Donald Trump has dismissed concern about undue Russian influence on his campaign and presidency as “fake news”—a fiction created by Democrats to explain away their defeat. Much of the news isn’t fake; it includes, among other things, a very real U.S. intelligence assessment that the Russian government interfered in the 2016 election in part to help Trump, and the very real dismissal of Trump’s campaign chairman and national-security adviser amid scrutiny of their connections to the Kremlin. But Trump is right that the issue has become partisan, scrambling American politics. The Democrats have largely replaced the Republicans as antagonists of Russia and champions of the U.S. intelligence community.

“It is now the Republican Party, which at the height of the Cold War tarred its liberal opponents as Kremlin cronies, that must defend its president from charges of dual loyalty,” Joshua Zeitz recently observed in Politico. Noah Millman of The American Conservative has gone further, arguing that Trump’s opponents, in using “increasingly extreme and irresponsible rhetoric” to suggest that there’s a “Manchurian Candidate” in the White House, are perpetrating a “new Red Scare.”

As speculation swirled about the ties between Trump aides and Russian officials, and Russian infiltration of the U.S. political system more broadly, I spoke with several historians of the last Red Scare—that period from the late 1940s through the 1950s made infamous by Senator Joseph McCarthy’s ruthless and mostly baseless campaign to stop communists and Soviet spies from subverting American government and society. The scholars generally agreed on three lessons that could be applied to the present moment.

Keep the Current Threat in Perspective

During World War II, when the Soviet Union and United States were allies, Soviet intelligence “thoroughly infiltrated the American government,” even the project to build the atomic bomb, according to Harvey Klehr, a historian at Emory University. Among the hundred-plus Soviet spies in the federal government were Harry Dexter White, a high-ranking official at the Treasury Department, Duncan Lee, a top aide at the predecessor to the Central Intelligence Agency, and Laurence Duggan, the head of the Latin America desk at the State Department. The nature of this infiltration didn’t become public until the late 1940s, when former Soviet spies like Whittaker Chambers and Elizabeth Bentley began testifying before the House Un-American Activities Committee, at which point it “became the issue in American political life,” paving the way for McCarthy’s witch hunt in the early ’50s, Klehr said.

At the time, noted John Earl Haynes, a retired Library of Congress historian who has collaborated with Klehr, Soviet-style communism posed a genuine ideological threat to the American way of life. There was a robust U.S. Communist Party. Many Americans were sympathetic to the Soviet Union as a model of what they wanted the United States to become. “There’s nothing like that today,” Haynes said. “There is no pro-Putin party [in America]. … There’s no large group of people who really want the United States to become a clone of Putin’s Russia.” The Soviet Union also had a “universalistic ambition to make the whole world communist,” including the U.S., whereas Vladimir Putin seems more intent on “opportunistic meddling.” (Richard Fried, a professor emeritus at the University of Illinois at Chicago, did point out that some Trump supporters are enamored with Putin’s reactionary nationalism.)

On the other hand, Haynes added, Russian intelligence agencies today appear more interested in manipulating U.S. policy and public opinion than the Soviet intelligence agencies of the ’30s, ’40s, and ’50s, which focused more on information-gathering.

During the Red Scare period, Haynes said, there was “a basis for fears of communist subversion” since there had been “real spies in the government,” though most had been purged by the late 1940s and McCarthy was “95 percent wrong” about the people he accused.

“Yes, there was a problem with infiltration,” said Fried. But “by 1950, it had been pretty well taken care of. McCarthy comes along very late in the day. If there is a problem today [with Trump’s links to Russia], I don’t think it can be said that it’s been taken care of.”

Release as Much Information as Possible

In the 1940s, the U.S. Army’s Signal Intelligence Service, the precursor to the National Security Agency, began decrypting Soviet cables that revealed the identities of spies in the U.S. government, in what was known as the Venona project. But for a variety of reasons—including concern that the evidence wouldn’t be admissible in U.S. courts and a desire to keep the Soviets in the dark about the decryptions—U.S. intelligence officials never disclosed the project’s findings to the public. Only in 1995, after the collapse of the Soviet Union, were the materials released.

Klehr wonders whether the Venona messages should have been revealed in the ’40s and ’50s. “Quite often the facts get lost in the hysteria,” he said, and sharing the intelligence with the American people would have introduced more facts into the debate about communist subversion. Doing so would have also “demonstrated that American intelligence had—a little late, but eventually—gotten this information,” he added. “One of McCarthy’s major weapons was this argument that the Roosevelt and Truman administrations,” which had been slow to respond to Soviet infiltration of the U.S. government, “had covered all this up.”

Will U.S. intelligence agencies—members of which have so far leaked through unofficial channels only vague information about Trump aides’ connections with the Russian government—formally release transcripts of Michael Flynn’s communications with the Russian ambassador? Klehr asked. Those agencies might reasonably conclude, as U.S. intelligence agencies did in the 1940s, that public disclosure of such materials would put their ability to do their work at risk.

During the Red Scare period, the American public “didn’t have the benefit of knowing exactly what was true and exactly what wasn’t true,” Haynes said, in reference to the Venona decryptions. “And when there’s doubt, that is the atmosphere which allows irresponsible partisanship to grow.” Things left ambiguous are liable to be exaggerated, he argued.

Fried agreed with Klehr and Haynes about the merits of releasing the Venona cables. It’s “an argument for clarity and openness,” he said. But he noted that it’s unclear whether President Truman even knew about the project at the time and could have ordered the release of the intelligence.

Ellen Schrecker, a professor emeritus at Yeshiva University, disagreed. By showing how much Soviet spying had been going on, she argued, the Venona documents might have only “reinforced” the hysteria.

Remember That Fear of Russia Will Be Politicized

In the hands of Joe McCarthy, a Republican, a “well-placed fear” of communist subversion was “used as a partisan club to bash away at” the Democrats and specifically the Truman administration, Haynes said. Most famously, McCarthy accused two of Harry Truman’s secretaries of state, George Marshall and Dean Acheson, of orchestrating “a conspiracy on a scale so immense as to dwarf any previous venture in the history of man”—an allegation that was absolutely false.

Partisanship also played a role in why the Truman administration didn’t publicize its crackdown on Soviet spies during the early Cold War; it didn’t want to risk the political fallout from acknowledging that it hadn’t prevented the Soviets from penetrating the U.S. government in the first place. Truman, Haynes noted, was “in the odd position of saying: ‘What the Republicans are [saying] happened didn’t happen, but it’s not going to happen again.’”

“Under the pressure of partisanship,” Haynes observed, “all kinds of people will do and say things which are really rather silly and exaggerated.”

McCarthyism “was essentially, in its most blatant form, an attempt to repress political dissent in one form or another,” Schrecker argued. And the key to understanding this politicization of a threat is that it was exaggeration rooted partly in reality. “That was the thing about McCarthyism: One of the reasons why it was so pervasive was that it was plausible,” she said.  

Today, the “Democratic Party establishment is trying to ride the [Russia] issue as best they can,” though so far “they don’t have particularly strong evidence,” Schrecker added. (The concern about Trump’s Russia ties is not wholly partisan; a number of Republican lawmakers and conservative commentators have expressed alarm as well.) People should repeatedly ask why “the Democrats in particular, but [also] a number of other establishment politicians, including some Republicans, are hyping this” threat, she advised. Is it because the facts support it? Or “is it that we need to have an enemy?”