In the spring of 1988, in the middle of a bruising campaign for Congress and one day after tying the knot at a park on Lake Champlain, Bernie Sanders and his wife, Jane, boarded a flight with a small group of Vermonters for a 10-day trip to the Soviet Union. Sanders, who was then mayor of Burlington, later described the tour as “a very strange honeymoon” in his 1997 memoir, Outsider in the House. But it was more than that—it was also a very strange business trip.

The 12-person delegation, which included representatives from the city government, the Chamber of Commerce, and other civic institutions, hoped to break down “international barriers of hatred and mistrust,” Sanders explained in a letter to the editor of the Rutland Daily Herald prior to the departure. Specifically, he aimed to formalize a sister-city relationship with Yaroslavl, a city of about half a million people 160 miles north of Moscow—the latest addition to an ambitious foreign-policy portfolio that had already taken the mayor to Managua, Nicaragua, a few years earlier.

Sanders’ Soviet adventure, the subject of recent front-page stories in the Washington Post and New York Times, remains an object of fascination more than 30 years later.