October 23, 2020 6:49 PM EDT

At the presidential debate on Thursday, as the candidates were talking about their visions for the future, one comment about the past caught a lot of viewers’ attention.

After President Trump said that it was a good thing that he had a good relationship with North Korean dictator Kim Jong Un, as Presidents are supposed to maintain good relationships with other world leaders, Democratic candidate Joe Biden fired back: “We had a good relationship with Hitler before he, in fact, invaded Europe, the rest of Europe. Come on.”

Some pundits shared that one-line comparison without any additional context, while others pointed to the trope known as “Godwin’s Law“: the idea that, allowed to go on long enough, any online debate will eventually end in a comparison being made to Adolf Hitler or Nazism. Other Twitter users, however, concentrated on whether the analogy was historically accurate.

So is Biden right that America had a good relationship with Hitler prior to the beginning of World War II? Yes and no.

“The relationship between the U.S. and Germany in the 1930s is very complicated and multilayered and can’t be reduced to a sound bite,” says Michael D. Hattem, Associate Director of the Yale-New Haven Teachers Institute and an expert on how early American politics are remembered throughout U.S. history. “While the Congress was committed to non-interventionism, the financial and corporate sector had lots of interests in Germany. A bunch of American companies like IBM [and] Coca Cola had large investments in Germany in the 1930s, and a number of them invested more heavily in Germany after Hitler came to power.”

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At the heart of the matter is what one means by “America.” The American government did not have some kind of special, formalized relationship with Nazi dictator Adolf Hitler in the years following his rise to power, given a strong preference in Congress and in the White House to stay out out of European affairs after World War I. Some American businesses wanted to do business in Nazi Germany and some individual Americans did have a good impression of Hitler and felt as if he shared their values. These American Nazi groups went underground after Pearl Harbor, only to re-emerge after the war—and some are still thriving today.

“I think Biden was being sarcastic when he said we had a great relationship with Hitler before he invaded the rest of Europe. We didn’t have a great relationship with Hitler but there were many Hitler supporters in the U.S.,” says Steve Ross, professor of History at the University of Southern California and author of Hitler in Los Angeles: How Jews Foiled Nazi Plots Against Hollywood and America. “The America First movement was very much a pro-Nazi movement, and it was those people who said we should have a great relationship with Hitler. A contingent wanted America to remain neutral only so long as Hitler was able to rearm Germany, conquer Europe and then they wanted Hitler to conquer America or be part of an alliance with Germany.”

America First was a powerful movement that boasted a lot of influential supporters (including Walt Disney, Frank Lloyd Wright, John F. Kennedy and Gerald Ford) who weren’t necessarily pro-Nazi but were against American involvement in European affairs, a feeling prompted by the idea that the U.S. effort in World War I proved futile. The America First movement was particularly active in areas of the U.S. with large German American populations.

In addition, some Americans were drawn to Hitler’s ideas—not just his outspokenness against communism, but also his anti-Semitism and racism. The economic turmoil of the 1930s also fueled Nazi sympathizers, Ross says, as people in the U.S. looked for scapegoats to blame for the Great Depression.

American support for those abhorrent ideas was not mere talk. After Kristallnacht in November 1938, Ross says, American Nazis began preparing for a future in which they would take a key role in American politics. “Nazis in America started setting up cells and the cells were planning for the day when, what they said is, the communists would rise up to overthrow the American government,” Ross says. “When they did, the Nazi, pro-Hitler forces would rise up, defeat communism, and take over the American government. That’s what was going on in our country, but that past is largely untold because it’s an unpleasant part of American history.”

At the time, though, that thread in American life was hardly hidden. On Feb. 20, 1939, more than 20,000 people flocked to a German American Bund pro-Nazi rally at Madison Square Garden. The group displayed a massive image of George Washington in an attempt to show that “American Nazism was American,” says Hattem. “The American Nazis used aspects of the American Revolution and American history to achieve a more mainstream appeal” and to link America First’s non-interventionist outlook to Washington’s 1796 warning against getting involved in European wars.

And, just as some Americans admired some of Hitler’s views, the Nazi dictator also admired the way America did things, looking to its eugenics movement and caste system as he designed his own.

While Pearl Harbor effectively put an end to support for non-intervention on Dec. 7, 1941, that didn’t mean the American pro-Nazi groups went away. They just went underground, according to Ross. While many American troops came back from World War II with a new respect for tolerance, there were also many who expected the U.S. “to be the same as it was before the war—and that meant for them that Blacks, Jews [and] people of color knew their place, and that their place was always below white Christian America. A white supremacist movement comes out of World War II that persists until this day,” he says, “and that is not talked about.”

Today, however, the influence of white supremacist movements in American life is once again on the rise. To historians, that fact is part of a story that dates back decades, and that can offer crucial context to what’s happening in 2020.

“So Hitler did have supporters in this country,” Ross says, “and they supported him after the war.”

Write to Olivia B. Waxman at olivia.waxman@time.com.

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