By the time Lieutenant Colonel Alexander Vindman left the House Ways and Means Committee hearing room on Tuesday, it was clear that Republicans were not pleased with what the 44-year-old combat veteran had to say when he testified during the first of two sessions on Tuesday, the third day of impeachment hearings before the House Permanent Select Committee on Intelligence.

They didn't like that Lt Col Vindman, a Ukraine expert detailed to the National Security Council, had worn his Army dress uniform when he raised his right hand to swear to tell the truth, the whole truth and nothing but the truth, and they certainly weren't pleased with how he then proceeded to speak calmly and authoritatively about the concerns he had with what President Donald Trump said during his so-called "perfect" phone call with Volodymyr Zelensky, the president of Ukraine.

"I was concerned by the call. What I heard was inappropriate, and I reported my concerns to [National Security Council legal advisor John] Eisenberg. It is improper for the president of the United States to demand a foreign government to investigate a US citizen and a political opponent," Lt Col Vindman told committee members in a prepared statement.

They didn't like how Vindman, who emigrated to the United States from the former Soviet Union as a child, pointed out that what he came to Capitol Hill to do -- speak out about how it was "improper for the president... to demand an investigation into a political opponent, especially a foreign power where there is, at best, dubious belief that this would be a completely impartial investigation" -- was something that "would not be tolerated in many places around the world."

"In Russia, my act of expressing concern to the chain of command in an official and private channel would have severe personal, professional repercussions and offering public testimony involving the president would surely cost me my life," Lt Col Vindman said.

