evidence: The Soviet sojourn has long been an extraordinary, if little understood, chapter in Sanders lore. He has for years used it to help explain his views about foreign policy, citing it as recently as last month. The trip garnered brief mention in the 2016 presidential campaign, but earlier this year, a video from a Vermont community television station was posted online that showed a few minutes of Sanders’s unlikely celebration with the Soviets. Right-leaning websites suggested Sanders was cozying up to communists, underscoring how the trip might be used against the senator if he becomes the Democratic nominee. [...] The trip to the Soviet Union was, at that time, Sanders’s most significant foreign venture. U.S. relations with the Soviet Union were in the midst of transformation. Just before Sanders departed, Reagan traveled to Moscow for a summit with Soviet leader Mikhail Gorbachev, who was pushing for openness and reform. As a result, Sanders muted his criticism of Reagan, praising the summit as "a major step forward for humanity. . . . What we are doing is actually the same thing at a lower level."