Ahead of Army Lt. Col. Alexander Vindman's Tuesday testimony in the House's impeachment inquiry, cable news hosts and contributors have — without evidence — questioned his loyalty to the U.S. because he was born in Ukraine.

Why it matters: Vindman, a decorated Iraq War veteran and the National Security Council's top Ukraine expert, will say that he conveyed concerns internally to officials after listening to President Trump's July phone call with Ukrainian President Volodymyr Zelensky.

Vindman emigrated to the U.S. from Ukraine when he was a child with his family, per the New York Times. He speaks Ukrainian as well as Russian.

What they're saying:

CNN contributor and former Republican Rep. Sean Duffy: "It seems very clear that he is incredibly concerned about Ukrainian defense. I don't know that he's concerned about American policy, but his main mission was to make sure that the Ukraine got those weapons. We all have an affinity to our homeland where we came from. ... He has an affinity I think for the Ukraine. He speaks Ukrainian. He came from the country, and he wants to make sure they're safe and free."

"It seems very clear that he is incredibly concerned about Ukrainian defense. I don't know that he's concerned about American policy, but his main mission was to make sure that the Ukraine got those weapons. We all have an affinity to our homeland where we came from. ... He has an affinity I think for the Ukraine. He speaks Ukrainian. He came from the country, and he wants to make sure they're safe and free." "Fox & Friends" host Brian Kilmeade: "We also know he was born in the Soviet Union, emigrated with his family — young. He tends to feel simpatico with the Ukraine."

"We also know he was born in the Soviet Union, emigrated with his family — young. He tends to feel simpatico with the Ukraine." Fox News host Laura Ingraham: "Here we have a U.S. national security official who is advising Ukraine while working inside the White House — apparently against the president's interest and usually they spoke in English. Isn't that kind of an interesting angle on this story?"

"Here we have a U.S. national security official who is advising Ukraine while working inside the White House — apparently against the president's interest and usually they spoke in English. Isn't that kind of an interesting angle on this story?" Former deputy attorney general John Yoo replied to Ingraham: "I find that astounding and some people might call that espionage."

Go deeper ... Read: White House Ukraine expert to testify on Trump call concerns