According to transcripts released on November 8 in the House Democrats' impeachment inquiry, Vindman and Fiona Hill, a former White House Russia adviser, both gave firsthand descriptions of scenes central to the congressional probe.
She and Vindman both said acting White House Chief of Staff Mick Mulvaney and Trump-appointed Ambassador to the European Union Gordon Sondland were behind the pressure on Ukraine to investigate Democratic presidential contender Joe Biden.
The testimony details how top USA officials were alarmed that Trump had outsourced Ukraine policy to his attorney, Rudy Giuliani, who had pushed top Ukraine officials to publicly announce an investigation into the Bidens and to pursue a conspiracy theory that Ukraine interfered in the 2016 elections to help Democrats.
Also on Friday, attorney Charles Cooper who represents Mr Trump's former national security adviser, Mr John Bolton, sent a letter to House lawmakers that suggested that Mr Bolton knows about "many relevant meetings and conversations" concerning Mr Trump's actions towards Ukraine.
Just before boarding Air Force One on the tarmac at Joint Base Andrews, the president said this communication took place in April before the July conversation that was released earlier last month, CNN reported.
Speaking to the Guardian on Friday, Frank O Bowman III, author of High Crimes and Misdemeanors: A History of Impeachment for the Age of Trump and a professor at the University of Missouri school of law, said the White House "gag rule" on senior advisers testifying was "completely abnormal". According to Vindman's recollections and his contemporaneous notes of the call, Mr. Trump's comments that "there are recordings" were replaced in the call summary by ellipses.
But minutes later in another White House room, Sondland continued to press the investigations requirement with the Ukrainians, further alarming the two officials.
As for the future, Ivanka Trump said she had yet to decide on what role she will play in her father's re-election campaign.
She said the individual's identity is not "particularly relevant" to her, "aside from what the motivation behind all of this was".
The call and concerns over it became known when an intelligence services whistleblower filed an anonymous report.
"I don't care if public - they should be public".
"You are going to read the 2d call, and you might perhaps perhaps well moreover expose me if there is the leisure defective with it", he talked about.
"Now, they want to have a transcript of the other call, the second call, and I'm willing to provide that", Trump said.
There is no evidence of wrongdoing by either Joe or Hunter Biden in Ukraine.
This States that the Democrats have already held a number of important hearings and signaled the end of this phase of closed testimony, authorities released thousands of pages of declassified transcripts.
At one point in Vindman's testimony, his lawyer objected to questions from Republicans he believed were meant to draw out the identity of the whistleblower who filed the initial complaint. And that means that for most people outside the world of politics, the real impeachment inquiry will begin next week.
Pressed repeatedly, Volkov said, "He tells you he's not the whistleblower, OK?"