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WATCH: Vindman says he needed to immediately report Trump-Zelensky call

A White House aide says that he told Ukrainian officials to stay out of U.S. politics.

Lt. Col. Alexander Vindman testified publicly on Nov. 19 before a House committee in the impeachment inquiry into President Donald Trump. Watch in the player above.

Vindman was on a July 25 call between Trump and Ukraine’s new president where Trump pressed for investigations into the 2016 presidential election and the son of his Democratic rival.

Vindman said he knew “without hesitation” that he had to report the call to the White House counsel.

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He told the committee that another official, U.S. Ambassador Gordon Sondland, later said the Ukrainians needed to provide “a deliverable” which was “specific investigations.”

Vindman later told Ukrainian officials they should steer clear of the requests.

Trump has denied any wrongdoing.