People walk in Red Square, with St. Basil’s Cathedral seen in the background, in central Moscow. (Maxim Zmeyev/Reuters)

The CIA has concluded with “high confidence” that Russia intervened covertly during the presidential election to promote Donald Trump’s candidacy. They based this assessment on the discovery that Russian security agencies had hacked the Republican National Committee, the Democratic National Committee and the Hillary Clinton campaign — and had released selected Democratic documents to WikiLeaks to undermine Clinton’s candidacy.

If true, Russia’s actions are reminiscent of Cold War covert political warfare, with an Internet-era twist. Here are six key things my research uncovered about those efforts.

What do we know about covert political warfare?

Obviously, studying covert interventions is tough. By definition, the operations are designed so that the intervening state can plausibly deny it was involved, deflecting blame onto other actors. It’s impossible to get reliable cross-national data, given how widely countries vary in their rules about government transparency and freedom of the press. Add in flourishing conspiracy theories, and it can be hard to separate historical fact from fiction.

To tackle these problems, I have spent the past several years investigating allegations of U.S.-backed covert regime changes during the Cold War. I’ve done so by going through relevant documents from the National Archives, National Security Archive and presidential libraries. Fortunately, the combination of the U.S. government’s declassification rules, congressional inquiries and journalistic coverage has revealed a great deal about these operations.

1. Between 1947 and 1989, the United States tried to change other nations’ governments 72 times

That’s a remarkable number. It includes 66 covert operations and six overt ones.

Of course, that doesn’t excuse Russia’s meddling in the 2016 U.S. presidential election. These 72 U.S. operations were during the Cold War — meaning that, in most cases, the Soviet Union was covertly supporting anti-U.S. forces on the other side. However, a look at these U.S. actions allows us to survey the covert activities of a major power, so we can glean insight into such interventions’ causes and consequences.

2. Most covert efforts to replace another country’s government failed

During the Cold War, for instance, 26 of the United States’ covert operations successfully brought a U.S.-backed government to power; the remaining 40 failed.

Success depended in large part on the choice of covert tactics. Not a single U.S.-backed assassination plot during this time actually killed their intended target, although two foreign leaders — South Vietnam’s Ngo Dinh Diem and the Dominican Republic’s Rafael Trujillo — were killed by foreign intermediaries without Washington’s blessing during U.S.-backed coups.

Similarly, covert actions to support militant groups trying to topple a foreign regime nearly always failed. Of 36 attempts, only five overthrew their targets. Sponsoring coups was more successful: nine out of 14 attempted coups put the U.S.-backed leaders in power.

3. Meddling in foreign elections is the most successful covert tactic (as Russia may not be surprised to learn).

I found 16 cases in which Washington sought to influence foreign elections by covertly funding, advising and spreading propaganda for its preferred candidates, often doing so beyond a single election cycle. Of these, the U.S.-backed parties won their elections 75 percent of the time.

Of course, it is impossible to say whether the U.S.-supported candidates would have won their elections without the covert assistance; many were leading in the polls before the U.S. intervention. However, as the CIA’s head of the Directorate of Intelligence, Ray S. Cline once put it, the key to a successful covert regime change is “supplying just the right bit of marginal assistance in the right way at the right time.”

In an election where Clinton won the popular vote by 2.86 million but lost the electoral college, thanks to 77,744 voters in Wisconsin, Michigan and Pennsylvania, did Russia’s covert campaign give “just the right bit of marginal assistance,” thus tipping the scales to Trump by suppressing Democratic turnout?

It’s impossible to say for sure, but the numbers were certainly close. If Clinton had replicated Obama’s 2012 turnout in those three swing states, she would have won them by more than half a million votes. Even if she had been able to convert just 1 percent of these states’ Trump voters, she would have won by a combined 55,000 votes. The Clinton campaign undoubtedly had many strikes against it: high unfavorability ratings, inaccurate polling, FBI Director James B. Comey’s letter and strategic mishaps. Still, Russia’s covert campaign probably compounded these problems. Thanks to WikiLeaks’s slow trickle of hacked emails, the news cycle throughout October was flooded with embarrassing anti-Clinton stories, preventing her from building momentum after the debates.

4. Regime changes rarely work out as the intervening states expect.

A Trump presidency might not be as much of a boon for Russia as hoped or feared. Clinton warned in the third presidential debate that Putin “would rather have a puppet as president of the United States.”

However, as I show in a recent International Security article with Alexander Downes, leaders installed via regime change generally don’t act as puppets for long. Once in power, the new leaders find that acting at their foreign backers’ behest brings significant domestic opposition. They therefore tend to moderate their policies or turn against the foreign backer completely. In fact, there are already reports that the Kremlin is feeling “buyer’s remorse” over Trump’s victory, given his unpredictability.

5. Covert regime change can devastate the target countries

My research found that after a nation’s government was toppled, it was less democratic and more likely to suffer civil war, domestic instability and mass killing. At the very least, citizens lost faith in their governments.

Even if Russia didn’t make the difference in electing Trump, it successfully undermined confidence in U.S. political institutions and news media.

As historian Timothy Snyder pointed out in September, “If democratic procedures start to seem shambolic, then democratic ideas will seem questionable as well. And so America would become more like Russia, which is the general idea. If Mr. Trump wins, Russia wins. But if Mr. Trump loses and people doubt the outcome, Russia also wins.”

6. The best antidote to subterfuge is transparency.

States intervene covertly so that they don’t have to be held accountable for their actions. Amid reports that Russian hackers have been emboldened by the success of the DNC hack, exposing Moscow’s hand is the first step toward deterring future attacks against the United States and upcoming elections in Germany, France and the Netherlands. It may also be the best way to dispel disinformation and restore faith in U.S. democratic institutions at a time when 55 percent of Americans say they are troubled by Russian interference into the election,

The United States is beginning this effort. Congress has announced bipartisan investigations and Obama ordered a comprehensive report on covert foreign interference into U.S. presidential elections going back to the 2008 election.

Given how serious these allegations are, and especially considering that President-elect Trump rejects the intelligence community’s consensus conclusion, releasing these reports publicly before the inauguration could help set U.S. democracy right.

Lindsey A. O’Rourke is an assistant professor of international politics at Boston College.