Here is a picture of Gorbachev with Steve. Here is another picture of Gorbachev with Steve, this one with some Russian dissidents. And look, there is one of Gorbachev and Katrina, Steve’s wife, holding their infant daughter. There is even a Gorbachev magnet on the refrigerator.

Walking around this book-lined apartment on Manhattan’s Upper West Side on an August evening, it is almost as though the man with the world’s most famous birthmark is the third partner in the marriage of Stephen F. Cohen and The Nation editor-publisher Katrina vanden Heuvel.

For more than four decades, Cohen has been a leading voice on Russian affairs, pinballing between the academy, where he is now emeritus at Princeton University and NYU, and the media, influencing world events along the way. Few scholarly works can be said to have equaled the direct political impact of Cohen’s 1973 biography of the Soviet founding father Nikolai Bukharin. Bukharin and the Bolshevik Revolution (Alfred A. Knopf) didn’t just suggest a new understanding of the Russian Revolution when it was released in the middle of the Cold War — it profoundly affected the course of that war. Mikhail Gorbachev’s chief foreign-policy adviser, Anatoly Chernyaev wrote, "Some of us had already read the book, and we encouraged Gorbachev to do so. He took the book on vacation with him. He read it closely and kept quoting it to me. … The re-evaluation of Bukharin’s role and personality opened the sluice gates to reconsidering our whole ideology."

Gorbachev’s affection for Cohen’s ideas — and for Cohen himself — turned a lowly scholar of the Russian Revolution into an intellectual VIP who sat in meetings with heads of state. Eric Alterman, a journalism professor at Brooklyn College and a Nation columnist who has known Cohen for decades, calls Bukharin and the Bolshevik Revolution "one of the most consequential books of the past century." It realized "the dream of all writers to have an effect not only on world leaders but also on history itself."

But these days, Cohen is better known for his views on a different Russian leader. In his columns and media appearances in recent years, he has become perhaps the most prominent defender of Vladimir Putin. "Putin is not a thug," he declared on CNN. "He’s not a neo-Soviet imperialist who’s trying to recreate the Soviet Union. He’s not even anti-American." The defense extends to the U.S. president, who has had some nice things to say about Putin. "The number-one threat to the United States today," Cohen told Fox News, is the continuing investigation of Trump’s ties to Russia: "There is no evidence there was any wrongdoing."...