Michael McFaul is director of the Freeman Spogli Institute for International Studies and a Hoover senior fellow at Stanford University and a contributing columnist to The Post. He is the author of “From Cold War to Hot Peace: An American Ambassador in Putin’s Russia.”

The polarization of American political life is worsening. Although I do research and commentary on U.S. national security issues — a topic that used to be more resistant to partisan divides than other issues — even this area is no longer always conducive to rational discourse. On social media platforms, in my email correspondence and occasionally even in my voice mail, I have become accustomed to fellow Americans calling me a “traitor,” a “criminal” and other words I don’t feel comfortable writing. Sometimes the attacks include physical threats. It’s disturbing, but it is one of the costs of engaging in policy discussions in the United States in 2019. Or so I tell myself, at least.

Yet this week, as I watched defenders of President Trump launch a series of disgusting and unfounded attacks on the character of Army Lt. Col. Alexander Vindman, I couldn’t help feeling that we have reached a new low. Ever the optimist, I want to believe that this latest case of vicious, over-the-top partisan rhetoric can serve as a useful opportunity for us to reflect on how far we have sunk, and reverse course. But it’s getting harder to sustain that faith.

On Tuesday, Vindman testified before House impeachment investigators about the Trump-Ukraine scandal. He was subpoenaed because he served (and continues to serve) as a director at the National Security Council, responsible for Ukrainian affairs, during some of the events the committee is scrutinizing. His position meant that Vindman interacted with most of the government officials who made and implemented U.S. policy toward Ukraine. He also listened in on the infamous July 25 phone call in which Trump asked Ukrainian President Volodymyr Zelensky for help in digging up (or making up) dirt on the family of his political opponent, former vice president Joe Biden.

In his written, published testimony, Vindman confirmed the basic facts of an attempt by Trump and his close associates to use public office for private gain. In his statement, Vindman never went beyond the facts; he added no opinion or political commentary. He explained why the president’s actions seemed wrong to him and why he expressed his misgivings about this scheme through the proper chain of command, as every soldier is trained to do.

Yet, even before Vindman appeared before the committees, Trump-friendly commentators were assailing his character and loyalty. Former congressman Sean Duffy asserted, “It seems very clear that he is incredibly concerned about Ukrainian defense. I don’t know that he’s concerned about American policy. . . . We all have an affinity to our homeland where we came from. . . . He has an affinity for the Ukraine.” University of California at Berkeley law professor John Yoo implied that the lieutenant colonel might be guilty of espionage for talking to Ukrainian officials, a normal part of his job.

Others suggested that Vindman might have dual loyalties because — what a scandal! — he spoke Ukrainian. Trump himself described the decorated Army officer as a “Never Trumper” — without any evidence to support his accusation.

Such smear tactics are revolting and un-American. Vindman has served our country with honor and distinction, both on and off the battlefield. He was awarded a Purple Heart after being wounded in Iraq and has earned many more medals during his more than 20 years of service in the Army. I served with him in the U.S. Embassy in Moscow, where he was everything you would want in a military attaché: smart, knowledgeable about the country, fluent in Russian and absolutely dedicated to the mission of advancing U.S. national interests.

And he is a patriot — as you would expect from someone with his outstanding résumé. I witnessed his love of country during embassy ceremonies to honor our fallen soldiers on Veterans Day. The idea that Vindman might have dual loyalties with another nation is preposterous. Vindman was born in the totalitarian Soviet Union, not “the Ukraine.” His family, which is Jewish, fled religious persecution. He is not Soviet or Ukrainian or Ukrainian American: He is simply an American. Using birthplaces or hyphenated adjectives to disparage fellow Americans is always wrong. It is especially so in the case of Lt. Col. Vindman.

One can criticize Vindman’s actions or views without smearing him because of his ethnicity or guessing about his politics. People who devote their lives to defending our country — whether on the battlefield in Iraq or the National Security Council at the White House — take their oaths to the United States of America, not to Republicans, Democrats or individual presidents. When we are attacked again, and we will be attacked again, our enemies will not discriminate between pro-Trumpers and Never Trumpers.

Thinking she was attacking the messenger, Fox News television host Laura Ingraham accurately noted that Vindman was acting “apparently against the president’s interest.” This is true. Why? Because Vindman pledged to advance U.S. national interests, not the personal interests of the president. Usually, those interests coincide. Tragically, in this attempted quid pro quo with Ukraine, they did not. Vindman recognized the difference — and he chose to defend the interests of the United States. For this he should not be disparaged or smeared. He should be celebrated as an American hero.

Michael McFaul is director of the Freeman Spogli Institute for International Studies and a Hoover senior fellow at Stanford University and a contributing columnist to The Post. He is the author of “From Cold War to Hot Peace: An American Ambassador in Putin’s Russia.”

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