Sen. Thom Tillis, R-N.C., commented Friday on the firing of Lt. Col. Alexander Vindman, who made waves as a witness during House Democrats' impeachment inquiry.

"Well, now you have to keep in mind the testimony. Col. Vindman said that he thought that the conversation with the president of Ukraine brought up serious policy concerns," Tillis said on "Your World with Neil Cavuto." "You're talking about the president of the United States, who gets to set foreign policy. But it's also important to remember that Col. Vindman's boss and his boss's boss was on the line and they testified that they didn't see any issue with the conversation."

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Fox News confirmed Friday that Vindman was fired by the National Security Council, where he was on detail from the Department of Defense, and escorted off of the White House grounds.Vindman is expected to return to the Pentagon.

Vindman's dismissal comes just two days after the Senate acquitted President Trump on both articles of impeachment brought by the House over his dealings with Ukraine. Vindman was an important witness for Democrats, as he raised concerns over Trump’s July 25 phone call with Ukrainian President Volodymyr Zelensky, in which Trump pressed Kiev to launch an investigation concerning presidential candidate Joe Biden's family.

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Tillis reiterated to Cavuto that the president sets foreign policy and expects his staff to carry it out.

"So this is a lower-level person who suddenly decides that he's going to express a concern about policies when the president of the United States determines policy," he said. "He expects his staff to execute it."

Fox News' John Roberts and Brooke Singman contributed to this report.