These positions are actually quite consistent with the politics of the kibbutz Sanders chose for his time in Israel. Daniel Greenfield of Front Page Magazine has the story:

It is sometimes maintained that Bernie Sanders can’t be as anti-Israel as some of his positions would indicate, because he spent time on a kibbutz there. After all, this is a guy who in the January 17 Democrats’ presidential debate said, ““I think what we’ve got to do is move as aggressively as we can to normalize relations with Iran,” and who wanted to deny weapons to Israel prior to the Yom Kippur War in the 1970s.

In 1963, Sanders had told Yossi Melman that he had been at Kibbutz Sha'ar Ha'amakim as a guest of the Hashomer Hatzair youth movement. Israel had all sorts of Kibbutzim affiliated with various political movements. Hashomer Hatzair was about as bad as it got. Kibbutz Sha'ar Ha'amakim had been co-founded by Aharon Cohen, the Arabist, who was a regular critic of Israel and opponent of its policy. He was arrested for spying for the USSR in the 50s. (snip) Other left-wing groups described them as Leninist and even Stalinist. (snip) As late as 1969, well after Bernie's 1963 visit, Dissent was describing Hashomer Hatzair kibbutzim as "Stalinist". Western lefties with a Hashomer Hatzair background include Noam Chomsky. Chomsky wrote that he was fairly close to "Hashomer Hatzair, but couldn't join because it was split between Stalinists and Trotskyites."

Kibbutz Sha'ar Ha'amakim was, in fact, part of the communist organizational support system, dedicated to the triumph of communism under the leadership of the Soviet Union.

Its founder, Ya'akov Hazan, described the USSR as a second homeland and eulogized Stalin, writing how shocked he and his comrades were, "to hear of the terrible tragedy that has befallen the nations of the Soviet Union, the world proletariat and all of progressive mankind, upon the death of the great leader and extolled commander, Josef Vissarionovich Stalin. We lower our flag in grief in memory of the great revolutionary fighter, architect of socialist construction, and leader of the world's peace movement. His huge historical achievements will guide generations in their march towards the reign of socialism and communism the world over." Al Hamishmar, the movement's paper, had a headline which read, "The Progressive World Mourns the Death of J.V. Stalin"

This sojourn in Israeli communist kibbutz is fully consistent with Sanders’s honeymoon visit to the Soviet Union (where, Rand Paul quipped, he stayed), his visit to Nicaragua’s Sandinista revolutionary leader Daniel Ortega as the first U.S. elected official when he became the mayor of Burlington, and his 1980s visit to Cuba where he met with the mayor of Havana.

So far as I know, Bernie Sanders has never repudiated his Stalinist inclinations.

Hat tip: Clarice Feldman

Photo of younger Sanders via Special Collections, University of Vermont Libraries