National Security Council
In July 2018, Vindman accepted an appointment with the National Security Council. In his role on the NSC, Vindman became part of the U.S. delegation at the inauguration of Ukraine's newly elected president, Volodymyr Zelenskyy. The five-member delegation, led by Rick Perry, United States Secretary of Energy, also included Kurt Volker, then U.S. Special Representative for Ukraine Negotiations; Gordon Sondland, United States Ambassador to the European Union, and Joseph Pennington, then acting chargé d'affaires.
Vindman was subpoenaed to testify before Congressional investigators on October 29, 2019, as part of the U.S. House of Representatives' impeachment inquiry against Donald Trump. He was the first White House official to testify who was on a July 25, 2019, telephone call between President Trump and Ukrainian President Volodymyr Zelenskyy, in which Trump asked Zelenskyy to investigate former Vice President Joe Biden's son Hunter Biden, while his father was campaigning for president. Vindman's testimony corroborated previous testimony from Fiona Hill, his former supervisor, and William B. Taylor Jr., acting Ambassador to Ukraine.
On October 28, 2019, Vindman's opening statement to the House Intelligence Committee, House Foreign Affairs Committee, and House Oversight Committee was released, ahead of his testimony on the following day. Vindman testified that: "In Spring of 2019, I became aware of outside influencers promoting a false and alternative narrative of Ukraine inconsistent with the consensus views of the interagency", which was "harmful to U.S. national security" and also "undermined U.S. Government efforts to expand cooperation with Ukraine". He also stated regarding U.S.–Ukraine relations: "Our partnership is rooted in the idea that free citizens should be able to exercise their democratic rights, choose their own destiny, and live in peace," and that "it has been a great honor to serve the American people and a privilege to work in the White House and on the National Security Council".
Vindman said that he was concerned by two events, both of which he objected to with senior officials in real time, and which he reported to the National Security Council's lead attorney. The first event occurred at a July 10 meeting between Ukraine's then Secretary of National Security and Defense Council Oleksandr Danylyuk, and then US National Security Advisor John Bolton, at which Ambassadors Volker and Sondland, and Energy Secretary Rick Perry were in attendance, and at which Sondland asked Ukraine to launch investigations into the Bidens in order to get a meeting with President Trump. Vindman states that Bolton cut the meeting short, and that both Vindman and Hill told Ambassador Sondland that his comments were inappropriate and reported their concerns to the lead counsel of the NSC.
The second event was during a July 25 telephone call between Presidents Trump and Zelenskyy. Vindman states, "I was concerned by the call. I did not think it was proper to demand that a foreign government investigate a U.S. citizen, and I was worried about the implications for the U.S. Government's support of Ukraine. I realized that if Ukraine pursued an investigation into the Bidens and Burisma, it would likely be interpreted as a partisan play which would undoubtedly result in Ukraine losing the bipartisan support it has thus far maintained. This would all undermine U.S. national security." Vindman also stated that he reported his concern to the NSC's lead counsel, John Eisenberg.
Vindman later testified in person before the U.S. House of Representatives on November 19, 2019. In his testimony, Vindman stated that in the course of his official duties and standard NSC coordination obligations, he provided a summary of the call via classified means to two core members of his policy committee, one of whom was an intelligence official, concluding that the President's "demand" for an investigation was "improper". Because of his testimony, Vindman was denounced by Trump and repeatedly attacked by Republican lawmakers and television commentators. As a result, he reached out to the Army regarding his and his family's safety.
In his opening statement, Vindman assured his father that he had made the right decision in emigrating from the Soviet Union to the United States. Vindman said, "In Russia, my act of... offering public testimony involving the President would surely cost me my life. I am grateful for my father's brave act of hope 40 years ago and for the privilege of being an American citizen and public servant, where I can live free of fear for mine [sic] and my family's safety. Dad, my sitting here today, in the U.S. Capitol talking to our elected officials is proof that you made the right decision forty years ago to leave the Soviet Union and come here to United States of America in search of a better life for our family. Do not worry, I will be fine for telling the truth."
On February 7, 2020, Vindman told NSC colleagues he expected to leave the White House's National Security Council to return to the Department of Defense months ahead of his scheduled return to the Army in the summer of 2020. Trump earlier had implied he might remove Vindman from his post. According to his attorney, later that day Vindman was fired and escorted out of the White House. At the same time, his twin brother, Lieutenant Colonel Yevgeny Vindman, also was escorted off the White House grounds. Both had been slated for reassignment within the Army. Subsequent news reports indicated that Vindman had been chosen to attend the in-residence course at the United States Army War College during its 2020–2021 session and for promotion to Colonel.
On February 10, 2020, Senate Minority Leader Chuck Schumer (D-NY) sent a letter in an apparent response to the removal of the two brothers that requested federal Inspectors General investigate possible retaliation against "anyone who has made, or in the future makes, protected disclosures of presidential misconduct". On February 13, Trump's former chief of staff, retired Marine General John Kelly, defended Vindman's actions and testimony. "He did exactly what we teach them to do from cradle to grave. He went and told his boss what he just heard", Kelly said.
During a panel discussion held on February 11, 2020, at the Atlantic Council, the president's National Security Advisor, Robert C. O'Brien said that it was his decision to transfer both Vindman brothers back to the Army for re-assignment and he denied that the move was ordered by Trump in retaliation for Vindman's testimony. "I can absolutely tell you that they were not retaliated against", O'Brien told the panel. O'Brien also disputed the move as being characterized as "fired" since both brothers remained on active duty. O'Brien said that their transfer was part of a larger NSA staff reduction. He was contradicted by Trump, who tweeted that he had ousted Vindman for insubordination and for doing "a lot of bad things".
On July 2, 2020, Senator Tammy Duckworth announced that she intended to block Senate confirmation of more than one thousand military promotions unless defense secretary Mark Esper provided written confirmation that the Trump administration would not continue to block Vindman's promotion to colonel. Less than a week later, in order to avoid a mandatory three-year additional duty service obligation (ADSO), with the continued delay in promotion of hundreds of his peers, along with the knowledge that the White House Chief of Staff Mark Meadows had compelled a highly irregular Army investigation into Vindman and berated the Secretaries of the Defense and the Army for considering his promotion, Vindman announced through his attorney that he would be retiring from the U.S. military. His attorney, David Pressman said that "a campaign of bullying, intimidation, and retaliation" by the Trump administration was the reason for his client's retirement.