Independent Senator Bernie Sanders criticized the U.S. for its foreign policy during a visit to the Soviet Union in 1988.

A Washington Post analysis of the video, which was unearthed earlier this year, reveals new information about the details of the then-Vermont mayor's dinner with Soviets.

During a banquet attended by about 100 people, the then 46-year-old mayor of Burlington, VT, blasted U.S. intervention in other countries, according to interviews with five individuals who accompanied Sanders on the trip.

He was newly-married to his wife Jane O'Meara and leading a delegation from his Vermont city trying to build links with the Soviets. Among the group were Ben Cohen, the local co-founder of Ben & Jerry's Ice Cream.

During the trip, which included Res Square in Moscow, Leningrad - the Soviet name for St Petersburg - and the run-down Volga city of Yaroslavl - he also criticized the cost of housing and health care in American, while praising the Soviet Union for their lower prices.

'I got really upset and walked out,' David Kelley, who had helped arrange the trip and was the only Republican in Sanders's entourage, said of the now-Democratic candidates comments.

A Washington Post examination of recently unearthed video of Bernie Sanders's trip to the Soviet Union reveals that he criticized the U.S. during his trip to the socialist state in 1988

Sanders, who was the 46-year-old mayor of Burlington, Vermont at the time of the trip, criticized the U.S. for its foreign interventions, and also blasted the cost of housing and healthcare in America

In the video, where Sanders is sitting shirtless at a table with Soviets, he can be seen and heard singing along with the others to 'This Land is Your Land'

'When you are a critic of your country, you can say anything you want on home soil,' Kelley told the Post. 'At that point, the Cold War wasn't over, the arms race wasn't over, and I just wasn't comfortable with it.'

Sanders, who is the oldest Democrat running for president at 77-years-old, humorously referred to the trip as a 'very strange honeymoon' in his book 'Outsider in the White House' since he traveled there shortly after he married his second wife, Jane, in 1988.

He traveled to the Soviet Union with Jane and about 10 others.

In the video, a shirtless Sanders can be seen sitting at a table with several Soviets and singing the Woody Guthrie song 'This Land Is Your Land.'

Previously, little other information about the trip was available, except for the accounts given by Sanders.

Sanders's senior adviser Jeff Weaver said the video was proof that the Democratic socialist candidate likes to form partnerships between groups and people who may seem at odds with each other.

Sanders described the trip to the U.S.S.R. as a 'very strange honeymoon' in his book 'Outsider in the White House' since he traveled there shortly after marrying his second wife, Jane

Reagan traveled to Moscow for a summit with Soviet leader Mikhail Gorbachev, right before Sanders' trip to the Soviet Union

'Just like his politics in the U.S. are animated by bringing ordinary people together,' Weaver said. '[The trop] was an example of that, if you can get people from everyday walks of life together, you can break through some of the animosity that exists on a governmental level.'

Mendoza Ferrer, a Sanders critic, discovered the video from a Vermont community television station archive, and a pro-Beto O'Rourke group circulated it on social media in January.

One of the leaders of the group, which was urging O'Rourke to run for president before his official bid, posted the video on his Twitter.

Sanders was mayor of Burlington, Vermont for seven years at the time of the trip, and was already vocal about foreign policy. He was often supportive of socialist and communist countries and regimes.

He wrote, 'I saw no magic line separating local, state, national and international issues… How could issues of war and peace not be a local issue?'

In 1985 he visited Nicaragua and lauded Daniel Ortega's revolution, which the U.S. president at the time, Ronald Reagan, opposed.

'I was impressed,' Sanders said at the time of Ortega's revolution in the Central American country, and also voiced admiration for the Cuban revolution led by Fidel Castro, whom many in both parties routinely denounced.

In the video, a shirtless Sanders can be seen and heard singing 'This Land is Your Land' with the rest of those at the table

Sanders is one of the candidates running in the crowded Democratic primary field for the party's bid in 2020. This is his second consecutive primary run, and he is the oldest candidate so far. Pictured Sanders arrived at a campaign rally with his wife, Jane, in Los Angeles on March 23

Howard Seaver, an official with a Burlington business group, said those on the trip saw the downside to how the Soviet Union was being run at the time.

'I think [Sanders] saw and we all saw the downside of the Soviet system,' Seaver told the Post. 'Yes, they may have had low-cost apartments, but things were very out of whack, there were food shortages, no political freedom.'

'I suspect that what Bernie saw in Russia probably affected his views that you see today, where he is not anti-free-enterprise or capitalism but he wants to have a safety net and give a fair shake to all, but certainly not to have a command economy we saw in the Soviet Union,' Seaver said.

Weaver said the main reason for Sanders's trip to the U.S.S.R. was to establish a 'sister city' with Burlington in Yaroslavl, a Russian city of about 600,000.

Right before Sanders's trip to the Soviet Union, Reagan traveled to Moscow for a summit with Soviet leader Mikhail Gorbachev, who the U.S. president eventually called to tear down the wall separating east and west Berlin.