Trump impeachment: Who's who in the Ukraine scandal Show all 26 1 /26 Trump impeachment: Who's who in the Ukraine scandal Trump impeachment: Who's who in the Ukraine scandal Donald Trump Accused of abusing his office by pressing the Ukrainian president in a July phone call to help dig up dirt on Joe Biden, who may be his Democratic rival in the 2020 election. He also believes that Hillary Clinton’s deleted emails - a key factor in the 2016 election - may be in Ukraine, although it is not clear why. EPA Trump impeachment: Who's who in the Ukraine scandal The Whistleblower Believed to be a CIA agent who spent time at the White House, his complaint was largely based on second and third-hand accounts from worried White House staff. Although this is not unusual for such complaints, Trump and his supporters have seized on it to imply that his information is not reliable. Expected to give evidence to Congress voluntarily and in secret. Getty Trump impeachment: Who's who in the Ukraine scandal The Second Whistleblower The lawyer for the first intelligence whistleblower is also representing a second whistleblower regarding the President's actions. Attorney Mark Zaid said that he and other lawyers on his team are now representing the second person, who is said to work in the intelligence community and has first-hand knowledge that supports claims made by the first whistleblower and has spoken to the intelligence community's inspector general. The second whistleblower has not yet filed their own complaint, but does not need to to be considered an official whistleblower. Getty Trump impeachment: Who's who in the Ukraine scandal Rudy Giuliani Former mayor of New York, whose management of the aftermath of the September 11 attacks in 2001 won him worldwide praise. As Trump’s personal attorney he has been trying to find compromising material about the president’s enemies in Ukraine in what some have termed a “shadow” foreign policy. In a series of eccentric TV appearances he has claimed that the US state department asked him to get involved. Giuliani insists that he is fighting corruption on Trump’s behalf and has called himself a “hero”. AP Trump impeachment: Who's who in the Ukraine scandal Volodymyr Zelensky The newly elected Ukrainian president - a former comic actor best known for playing a man who becomes president by accident - is seen frantically agreeing with Trump in the partial transcript of their July phone call released by the White House. With a Russian-backed insurgency in the east of his country, and the Crimea region seized by Vladimir Putin in 2014, Zelensky will have been eager to please his American counterpart, who had suspended vital military aid before their phone conversation. He says there was no pressure on him from Trump to do him the “favour” he was asked for. Zelensky appeared at an awkward press conference with Trump in New York during the United Nations general assembly, looking particularly uncomfortable when the American suggested he take part in talks with Putin. AFP/Getty Trump impeachment: Who's who in the Ukraine scandal Mike Pence The vice-president was not on the controversial July call to the Ukrainian president but did get a read-out later. However, Trump announced that Pence had had “one or two” phone conversations of a similar nature, dragging him into the crisis. Pence himself denies any knowledge of any wrongdoing and has insisted that there is no issue with Trump’s actions. It has been speculated that Trump involved Pence as an insurance policy - if both are removed from power the presidency would go to Democratic House Speaker Nancy Pelosi, something no Republican would allow. AP Trump impeachment: Who's who in the Ukraine scandal Rick Perry Trump reportedly told a meeting of Republicans that he made the controversial call to the Ukrainian president at the urging of his own energy secretary, Rick Perry, and that he didn’t even want to. The president apparently said that Perry wanted him to talk about liquefied natural gas - although there is no mention of it in the partial transcript of the phone call released by the White House. It is thought that Perry will step down from his role at the end of the year. Getty Trump impeachment: Who's who in the Ukraine scandal Joe Biden The former vice-president is one of the frontrunners to win the Democratic nomination, which would make him Trump’s opponent in the 2020 election. Trump says that Biden pressured Ukraine to sack a prosecutor who was investigating an energy company that Biden’s son Hunter was on the board of, refusing to release US aid until this was done. However, pressure to fire the prosecutor came on a wide front from western countries. It is also believed that the investigation into the company, Burisma, had long been dormant. Reuters Trump impeachment: Who's who in the Ukraine scandal Hunter Biden Joe Biden’s son has been accused of corruption by the president because of his business dealings in Ukraine and China. However, Trump has yet to produce any evidence of corruption and Biden’s lawyer insists he has done nothing wrong. AP Trump impeachment: Who's who in the Ukraine scandal William Barr The attorney-general, who proved his loyalty to Trump with his handling of the Mueller report, was mentioned in the Ukraine call as someone president Volodymyr Zelensky should talk to about following up Trump’s preoccupations with the Biden’s and the Clinton emails. Nancy Pelosi has accused Barr of being part of a “cover-up of a cover-up”. AP Trump impeachment: Who's who in the Ukraine scandal Mike Pompeo The secretary of state initially implied he knew little about the Ukraine phone call - but it later emerged that he was listening in at the time. He has since suggested that asking foreign leaders for favours is simply how international politics works. Gordon Sondland testified that Pompeo was "in the loop" and knew what was happening in Ukraine. Pompeo has been criticised for not standing up for diplomats under his command when they were publicly criticised by the president. AFP via Getty Trump impeachment: Who's who in the Ukraine scandal Nancy Pelosi The Democratic Speaker of the House had long resisted calls from within her own party to back a formal impeachment process against the president, apparently fearing a backlash from voters. On September 24, amid reports of the Ukraine call and the day before the White House released a partial transcript of it, she relented and announced an inquiry, saying: “The president must be held accountable. No one is above the law.” Getty Trump impeachment: Who's who in the Ukraine scandal Adam Schiff Democratic chairman of the House intelligence committee, one of the three committees leading the inquiry. He was criticized by Republicans for giving what he called a “parody” of the Ukraine phone call during a hearing, with Trump and others saying he had been pretending that his damning characterisation was a verbatim reading of the phone call. He has also been criticised for claiming that his committee had had no contact with the whistleblower, only for it to emerge that the intelligence agent had contacted a staff member on the committee for guidance before filing the complaint. The Washington Post awarded Schiff a “four Pinocchios” rating, its worst rating for a dishonest statement. Reuters Trump impeachment: Who's who in the