WASHINGTON — An Army officer who was a prominent witness during the impeachment inquiry into President Trump last year said on Wednesday that he had decided to retire after what his lawyer called a campaign of White House intimidation and retaliation.
The incident is the latest in what Pentagon and congressional officials say could be another flash point between the president and the military.
The witness, Lt. Col. Alexander S. Vindman, a decorated Iraq war veteran who served on the staff of the White House National Security Council, is among scores of officers who have been picked to be promoted to full colonel this year. Typically, such promotions are backed by Army and Pentagon officials before moving to the White House for final approval, and then to the Senate for a confirmation vote.
But the White House had made clear to officials in the Pentagon’s office of personnel and readiness, which handles such matters, that Mr. Trump did not want to see Colonel Vindman promoted, officials said.
Mr. Trump’s allies at the White House asked Pentagon officials to find instances of misconduct by Colonel Vindman that would justify blocking his promotion, administration officials said on Wednesday.
On multiple occasions, including this week, the White House pressed the Pentagon to seek witnesses who would come forward and say that Colonel Vindman acted improperly, the officials said.
But Defense Secretary Mark T. Esper and Army Secretary Ryan McCarthy have been unable to produce such evidence, largely because it does not exist, according to one administration official who spoke on the condition of anonymity.
With that hurdle cleared, Mr. Esper on Monday approved the promotion list, including Colonel Vindman, and it was expected to be delivered to the White House by Friday, a second administration official said.
Senior Army leaders were caught off guard by Colonel Vindman’s decision on Wednesday. Mr. McCarthy was expected to have a general officer contact Colonel Vindman to discuss his options, an administration official said.
But people familiar with Colonel Vindman’s decision said he felt increasingly pessimistic that he had a meaningful future in the Army. He announced his decision in a short Twitter message on Wednesday morning.
“Today I officially requested retirement from the US Army, an organization I love,” he said. “My family and I look forward to the next chapter of our lives.”
Colonel Vindman’s lawyer, David Pressman, said in a statement that the officer was the victim of campaign of “bullying” and “intimidation” by the White House.
“Through a campaign of bullying, intimidation and retaliation, the president of the United States attempted to force LTC Vindman to choose: Between adhering to the law or pleasing a president,” Mr. Pressman said. “Between honoring his oath or protecting his career. Between protecting his promotion or the promotion of his fellow soldiers.”
Mr. Pressman added, “Vindman did what the law compelled him to do; and for that he was bullied by the president and his proxies.”
The White House declined to comment.
In his role as a Ukraine expert on the National Security Council staff, Colonel Vindman was on Mr. Trump’s phone call on July 25 with Ukraine’s president that later was a central element of the impeachment inquiry. Colonel Vindman testified in the House impeachment hearings that it was “improper for the president” to coerce a foreign country to investigate a political opponent.
Hours before Colonel Vindman was marched out of the White House in February by security guards, Mr. Trump foreshadowed his fate when asked if he would be pushed out. “Well, I’m not happy with him,” the president told reporters. “You think I’m supposed to be happy with him? I’m not.”
A person familiar with Colonel Vindman’s decision said he decided to retire after more than 21 years in the Army when it became apparent he would not be able to serve in a useful capacity in his area of specialty, Eurasia affairs. He had been scheduled to start a term at the Army War College later this summer.
Colonel Vindman’s retirement, which still must be approved by the Army, comes despite promises from Mr. Esper and other senior military leaders to protect from retribution members of the armed services who return to military duties after serving tours at the White House.
Senator Tammy Duckworth, Democrat of Illinois, said last week that she would block Senate confirmation of 1,123 military personnel promotions until she received assurances that Colonel Vindman’s promotion would not be blocked.
“Lt. Col. Vindman’s decision to retire puts the spotlight on Secretary of Defense Mark Esper’s failure to protect a decorated combat veteran against a vindictive commander in chief,” Ms. Duckworth said in a statement on Wednesday.