Alexander Vindman

NPR's Michel Martin speaks with Mark Esper about his forthcoming book, "A Sacred Oath: Memoirs of a Secretary of Defense During Extraordinary Times."

Russian troops have reportedly entered Kyiv, a significant escalation of the invasion of Ukraine.

Vindman accuses Donald Trump Jr., Rudy Guiliani and others of conspiring to intimidate and then punish him for testifying in the former president's 2019 impeachment case.

When a congressman asked Alexander Vindman why he wasn’t afraid to blow the whistle on former President Trump, he said: "Because this is America. This is the country I’ve served and defended and here, right matters.”

Sen. Tammy Duckworth, D-Ill., had demanded proof that Lt. Col. Alexander Vindman, who retired last week, was included on a list of more than 1,000 officers submitted to the White House for promotion.

Vindman is retiring "after it has been made clear that his future within the institution he has dutifully served will forever be limited," his lawyer said Wednesday.

Lt. Col. Alexander Vindman testified in impeachment hearings. He's been due for promotion to the rank of full colonel, but that has not happened. Sen. Tammy Duckworth wants assurances that it will.

Lt. Col. Alexander Vindman was reportedly escorted out of the White House, while Gordon Sondland was recalled from his post as ambassador to the European Union.

A slate of key witnesses told members of Congress what they'd heard and seen firsthand regarding President Trump and the shadow policy for Ukraine aimed at getting concessions from its leaders.

The House Intelligence Committee is hearing from four more witnesses on Tuesday, including Ukraine specialist Lt. Col. Alexander Vindman and former National Security Council official Tim Morrison.