Ukraine scandal Lev Parnas and Igor Fruman Florida-based businessmen and Republican donors Lev Parnas (pictured with Rudy Giuliani) and Igor Fruman were arrested on suspicion of campaign finance violations at Dulles International Airport near Washington DC on 9 October. Separately the Associated Press has reported that they were both involved in efforts to replace the management of Ukraine's gas company, Naftogaz, with new bosses who would steer lucrative contracts towards companies controlled by Trump allies. There is no suggestion of any criminal activity in these efforts. Reuters Trump impeachment: Who's who in the Ukraine scandal William Taylor The most senior US diplomat in Ukraine and the former ambassador there. As one of the first two witnesses in the public impeachment hearings, Taylor dropped an early bombshell by revealing that one of his staff – later identified as diplomat David Holmes – overheard a phone conversation in which Donald Trump could be heard asking about “investigations” the very day after asking the Ukrainian president to investigate his political enemies. Taylor expressed his concern at reported plans to withhold US aid in return for political smears against Trump’s opponents, saying: “It's one thing to try to leverage a meeting in the White House. It's another thing, I thought, to leverage security assistance -- security assistance to a country at war, dependent on both the security assistance and the demonstration of support." Getty Images Trump impeachment: Who's who in the Ukraine scandal George Kent A state department official who appeared alongside William Taylor wearing a bow tie that was later mocked by the president. He accused Rudy Giuliani, Mr Trump’s personal lawyer, of leading a “campaign of lies” against Marie Yovanovitch, who was forced out of her job as US ambassador to Ukraine for apparently standing in the way of efforts to smear Democrats. Getty Images Trump impeachment: Who's who in the Ukraine scandal Marie Yovanovitch One of the most striking witnesses to give evidence at the public hearings, the former US ambassador to Ukraine received a rare round of applause as she left the committee room after testifying. Canadian-born Yovanovitch was attacked on Twitter by Donald Trump while she was actually testifying, giving Democrats the chance to ask her to respond. She said she found the attack “very intimidating”. Trump had already threatened her in his 25 July phone call to the Ukrainian president saying: “She’s going to go through some things.” Yovanovitch said she was “shocked, appalled and devastated” by the threat and by the way she was forced out of her job without explanation. REUTERS Trump impeachment: Who's who in the Ukraine scandal Alexander Vindman A decorated Iraq War veteran and an immigrant from the former Soviet Union, Lt Col Vindman began his evidence with an eye-catching statement about the freedoms America afforded him and his family to speak truth to power without fear of punishment. One of the few witnesses to have actually listened to Trump’s 25 July call with the Ukrainian president, he said he found the conversation so inappropriate that he was compelled to report it to the White House counsel. Trump later mocked him for wearing his military uniform and insisting on being addressed by his rank. Getty Images Trump impeachment: Who's who in the Ukraine scandal Jennifer Williams A state department official acting as a Russia expert for vice-president Mike Pence, Ms Williams also listened in on the 25 July phone call. She testified that she found it “unusual” because it focused on domestic politics in terms of Trump asking a foreign leader to investigate his political opponents. Getty Images Trump impeachment: Who's who in the Ukraine scandal Kurt Volker The former special envoy to Ukraine was one of the few people giving evidence who was on the Republican witness list although what he had to say may not have been too helpful to their cause. He dismissed the idea that Joe Biden had done anything corrupt, a theory spun without evidence by the president and his allies. He said that he thought the US should be supporting Ukraine’s reforms and that the scheme to find dirt on Democrats did not serve the national interest. Getty Images Trump impeachment: Who's who in the Ukraine scandal Tim Morrison An expert on the National Security Council and another witness on the Republican list. He testified that he did not think the president had done anything illegal but admitted that he feared it would create a political storm if it became public. He said he believed the moving the record of the controversial 25 July phone call to a top security server had been an innocent mistake. Getty Images Trump impeachment: Who's who in the Ukraine scandal Gordon Sondland In explosive testimony, one of the men at the centre of the scandal got right to the point in his opening testimony: “Was there a quid pro quo? Yes,” said the US ambassador to the EU who was a prime mover in efforts in Ukraine to link the release of military aid with investigations into the president’s political opponents. He said that everyone knew what was going on, implicating vice-president Mike Pence and secretary of state Mike Pompeo. The effect of his evidence is perhaps best illustrated by the reaction of Mr Trump who went from calling Sondland a “great American” a few weeks earlier to claiming that he barely knew him. AP Trump impeachment: Who's who in the Ukraine scandal Laura Cooper A Pentagon official, Cooper said Ukrainian officials knew that US aid was being withheld before it became public knowledge in August – undermining a Republican argument that there can’t have been a quid pro quo between aid and investigations if the Ukrainians didn’t know that aid was being withheld. Getty Images Trump impeachment: Who's who in the Ukraine scandal David Hale The third most senior official at the state department. Hale testified about the treatment of Marie Yovanovitch and the smear campaign that culminated in her being recalled from her posting as US ambassador to Ukraine. He said: “I believe that she should have been able to stay at post and continue to do the outstanding work.” EPA Trump impeachment: Who's who in the Ukraine scandal Fiona Hill Arguably the most confident and self-possessed of the witnesses in the public hearings phase, the Durham-born former NSC Russia expert began by warning Republicans not to keep repeating Kremlin-backed conspiracy theories. In a distinctive northeastern English accent, Dr Hill went on to describe how she had argued with Gordon Sondland about his interference in Ukraine matters until she realised that while she and her colleagues were focused on national security, Sondland was “being involved in a domestic political errand”. She said: “I did say to him, ‘Ambassador Sondland, Gordon, this is going to blow up’. And here we are.” AP Trump impeachment: Who's who in the Ukraine scandal David Holmes The Ukraine-based diplomat described being in a restaurant in Kiev with Gordon Sondland while the latter phoned Donald Trump. Holmes said he could hear the president on the other end of the line – because his voice was so “loud and distinctive” and because Sondland had to hold the phone away from his ear – asking about the “investigations” and whether the Ukrainian president would cooperate. REUTERS

