Army Lt. Col. Alexander Vindman is a decorated and wounded veteran of the Iraq War. He is no coward, and yet his hands were shaking and he was visibly nervous as he read his opening statement on Tuesday before the House Intelligence Committee. This was a reminder of what a signal act of bravery it takes for a military officer — or a Foreign Service officer or an intelligence officer — to publicly reveal that the most powerful man in the world has committed impeachable and even criminal conduct.

Vindman and his colleagues have already faced attacks that he rightly described as “vile” and “reprehensible.” After Vindman gave a deposition behind closed doors last month, President Trump denounced him as a “Never Trumper.” When asked what evidence he has of the political leanings of this career military officer who still works in the Trump White House, the president promised in his thuggish way that “We’ll be showing that to you real soon, okay?” (No such evidence has been forthcoming.) The White House Twitter account attacked Vindman, questioning his judgment, as he was testifying. So did Donald Trump Jr. — incessantly.

Sen. Ron Johnson (R-Wis.) stepped in Monday to supply speculation that Vindman “fits” the “profile” of anti-Trump bureaucrats who “try to sabotage his policies and, if possible, remove him from office.” His evidence? That Vindman told him in May “that it was the position of the NSC that our relationship with Ukraine should be kept separate from our geopolitical competition with Russia.” Johnson was rightly skeptical that this would be possible, but this is hardly evidence of anti-Trump animus. Presumably Vindman suggested keeping Ukraine separate from relations with Russia because Trump has an inexplicable soft spot for Russia.

The president has been even more scathing in denouncing Vindman’s fellow witnesses, Marie Yovanovitch and Jennifer Williams: He absurdly accused Yovanovitch of being responsible for the dire state of Somalia and Ukraine — and just as absurdly accused Williams, who works for Vice President Pence, of being a “Never Trumper.” Sounding more like a mob boss than a democratically elected leader, Trump has threatened that Yovanovitch will “go through some things.” She already has, having been fired from her post as ambassador in Ukraine. House Republicans are now desperate to out the whistleblower so they can put this truth-teller through the wringer, too, even though the complaint has been entirely vindicated.

But for pure maliciousness, it is hard to top the gall of Trump partisans who question Vindman’s loyalty to the United States because he emigrated here as a toddler from the Soviet Union. Republican counsel Steve Castor continued those nasty aspersions of dual loyalty on Tuesday by extensively questioning Vindman about an offer extended to him out of the blue by a Ukrainian official to become defense minister of Ukraine. Vindman said he rejected the proposal and reported it to his superiors, because he is an American. Questioning Vindman about this — and demanding to know whether he had been speaking Ukrainian — is sheer McCarthyism.

These vicious attacks raise a real danger to Vindman — and not just the danger of having his good name smeared. The Wall Street Journal reported on Tuesday that “the U.S. Army is prepared to move Col. Vindman and his family onto a military base to ensure their security if it is determined that they are in physical danger.” That a war hero might be in physical danger marks a new low in Republican attempts to defame and intimidate the witnesses against the president.

Vindman ended his opening statement with a stirring plea that had some spectators wiping away tears: “Dad, my sitting here today, in the U.S. Capitol talking to our elected officials is proof that you made the right decision 40 years ago to leave the Soviet Union and come here to United States of America in search of a better life for our family. Do not worry. I will be fine for telling the truth.”

Vindman’s reassurance to his father resonated with me — another Jewish immigrant from the Soviet Union who came to the United States as a young boy in the 1970s. People raised in tyrannical regimes such as the Soviet Union grow up with a terror of doing anything that could result in a trip to the gulag. As Vindman said, “In Russia, my act of … offering public testimony involving the president would surely cost me my life.” That paralyzing fear is hard to shake even when you move to a free country. Even today, my 84-year-old, Russian-born stepfather, who has been living in Los Angeles for more than four decades, expresses concern that something terrible might happen to me because of my outspoken criticism of the president.

Like Vindman, I assure my loved one that I will be fine — and I truly believe this because I am exercising my constitutionally protected free-speech rights. But then I am not an existential threat to Trump’s political survival; Vindman is. Along with his fellow witnesses, he is presenting incontrovertible evidence that the president has committed high crimes and misdemeanors. No wonder Vindman is visibly nervous. In testifying anyway, he is vindicating the highest ideals of a country where no man, not even the president, is above the law. Vindman was not born here, but he is a far better American than the Trump toadies who question his loyalty.

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