlier, Lt Col Alexander Vindman, a top expert on Ukraine, was escorted from the White House.
Mr. Trump is said to desire a staff shake-up after senators cleared him in the impeachment case on Wednesday.
Lt Col Vindman's twin brother, Yevgeny Vindman, a senior lawyer for the National Security Council, was also sent back to the Department of the Army on Friday.