Republicans didn't like the message, so they focused their efforts on shooting the messenger.

Over the course of the four-and-a-half hour hearing, Republicans questioned Lt Col Vindman's competence, his obedience to his chain of command, his commitment to serving his country in a non-partisan manner, and even his loyalty to the country he'd called home since age 3 -- the country for which he'd shed blood in 2003, when he received a Purple Heart after being wounded by an terrorist improvised explosive device in Iraq.

But in his first -- and what he said was "hopefully [his] last" appearance before a congressional committee, Lt Col Vindman gave no quarter to his Republican inquisitors.

When Republican counsel Steve Castor pressed him on an offer he'd received from a Ukrainian official who'd raised the idea of Vindman, who was born in what is now Ukraine, becoming that country's defence minister, Vindman said he ""chain of command and the appropriate counterintelligence folks."

"I'm an American," Vindman said. "I came here when I was a toddler and I immediately dismissed these offers. Did not entertain them."

But Castor wouldn't drop the matter. He continued asking Vindman about the offer he'd rejected, even asking if the offer had come in Ukrainian or English, and if he'd left the door open to accepting the job.

"Was there a reason that he had to come back and ask a second and third time or was he just trying to convince you" Castor asked.

Vindman's reply came immediately: "Counsel, it's -- you know what? The whole notion is rather comical that I was being asked to consider whether I would want to be the minister of defense."

Later on, Representative Jim Jordan, the Ohio Republican who'd been moved onto the committee to bolster members' defense of the president, clashed with Vindman over whether his former boss, Dr Fiona Hill, had questioned his judgement or express concerns with his job performance.

But Vindman came prepared. In response, he read a copy of Dr Hill's comments to his last performance review: "Alex is top 1 per cent military officer and the best Army officer I have worked with in my 15 years of government service. He is brilliant, unflappable, and exercises excellent judgement' -- I'm sorry -- 'Was exemplary during numerous visits,' so forth and so on. I think you get the idea."

