White House officials said that former National Security Council (NSC) member Lt. Col. Alexander Vindman created a hostile work environment, part of a list of allegations sent to the Pentagon after his testimony in President Trump’s impeachment investigations, NBC News reported Wednesday. 

In February, Vindman was escorted out of the White House and told to leave his NSC position after providing damaging testimony last year about Trump’s July 25 phone conversation with Ukraine’s president.

Last week, he announced his retirement from the Army, with his attorney accusing Trump of "a campaign of bullying, intimidation, and retaliation" since Vindman's testimony.

In late 2019, the NSC sent a list of negative claims, including that Vindman was verbally abusive to a colleague, to the Pentagon as he was on schedule to receive a promotion to full colonel, one person who saw the document and two others briefed on it told NBC News. If the allegations were corroborated, the sources said it would have prevented his promotion.

Defense Secretary Mark Esper had reportedly told White House officials that he would not remove Vindman from the list of hundreds of Army officials scheduled to be promoted, warning it would look bad for the president. 

The Pentagon conducted a probe into Vindman’s actions while he was on the NSC but determined it could not substantiate the allegations, people familiar with the document told NBC News, which said the list indicates that the White House attempted to prevent Vindman from being promoted and to retaliate against him for his impeachment testimony.

The NSC, White House and Vindman’s attorney did not immediately respond to a request for comment. The Pentagon declined to comment.

After Vindman was removed from the NSC earlier this year, the president had hinted the military should punish him further, although Esper rejected the possibility. Trump also tweeted about Vindman, calling him “very insubordinate.”

Vindman, a Purple Heart recipient and Iraq combat veteran, was subpoenaed during the House’s impeachment investigation. He told investigators that he heard Trump request that Ukrainian President Volodymyr Zelensky investigate Democratic political opponent Joe Biden during the now-infamous 2019 phone call.