WASHINGTON (Reuters) - Inside the hearing room, U.S. Republican lawmakers repeatedly thanked Army Lieutenant Colonel Alexander Vindman for his military service on Tuesday before challenging his testimony about President Donald Trump’s dealings with Ukraine.

National Security Council aide Lt. Col. Alexander Vindman, takes a break as he testifies beforebefore the House Intelligence Committee on Capitol Hill as part of the impeachment inquiry into U.S. President Donald Trump, in Washington, U.S., November 19, 2019. Jacquelyn Martin/Pool via REUTERS

But outside the ornate chamber in the House of Representatives, it was a different story, with the White House and its backers unleashing on social media a full-throated attack on the uniformed officer’s credibility and loyalty.

Vindman, a decorated Iraq war veteran serving as the White House National Security Council’s top Ukraine expert, testified before lawmakers in an ongoing impeachment inquiry led by House Democrats.

His family left the Soviet Union for the United States when he was three years old. Vindman testified that Trump’s request that Ukraine investigate a domestic political rival was an improper demand.

“Lt. Col. Vindman was offered the position of Defense Minister for the Ukrainian Government THREE times!” Trump aide Dan Scavino wrote on Twitter.

While factually correct, Vindman told the lawmakers that as a loyal American, he would not consider such an offer. He called it “comical.”

Trump himself was dismissive when asked about Vindman on Tuesday. “I never saw the man, I understand now he wears his uniform when he goes in,” Trump said.

Slideshow ( 2 images )

Vindman usually wears a suit, not his uniform, while working at the White House, one Republican lawmaker, Representative Chris Stewart, observed. It is standard practice for military officers to wear their uniforms when testifying on Capitol Hill.

Last month Trump described Vindman as a “Never Trumper,” using a term for Republicans who oppose Trump.

Republican lawmakers at the televised hearing appeared keen not to cross a line that would upset constituents with a background in military service.

“Lieutenant Colonel Vindman, I think all of us would agree that your father made the right move to come here, and we’re glad that he did,” Representative Will Hurd told Vindman in one of the warmer accolades from Intelligence Committee Republicans.

Tensions emerged, however. At one point Vindman instructed the senior committee Republican, Representative Devin Nunes, not to call him Mr. Vindman. “It’s Lieutenant Colonel Vindman please,” Vindman said.

Stewart asked: “Do you always insist on civilians calling you by your rank?”

“I just thought it was appropriate,” Vindman replied.

Representative Mark Meadows, a Republican ally of Trump’s, said critics can question Vindman’s judgment, but should respect his service to the country.

“Every person who serves needs to be applauded for their service. But it doesn’t mean their judgment is 100% above reproach,” Meadows said outside the hearing.

Others saw the attacks on Vindman differently.

“We have never questioned the patriotism of Republicans, but today’s vile attacks on Lt. Col. Vindman, for simply doing his duty as he saw fit, leaves us truly shaken,” Will Goodwin, the director of government relations for VoteVets.org, wrote on Twitter.