Jordan dropped that line of questioning, but later turned to pressing Vindman on why he took his concerns about Mr Trump's July 25 call to a National Security Council lawyer, rather than go to a supervisor.

"You not only didn't go to your boss... you went straight to your lawyer," Jordan said.

"I did my core function, which is coordination," Vindman replied. "I spoke to the appropriate people within the inner-agency and then circling back around, [my attorney] told me not to talk to anybody."

Jordan, unsatisfied with the lieutenant colonel's explanation, fired back.

"You talked to someone and you won't tell us who it is," Mr Jordan said, a subtle implication that Vindman was one of the National Security Council staffers who spoke to the Intelligence Community whistleblower who Republicans have been trying to unmask.

"You talked to the one guy who Adam Schiff won't tell us who it is," he continued, almost shouting when Vindman interjected:

"Representative Jordan, I did my job," he said.

As the White House's official Twitter account pushed out attacks on Vindman -- who still serves on the National Security Council and works in the White House itself -- other Republicans continued the attack.

During a break in the hearing, Rep. Scott Perry, R-Pennsylvania, criticized Vindman's decision to wear his Army dress uniform when offering testimony that was unflattering to Mr Trump, even though it is required wear for any military officer testifying before Congress.

"I think that there's been decisions made here [by Vindman to wear the uniform] and they may or may not have been appropriate. You have to be sensitive to the fact that when you testify, your testimony is a reflection of the United States military whether you intend it to be or not," Perry said.

"When you're serving in uniform, there's one commander-in-chief, and while you might question personally that commander-in-chief, your job is to take the order and move out, period," he continued.

When it was pointed out to Perry that Vindman is the White House's Ukraine expert, he attacked the decorated Army veteran further.

"He's an expert but he didn't know a whole lot of the answers to the questions about Ukraine, and yet he's the expert," he said.

Trump impeachment: Jim Jordan hints whistleblower collaborated with Democrats

North Carolina Republican Mark Meadows, an Oversight Committee member who attended the morning session, wouldn't say whether Vindman was a credible witness.

"That's a decision for the American people to make," he said.

When asked why Vindman's rejection of an offer to be Ukraine's defence minister wasn't evidence of the esteem in which he was held by the government of a close American ally, Meadows laughed and compared the offer to Vindman to the Russian government offering him a job.

"That's a ridiculous question," he said.

But current and former colleagues of Meadows and Jordan decried the attacks on Vindman's character and loyalty.

One member of the intelligence committee, Representative Joaquin Castro, called Republicans' tactics "unfortunate, to say the least."

"[The Republicans' case] is very weak, so they're going after the character of witnesses," he said.

One of Castro's former colleagues Illinois Republican Joe Walsh, called the GOP smears "shameful."

"Republicans today attacked a soldier for doing his job. They attacked a soldier for doing his duty," said Mr Walsh, who is currently challenging Mr Trump for the Republican nomination in 2020. "This is what you do when you sell your soul," he said.

Minnesota Democrat Dean Phillips told The Independent that he found Vindman's testimony and record of service to the United States to be "compelling."

"I think he's a very credible witness...and I'm disappointed by those who are trying to demean his character and service -- that saddens me more than anything," said Mr Phillips.

"Certain members of Congress are using language that would indicate concern about his loyalty to our country, and this is a man who has served in our armed services for years, was wounded in war, is here in uniform today and was selected by the White House to be their Ukraine expert," he continued.

"To indicate that his loyalties might be to Ukraine over the United States is really shameful."

General Wesley Clark, who served as NAtO's Supreme Allied Commander, Europe from 1997 to 2000, predicted that Republicans' attacks on his fellow Army veteran would backfire in the same way Democrats' attacks on another decorated officer once did.

Trump impeachment: President mocks witnesses for wearing military uniform and bow tie

"Remember how angry Republicans were that Democrats questioned Petraeus? [They] made him a hero," Gen Clark recalled.

"I believe Alexander Vindman will be elevated by the partisan attacks on his character," he predicted.