READ IT: Vindman calls out Trump allies for attacking impeachment witnesses in opening statement

Lt. Col. Alexander Vindman called out attacks on his character as he accused President Donald Trump of engaging of inappropriate discussions with Ukraine's president.

The National Security Council staffer testified that he believed Trump's request for an investigation of Joe Biden was inappropriate, and he reported the call and his concerns through official channels to a superior out of a sense of duty, according to his opening statement.

“I was concerned by the call, what I heard was improper, and I reported my concerns to [White House lawyer] Mr. Eisenberg,” Vindman said in his opening statement. “It is improper for the President of the United States to demand a foreign government investigate a U.S. citizen and political opponent."

"It was also clear that if Ukraine pursued an investigation into the 2016 election, the Bidens, and Burisma, it would be interpreted as a partisan play," he added. "This would undoubtedly result in Ukraine losing bipartisan support, undermine U.S. national security, and advance Russia’s strategic objectives in the region.”

He then shamed Trump's allies of smearing him and his colleagues because they have complied with congressional subpoenas.

“I want to take a moment to recognize the courage of my colleagues who have appeared and are scheduled to appear before this Committee,” Vindman said. “I want to state that the vile character attacks on these distinguished and honorable public servants is reprehensible. It is natural to disagree and engage in spirited debate, this has been our custom since the time of our Founding Fathers, but we are better than callow and cowardly attacks.”